Guidelines for Energy Checks and Energy Analysis in · PDF fileGuidelines for Energy Checks and Energy Analysis in Water and Wastewater Utilities November 2014. ... thermal efficiency

Guidelines for Energy Checks and Energy Analysis in Water and Wastewater Utilities

November 2014. Draft 2

Prepared for the ACWUA Task Force: Energy Efficiency, for application by members of the Arab Countries Water Utilities Association (ACWUA)

GIZ Program: ACWUA WANT - Strengthening the MENA Water Sector through Regional Networking and Training

Page 2


November 2014, Draft 2

GIZ Program: ACWUA WANT - Strengthening the MENA Water Sector through Regional Networking and Training

Main authors:

Eric Gramlich, M.Sc. Prof. Dr.-Ing. Markus Schröder Tuttahs & Meyer Ingenieurgesellschaft, Germany Members of DWA and German Water Partnership (GWP)

Project manager of the GIZ:

Dr. Thomas Petermann, ACWUA WANT GIZ Eschborn, Regional Department 3300

ACWUA Task Force: Energy Efficiency

Chairperson: Eng. Abdellatif Biad, ONEE, Morocco

ACWUA Guidelines for Energy Checks and Energy Analysis in Water and Wastewater Utilities

Page 2

Preface We are pleased to present the revised 2nd draft of the new ACWUA Guidelines on Energy Checks and Energy Analysis. They aim to guide water and wastewater utilities in the MENA region to conduct systematic and comprehensive checks and analysis of the situation in their companies in order to optimize energy use and to enhance energy efficiency while reducing energy consumption, and finally to explore options to produce energy from renewable re-sources. However, the attempts for the energy optimisation may not run counter to the ulti-mate goals of the wastewater treatment and the water pollution control.

The editors are members of the German Association for Water, Wastewater and Waste (DWA) and members of the DWA energy coordination group. By using energy guidelines of German water associations and other reference material from Germany or international sources, they ensured that the state-of-knowledge was applied. The Guidelines underwent two cycles of peer reviews, a 1st round in April and June 2014 with members of the ACWUA Task Force Energy Efficiency, and a 2nd round in September 2014 with 15 experts from Ger-many. We are very grateful to all who contributed to the reviews and to the editors to take up the recommendations to finalize the 2nd draft in November 2014.

However, this 2nd draft of the Guidelines is not the end of the process. Currently, the ACWUA WANT program is supporting two members of ACWUA, SONEDE in Tunisia and ONEE in Morocco to apply the Guidelines and conduct energy checks and energy analysis in two pilot water supply units/facilities. This process is guided and supported by German experts from HamburgWasser, one o f the biggest water and wastewater companies in Germany with a long experience in energy management. HamburgWasser is committed to the strategic target to be independent from external energy inputs latest by the year 2020.

Standards (such as ISO 50001) and Guidelines (Rules, Requirements) are typically generic - by providing a framework and common methodology for action; they are rarely aligned with actual operating procedures and workflows. It is expected that the results of the two pilot pro-jects will be used to amend and enr ich the existing 2nd draft of the Guidelines in terms of practical applications, approved performance indicators, and to provide practitioners with a stepwise procedure to check, analyse and work constantly towards improving the energy performance in water and wastewater utilities. The Guidelines are the main output of the ACWUA WANT project to assist ACWUA and its Tasks Force Energy Efficiency in:

• developing regional guidelines on energy checks and energy analysis (EC+EA) • training of regional EC and EA experts on guidelines and their application • testing the guidelines in pilot utilities (water and wastewater in separate phases) • promoting its application in the MENA region • increasing knowledge and sharing experiences in Energy Management Systems and En-

ergy Audits.

We aim to accomplish these activities by the end of 2015. The process will be i terative, i.e. we will have a feed-back of results from pilot utilities in order to amend the guidelines, and there will be again peer review sessions in mid-2015 to ensure that the Guidelines reflect the state-of-knowledge and of-fer you a hands-on step-by-step guide to achieve your energy targets in the utility. To be fit for the fu-ture will require qualified external energy auditors as well as committed staff in the water utilities, sup-ported by a coherent energy policy at country and energy strategy at company level.

Abdellatif Biad, Chairperson of the ACWUA Task Force (ONEE, Morocco)

Thomas Petermann, ACWUA WANT project manager (GIZ Eschborn, Germany)

Energy Efficiency Guideline for Water and Waste Water Facilities

Page 3


Page - 4 -

Foreword

The main objective of the Arab Countries Water Utilities Association (ACWUA) is to establish a

strong, regional, self-sustainable association of water supply and sanitation utilities in Arab coun-

tries. Furthermore, the ACWUA helps its members to improve their performance in the delivery of

water supply and sanitation services. In order to achieve the association goals the ACWUA initiat-

ed interdisciplinary technical working groups comprising qualified experts from ACWUA members

to deal with specific issues in different priority areas of the water sector:

ELAC - Effective Leading and Communication in Water Utility Management

NCCG - Negotiation and Cross Sectoral Coordination for Enhanced Water Governance

PIAS - Key Performance Indicators and Benchmarking

BPQS - Enhancing Business Performance of Water Utilities through Quality Management and

Standards

One summarising result of supporting these technical working groups and the program: “Strength-

ening the MENA Water Sector through Regional Networking and Training (ACWUA WANT)” is this

Guideline. It describes the benefits of energy efficiency in water and waste water systems and the

process of developing and implementing strategies, using real-world examples, for improving en-

ergy efficiency. The Guideline is based on German energy guidelines and International and Euro-

pean standards, but it is aimed at the Middle East and North Africa (MENA) water sector, because

there is currently no common method of evaluating the energy efficiency in water and waste water

systems.

It is designed to be used by external experts in cooperation with the facilities operators. The Guide-

line provides information, which can be used as a basis for discussing energy management goals

or a benchmarking system with water and waste water treatment facilities managers in a further

step. Furthermore, this Guideline should be used during the design or modification of water and

waste water facilities with regard to the energy efficiency.

Imprint phone.: (49) 0241 50 00 05 fax.: (49) 0241 40 10 04 44 web: www.tuttahs-meyer.de email: [email protected]

------------------------------------------------------ - Bismarckstrasse 2-8, 52066 Aachen -Germany- November 2014


Page - 5 -

Contents

1 Introduction ............................................................................................................ 9

1.1 Background .............................................................................................................. 9

1.2 German Guidelines, European and International Standards ..................................... 9

1.3 Program.................................................................................................................. 10

1.4 Project Partners ...................................................................................................... 10

2 Definitions ............................................................................................................. 11

3 Scope .................................................................................................................... 14

4 MENA Water Sector .............................................................................................. 15

5 General Approach ................................................................................................ 16

6 Requirements for Energy Check and Energy Analysis ...................................... 17

6.1 Administrative Preparations .................................................................................... 18

6.2 Study Parameter Definition ..................................................................................... 18

6.3 Data Validation ....................................................................................................... 19

6.4 Facility Inspection ................................................................................................... 19

7 Energy Check ........................................................................................................ 20

7.1 Key Performance Indicators .................................................................................... 20

7.2 Energy Mapping ..................................................................................................... 22

8 Energy Analysis .................................................................................................... 22

8.1 Energy Balance ...................................................................................................... 23

8.2 Evaluation of the Energy Balance ........................................................................... 26

8.3 Establishment of Actions ........................................................................................ 27

8.3.1 Economic Efficiency Analysis of the Actions ........................................................... 27

8.3.2 Prioritisation of the Actions ..................................................................................... 28

8.3.3 Definition of an Action-Plan..................................................................................... 29


Page - 6 -

9 EnMS and Benchmarking as further steps ......................................................... 30

9.1 EnMS...................................................................................................................... 30

9.2 Benchmarking ......................................................................................................... 30

10 Good Practise and Further Examples of Energy Saving Potentials .................. 31

10.1 Good Practise in the MENA Region ........................................................................ 31

10.1.1 Tunisia .................................................................................................................... 31

10.2 Further Examples ................................................................................................... 32

10.2.1 Energy Efficiency Motors ........................................................................................ 32

10.2.2 Efficiency Pumps and Pump Control ....................................................................... 33

10.2.3 Aeration of Activated Sludge ................................................................................... 34

10.2.4 Efficiency Mixer with CFD Simulation Software ....................................................... 35

10.2.5 Hydropower Turbine ............................................................................................... 35

10.2.6 Solar Thermal Systems in Desalination .................................................................. 36

10.2.7 Photovoltaics .......................................................................................................... 37

10.2.8 Cooling with Heat.................................................................................................... 38

10.2.9 Electrical Load Management .................................................................................. 39

10.2.10 Anaerobic Sludge Treatment .................................................................................. 39

11 Bibliography .......................................................................................................... 40

List of Figures

Figure 1: Coherence of the generic terms .............................................................................. 12

Figure 2: Scope of the Guideline with water supply and waste water disposal ....................... 14

Figure 3: The MENA Region .................................................................................................. 15

Figure 4: General approach for an examination of the energy situation in water supply and

waste water treatment plants ................................................................................. 16

Figure 5: Example for a frequency distribution ....................................................................... 21

Figure 6: Requirements of technical expertise ....................................................................... 22


Page - 7 -

Figure 7: Examples for pie charts in water supply (left) and waste water treatment (right) ..... 25

Figure 8: Pareto chart ............................................................................................................ 32

Figure 9: Specification of energy efficiency according to the IEC 60034-30 [10] .................... 33

Figure 10: Example for a CFD simulation ................................................................................ 35

Figure 11: Impulse hydropower turbine .................................................................................... 36

Figure 12: Reaction hydropower turbine .................................................................................. 36

Figure 13: Solar thermal systems ............................................................................................ 37

Figure 14: Solar systems ......................................................................................................... 38

List of Tables

Table 1: Implementation difficulties and possible solutions .................................................. 17

Table 2: Key Performance Indicators for Energy Check ...................................................... 21

Table 3: Short example of the evaluation in WWTP with theoretical values ......................... 26

Table 4: Example list of actions ........................................................................................... 29

List of Abbreviations

abbreviations description CFD computational fluid dynamics

CHP combined heat and power

EnMS energy management system

HVAC heating, ventilation and air conditioning

KPI key performance indicators

PV photovoltaic

WWTP waste water treatment plant


Page - 8 -

List of Symbols

symbols description unit

A surface / area [m²]

E power consumption per year [kWh/a]

EA power consumption aeration per year [kWh/a]

EB caloric value of the biogas [kWh/m³]

EEP total energy production per year [kWh/a]

esp specific energy consumption -

g gravity [m/s²]

h manometric head [m]

I amperage [A]

i weighted average cost of capital [%] Iinvest investment costs -

n depreciation period [a]

NCHP rate of biogas use in the CHP [%]

NPSH net positive suction head [m]

p pressure [Pa]

P rated power capacity [kW]

PTBOD, 60 inhabitants and popul ation equivalents in total (60 g BOD / PT)

[PT]

Q amount of water per year [m³/a]

QB volume of biogas per year [m³/a]

QL airflow rate per hour [Nm³/h]

QS amount of sludge per year [m³/a]

t operation hours [h]

T temperature [K]

TDH total dynamic head [m]

V voltage [kV]

v volume [m³]

ρ density [kg/m³]

ηa efficiency of the blower [%]

ηEl electric efficiency [%]

ηM efficiency of the engine [%]

ηP efficiency of the pump [%]

ηTh thermal efficiency [%]


Page 9

1 Introduction

1.1 Background

Water and w aste water systems are signifi-

cant energy consumers and the water-energy

issues are of growing importance, because

the operating cost of water supply and waste

water treatment plants are determined by the

energy costs to a large part.

The energy costs are increasing strongly

world-wide. As a result the incentive for ener-

gy efficiency grows. In Germany the topic of

energy in the water sector is important for

several decades and with the help of various

German Guidelines so far, many Energy

Analyses were implemented in the field of

wastewater disposal and water supply. With

these projects much energy could be s aved

in the water sector.

The energy is typically required for all pro-

cess stages, but facilities are not designed

and operated with energy efficiency as a chief

concern. The water and waste water sector

also provides many options to reduce energy

consumption, improve the energy efficiency

and increase its own energy production.

To exploit these potentials, the complex op-

erational procedures in waste water treatment

and water supply require systematic methods

of evaluating the energy efficiency. Perform-

ing Energy Check and E nergy Analysis at

water and waste water treatment plants is a

way to identify opportunities to save money

and energy. The next step after the Energy

Check and the Energy Analysis could be the

implementation of an Energy Management

System (EnMS) and a Benchmarking, but is

not the focus of this Guideline. So this Guide-

line recommends a tiered approach:

1. Energy Check as a stand-alone process

with hints for the need of an Energy

Analysis. Note: The first Energy Check

always leads to an Energy Analysis.

2. Energy Analysis including the Energy

Check

3. Energy Management System (EnMS)

and Benchmarking as optional further

steps

The principle for all energy efficiency actions

is: The improvement of the energy efficiency

should not conflict with the actual purpose of

water and waste water treatment with the aim

of water protection. This basic requirement is

valid for the following Guideline. Furthermore,

it is important to consider the local water

quality and water availability.

1.2 German Guidelines, European and International Standards

Considerations for energy efficiency in

wastewater treatment plants have a long tra-

dition especially in Germany. These experi-

ences developed a w ide range of tools. For

waste water treatment plants that are particu-

larly the Energy Check and the Energy Anal-

ysis. International approaches are developed

besides with the aim to analyse the reduction


Page 10

of the energy consumption. It should be not-

ed that other terms are used in these interna-

tional Guidelines, than described in chapter 2.

This Guideline refers to experiences and the

general approach of German guidelines in

water supply and waste water and to Interna-

tional and European standards. The ap-

proach of this Guideline is based mainly on

the DWA-A 216.

German Guidelines

• DWA-A 216 (2013): “Energy check and

energy analysis – tools for energy opti-

mization of waste water plants“ [1]

• DVGW and German Federal Environ-

mental Foundation (2010): “Guideline

energy efficiency and energy saving in

water supply” [2]

• Ministry for Climate Protection, Environ-

ment, Agriculture, Nature Conservation

and Consumer Protection of the German

State of North Rhine-Westphalia (1999):

“Energy in waste water treatment plants”

[3]

• DWA Landesverband Baden-

Württemberg (2014): “Reduction of elec-

tric consumption for waste water treat-

ment plants” [4]

European and International Standards

• ISO 50001 : “Energy management sys-

tems - Requirements with guidance for

use” [5]

• DIN EN 16247-1: “Energy audits - Part 1:

General requirements” [6]

1.3 Program

This Energy Guideline is based on the pro-

gram - Strengthening the MENA Water Sec-

tor through Regional Networking and Training

“ACWUA-WANT” from ACWUA and the GIZ

(Deutsche Gesellschaft für international

Zusammenarbeit GmbH). The program ena-

bles to manage resources by applying princi-

ples of good water governance and bes t

practices to water supply in urban areas. One

of the goals is the support of regional organi-

sations in the context of network manage-

ment as well as regional exchange and

providing corresponding professional capacity

building services.

1.4 Project Partners

ACWUA

The Arab Countries Water Utilities Associa-

tion (ACWUA) is registered as a non-

governmental & non-profit association (NGO)

and was founded in 2006 as a result of an

initiative by key water sector representatives

in the Arab Region. This organisation has a

mandate to advocate the effective and e ffi-

cient use of water resources as well as to

build capacity in the water sector ensuring

sufficient trained human resources to operate

and maintain the water infrastructure and

improve overall service quality and delivery.


Page 11

GIZ

GIZ is a German federal enterprise and as-

sists the German Government in achieving its

objectives in the field of international coop-

eration and operates in more than 130 coun-

tries worldwide. The GIZ operates in many

fields: economic development and e mploy-

ment promotion; governance and democracy;

security, reconstruction, peacebuilding and

civil conflict transformation; food security,

health and bas ic education; environmental

protection, resource conservation and climate

change mitigation.

TUTTAHS & MEYER

TUTTAHS & MEYER Ingenieurgesellschaft

mbH is a German company which was

founded in 1948. The company provides en-

gineering and consulting services for the en-

tire water management cycle, from planning,

design and c onstruction supervision to site

management and operation. One focus is on

energy in the field of water supply and waste

water treatment with issues in energy effi-

ciency, energy analysis, renewable energies

and energy management systems.

aquabench

aquabench GmbH was founded by German

utilities of the drinking water and t he waste

water sector, which have used benchmarking

as a continuous management tool since

1996. Today aquabench offers a wide range

of benchmarking projects for the whole water

sector. To this Guideline, aquabench contrib-

uted the definitions of the data variables for

the Key Performance Indicators used within

the Energy Analysis, advice regarding their

interpretation and practical solutions for im-

plementation.

2 Definitions

This chapter gives an overview of the main

definitions based on the general approach of

this Guideline. The generic terms and their

coherence are shown in Figure 1. Further

definitions within the scope of water supply,

waste water disposal and ener gy can be

found in ACWUA Wiki [7] or in general defini-

tions and will not be listed here.

Energy Efficiency

Something is more energy efficient if it deliv-

ers more services for the same energy input,

or the same services for less energy input.

Energy Check

The Energy Check is a first estimation of the

energy with the use of a few and very simple

Key Performance Indicators to acquire with

the aim to discover trends in energy efficiency

and determinate components with a high pri-

ority (Energy Mapping). This determination of

the organizations’ energy performance based

on data and other information is leading to

the Energy Analysis. The Energy Check

should be i mplemented every year by the

facilities operators without the help of external

experts. So in the first implementation it is the

first step before the Energy Analysis, but after


Page 12

the Energy Analysis it is a “Stand Alone” Pro-

cess and gives a hint if a new Energy Analy-

sis is needed.

Energy Analysis

The Energy Analysis is an evaluation of the

energy performance which goes more into

detail than an E nergy Check and considers

the construction work, the process as such,

the equipment, operation modus and status

of maintenance. It is based as a second step

on the results of the Energy Check, to take up

recognized gaps and failures.

Energy Audit

In association with the Energy Analysis the

term Energy Audit is often used. The Energy

Audit is defined from international norm [6] as

a systematic inspection and analysis of ener-

gy use and ener gy consumption of a s ite,

building, system or organization with the ob-

jective of identifying energy flows and the

potential for energy efficiency improvements

and reporting them. Energy Audits in this con-

text are a similar process to the Energy Anal-

ysis or Energy Review but may be m ore

comprehensive, including all facilities, build-

ing systems and the organization and ar e

usually done f rom independent external (or

internal) experts.

Energy Management System

An Energy Management System (EnMS) is a

system with a PDCA-cycle (Plan-Do-Act-

Check) for facilities in relation to energy effi-

ciency with tools to monitor, control and opti-

mize the performance of the system. The

Energy Check, Energy Analysis and the En-

ergy Audit are a part of the EnMS.

Figure 1: Coherence of the generic terms

Efficiency Improvement

Adm

inis

trat

ion

for

cont

inuo

us im

prov

emen

t

Energy Check KPI – Energy Mapping

Energy Analysis Energy Balance – Theoretical Values - Actions

– Monitoring

Energy Audit

1

2

3

further Steps: Benchmarking, EnMS


Page 13

Benchmarking

Benchmarking is a tool for performance im-

provement through systematic search and

adaptation of leading practices. Benchmark-

ing with focus on energy efficiency is an op-

tional step, involving not just one single oper-

ator but a group of operators. It supports the

work on ener gy efficiency by learning from

experiences and technologies already used

by partner operators making use of systemat-

ic comparisons of performance indicators to

reference values from partner operators.

Key Performance Indicators

Key Performance Indicators (KPI) are an in-

strument of performance measurement in the

Energy Check. Key performance indicators

measure the performance of machines, facili-

ties or installations and thus allow specifying

the progress of conformance with regard to

objectives, to compare similar facilities or

working orders and evaluate success. Build-

ing KPI means to set variable data in relation

to basic (also variable) values.

Energy Mapping

Energy Mapping is the determination of areas

or single consumers that have a s ignificant

deviation in their energy consumption.

The results of the Energy Check including the

definition of KPI make it possible to determine

such areas with a s ignificant consumption.

This analysis is useful to focus on such rele-

vant consumers.

Energy Balance

An Energy Balance is the complete Listing of

all energy consumers in relation to the total

input of all energies with their type, year of

construction, operating hours, rated power

capacity, power consumption, frequency con-

version and energy consumption divided into

process steps.

Theoretical Values

Theoretical Values for the Energy Consump-

tion in the Energy Analysis are based on ex-

perience, technical calculation rules and doc-

umented performance of machines. These

theoretical values determine and quantify the

main influences on ene rgy consumption and

production. They also allow an indication of

what level of energy efficiency can be

achieved for the given boundary conditions

on the facility.


Page 14

3 Scope

This Guideline concentrates on the process

of Energy Check and Energy Analysis with

only hints on a further implementation of an

Energy Management System and a B ench-

marking Systems. Therefore the EnMS and

the Benchmarking process, as a single pro-

cess, are not described in detail. The scope

of this Guideline includes the system of water

supply and waste water disposal (Figure 2)

with the focus on:

• water abstraction • raw water transmission • water treatment • water storage • drinking water transmission • drinking water distribution • waste water collection • waste water transmission • waste water treatment

• sludge treatment • water reuse • energy recovery

In general, this Guideline may be us ed for

industrial waste water treatment plants if the

specific procedures and the water pollution

are considered.

The results and the data collected during the

implementation of the Energy Check and the

Energy Analysis can be used to create a

transnational database in a nex t step and

improve statistical analyses in future.

Figure 2: Scope of the Guideline with water supply and waste water disposal

Energy Recovery

Waste Water Disposal

Water Supply

Water Abstraction Raw Water Transmission

Water Treatment

Waste Water Collection Waste Water Treatment

Sludge Treatment

End User Drinking Water Storage Drinking Water

Distribution

Water Reuse

Waste Water Transmission

Drinking Water Transmission


Page 15

4 MENA Water Sector

The MENA (Middle East & North Africa, see

Figure 3) region is the most water scarce

region in the world. Worldwide, the water

availability per person is up t o 7,000

m3/person/year. In the MENA region it is only

about 1,200 m3/person/year. Half of the popu-

lation live under conditions of water stress.

The problems are water scarcity, water pollu-

tion and q uality; the lack of funding re-

sources, cost recovery and insufficient asset

management. Furthermore, the water and

waste water systems are high energy con-

sumers and have to face increasing energy

costs today.

The source of water and the water quality

varies from country to country. Some coun-

tries surface water from rivers and others

gain water almost entirely from groundwater

and desalination. The technique in water

supply and waste water treatment also varies

from country to country. The relevant tech-

nologies in these areas are shown below,

without any guarantee of completeness:

Water Supply

• pumping (wells, rivers, sea etc.) • iron exchanger • aeration • ozonisation • UV radiation • filtration • desalination • sludge dewatering (thickener, filter-

press, centrifuge etc.) • water storage • pumping – pressurisation


• waste water pumping • activated sludge treatment • anaerobic waste water treatment • anaerobic and aerated lagooning • constructed wetland • rotating biological contactor • biological filtration • UV radiation • ozonisation • aerobic sludge treatment • anaerobic sludge digestion • sludge dewatering (thickener, filter-

press, centrifuge etc.)

Figure 3: The MENA Region


Page 16

5 General Approach

The general approach for an examination of

the energy situation in water supply and

waste water disposal is based on the simple

principle: “From coarse to the fine”.

For the first consideration of a facility an En-

ergy Check should be conducted with easy to

determine KPI. Evaluating these KPI and

comparing them with other facilities makes it

possible to identify the first energy saving

potentials and plan actions. Also the areas or

facilities to put focus on (Energy Mapping)

can be determined.

In an Energy Analysis it might be sufficient to

check machines with a low rated power ca-

pacity with an estimated calculation (see

chapter 8). Checking all the components

with measurements for an Energy Balance of

the facility takes a great deal of time and the

technical documentation often doesn’t exist.

The evaluation of the Energy Balance should

be compared with the Theoretical Values for

every process step or machine.

This usually leads to actions to improve ener-

gy efficiency. The actions have to be docu-

mented during realization and for control after

implementing according to the following as-

pects:

• action description • responsibility • start of the action • planned duration • current duration • measures implemented to monitor

success • reasons for aborting the action • cost benefit calculation • real energy saving every year

Energy Check limited data collection First Actions

Energy Balance extended data collection

Evaluation of Energy Balance with Theoretical

Values

Monitoring

Energy Analysis

Establishment of Actions and new

Measurement

Realisation of the Action-Plan

Figure 4: General approach for an examination of the energy situation in water supply and

waste water treatment plants


Page 17

It is now important to check the success regu-

lar with new measurement and monitoring. A

monitoring strategy on the facilities is used for

the actual comparison of the recorded meas-

urement values with the plant-specific KPI.

The important questions to implement a

monitoring system are:

• What measurement already exists ? • Is this measurement plausible ? • What further measurements are

needed?

The realization of a monitoring concept into

the process control system requires a more

detailed planning and t he installation of the

measuring points on the facilities with differ-

ent levels of effort. The realization of the ac-

tions and the monitoring are not part of the

Energy Analysis.

The general approach is not separated into

water supply and waste water treatment. Only

the components and machines in the several

steps of the process vary as a part of the de-

tailed Energy Analysis. An operating plan is

provided in the appendix with every step dur-

ing the implementation.

6 Requirements for Energy Check and Energy Analysis

The success of an Energy Check and an En-

ergy Analysis depends on the technical ex-

pertise of the persons who perform the as-

sessment. Also the reliability and availability

of data have an influence on the success.

Furthermore, it is important to include the

operating personnel’s experience in order to

increase the acceptance of possible changes.

Some very important information are only

available by questioning the operating staff.

In the implementation process, difficulties

often occur which are listed in Table 1 with a

solution proposal.

The following requirements are valid for the

Energy Check and the Energy Analysis. Re-

quirements only for the Energy Check or the

Energy Analysis are described in the relevant

chapters 7 and 8.

Table 1: Implementation difficulties and possible solutions

Implementation difficulties Possible solutionsCapacity building program within utilities (internal training of staff)Run a pilot on a small scaleLeadershipInvolvement and back-up by top-managementAssign clear resources (budget, personnel) to the energy efficiency teamNominate energy officerStart and improve little by littleUse pilot data collection for restricted time span as first stepEstablish data collection procedures for indicators ranked high priorityStart and improve little by littleIntroduction of accuracy bands and reliability bands for indicatorsPreparation of cost–benefit analysesPrioritisation of measures according to highest return on investment

Lack of expertise

Lack of awareness and commitment among the staff

Data availability

Data accuracy and reliability

Lack of financial resources


Page 18

6.1 Administrative Preparations

Before a water or waste water treatment plant

can implement an Energy Check or an Ener-

gy Analysis, the operating staff must take the

time to establish a strong team and set the

tasks for everybody.

First, it is important to decide which facilities

should be ex amined and w ho will lead the

whole project. After that the facilities should

establish their energy policy and overall en-

ergy improvement goals. All these determina-

tions have to be w ritten down as a master

plan. The overall energy improvement goals

can be fixed with more evidence after execu-

tion of Energy Checks and even more after

Energy Analysis.

The knowledge required operating a w ater

supply or waste water treatment plant is suffi-

cient to perform an Energy Check. Only for

the Energy Analysis it is important to search

for external experts.

6.2 Study Parameter Definition

The definition of the boundaries is very im-

portant when defining the components and

process steps in water supply and waste wa-

ter disposal so as to make a comparison with

other facilities.

The boundaries should be defined in:

• area focus • assessment period • energy sources

Area Focus

The local boundary means the definition of

the process and the components which are to

be estimated (see Figure 2). In the Energy

Analysis every component will be examined

separately so that it is possible to summarize

the energy consumption or separate them in

every process step. For the Energy Check it

is useful to set boundaries for the Key Per-

formance Indicators to get the same basis for

every Energy Check.

Water Supply:

• water treatment (including water abstraction without pure water pumping)

• water distribution (pure water pumping)

• water distribution (pressurization including water stor-age)

• energy production

Waste Water Disposal:

• waste water treatment (including aera-tion and sludge treatment and without water collection and waste water transmission)

• waste water treatment aeration • waste water pumping stations • energy production

Assessment Period

In general an Energy Check and an Energy

Analysis have an assessment period of one

year. But it is important to check special

events in this year and historical and season-


Page 19

al events in order to obtain a representative

impression of the facility. For example, there

may have been unusual machine stoppages,

making the total power consumption lower

than normal. In such cases it is advisable to

adjust the total power consumption in line

with the theoretical consumption of these

machines during the Energy Analysis.

Energy Sources

All energy sources entering and exiting the

local and t emporal boundary and are con-

verted in electrical energy of the facility need

to be assessed:

• electric energy and fuels, gas into fa-cility

• water flow (hydropower) • organic solids (digestion) • other renewable energy (solar, wind

etc.)

The Energy Check and The Energy Analysis

need the total number of inhabitants and

population equivalents. In German guide-

lines, the total number of inhabitants and

population equivalents is related to the daily

COD (chemical oxygen demand) load for

Energy Check and E nergy Analysis. In the

MENA water sector the daily BOD5 (biochem-

ical oxygen demand in five days) load is nor-

mally measured and should be used with the

factor:

1 PT = 60 g BOD5/d

The load has to be measured at the entrance

as the average load of the WWTP without

any reflux from the sludge treatment (or from

sludge drying bed). For example if you have a

yearly load of 2,190 t BOD5/a, your PT is:

2,190 t BOD5/a·1,000/365 = 6.000 kg BOD5/d

6.000 kg BOD5/d/0.06 kg BOD5/(PT·d)

= 100,000 PT

This factor does not represent the load on the

waste water treatment plant in relation to all

aspects, but ensures an energetic compara-

bility if every facility uses the same factor of

60 g/(PT·d).

6.3 Data Validation

The data collected has to be v alidated, be-

cause often the data is not reliable. This

takes into account the operating data of the

water flows, water quality, water losses,

waste water load, biogas production etc. and

of course the entire energy data. The valida-

tion in the Energy Analysis has to be c on-

firmed by the external experts with knowledge

about the facility in cooperation with the op-

erators.

6.4 Facility Inspection

After receiving and validating the data and

checking it for plausibility, the next step is to

conduct a facility inspection to

• check the current conditions, • take meter readings, • determine optional measurement

campaign for collecting additional da-ta,


Page 20

• inspect and verify equipment infor-mation,

• take photo documentation, • review the materials collected • and interview operators.

The steps of the process, the construction of

the facility of water supply or waste water

treatment and the results of the facility in-

spection have to be written down in the ener-

gy report if they are relevant to the energy

tasks. The process steps have to be illustrat-

ed in a flow chart with all relevant flows (wa-

ter, waste water, sludge etc.).

7 Energy Check

An Energy Check is conceived as a monitor-

ing tool, which can be appl ied by the own

staff with easily available data. The Energy

Check should be done every year and gives

hint about deviations and the need for a fur-

ther Energy Analysis.

For the MENA water sector it is important to

collect this data first and consolidate the data

centrally, because currently there is no local

data for a comparison. The Energy Check

should be implementing without measure-

ments. If the data cannot be collected nor it is

plausible, it can be useful to install fixed

measurement for some facility components

(for example pumping stations, aerations) in

order to implement the Energy Check every

year by the operators.

7.1 Key Performance Indicators

The following data is necessary to calculate

the Key Performance Indicators:

Water Supply:

• water quantity in water abstraction [m³/a]

• total power consumption of the facility per year [kWh/a]

• total power consumption of the pure water pumping station per year [kWh/a]

• total power consumption of every oth-er pumping station per year [kWh/a]

• total energy production per year [kWh/a]

Waste Water Disposal:

• total number of inhabitants and popu-lation equivalents [PT]


• total power consumption of the aera-tion per year [kWh/a]

• total electricity production of combined heat and power (CHP) per year [kWh/a]

• total energy production per year from other energy sources [kWh/a]

• total power consumption of every oth-er pumping station per year [kWh/a]

For the first orientation concerning the energy

efficiency of the facilities, the KPI collected in

Germany could be us ed with the statistical

frequency distribution of existing waste water

treatment plants. The scope of water supply

does not have such frequency distribution or

reference values.


Page 21

The following KPI for the Energy Check are

separate in water supply and waste water

disposal in Table 2. The reference for the

water supply is the amount of water abstrac-

tion or the water being pumped in m³/a. For

waste water disposal the reference is the total

number of population equivalents in PT or the

amount of water being pumped with the man-

ometric high (see chapter 6.2).

To illustrate the comparison with the German

frequency distributions, the Figure 5 shows

an example for the specific power consump-

50 %

80 %

0102030405060708090

100

0 10 20 30 40 50 60 70 80

[%]

[kWh/(PT·a)]

specific power consumption aeration

frequency distribution Median KPI of the facility

Table 2: Key Performance Indicators for Energy Check

Water Supply Calculations

1 specific power consumption per facility [kWh/(m³)] esp = E/Q

2 specific power consumption pure water pumping station [kWh/(m³ · m)] esp = E/Q/h

3 specific power consumption of every other pumping station [kWh/(m³ · m)] esp = E/Q/h4 level of self-supply electricity [%] VSSE = (EEP/E)·100

E= power consumption per year [kWh/a]

Q = amount of water per year [m³/a]

h = manometric head [m] EEP = total energy production per year [kWh/a]

Waste Water Treatment Calculations

1 specific power consumption per facility [kWh/(PT · a)] esp= E/PTBOD,60

2 specific power consumption aeration [kWh/(PT · a)] esp = EA/PTBOD,60

3 level of self-supply electricity [%] VSSE = (EEP/E)·100

4 spezific power consumption of pump stations [kWh/(m³ · m)] esp = E/Q/h

E = total power consumption per year [kWh/a]

PTBOD,60 = total number of population equivalents [PT]

EA = power consumption of the aeration per year [kWh/a]

EEP = total energy production per year [kWh/a] (CHP and other energy sources)

Q = amount of water per year [m³/a]h = manometric head [m]

Figure 5: Example for a frequency distribution


Page 22

tion of aeration. Assuming that the facility has

a KPI for the aeration of 32 kWh/(PT·a) the

energy consumption is twice as high as the

median of 15 kWh/(PT·a). So there could be

a high energy saving potential in the process

of aeration.

7.2 Energy Mapping

With the result of the Energy Check, the facili-

ty inspection and t he interviews with the op-

erating staff, it could be useful to determine

areas with a higher need of energy efficiency

and focus them during the Energy Analysis.

For example, if there are Energy Checks for

different facilities, the implementation of an

Energy Analysis should be preferred for the

facilities with a high deviation in energy con-

sumption compared to the frequency distribu-

tions. Furthermore if there are high deviations

in aeration (WWTP) or pure water pumping

(water supply), the Energy Analysis should

observed these processes in detail.

8 Energy Analysis

The Energy Analysis should always be im-

plemented after the first Energy Check. After

that the Energy Analysis is only necessary if

there a big deviations, which cannot be r ea-

soned.

Performing a det ailed Energy Analysis de-

mands detailed knowledge and experience in

the field of energy- and water technology (see

Figure 6).

Because all this expertise cannot be provided

by one per son, it is important to compose a

team with several experts (civil engineers,

electrical engineers, process and hydraulic

engineers, business engineers etc.) in close

cooperation with the operators of the facility.

Before the experts conduct a facility inspec-

tion with the associated operators, they

should have the opportunity to look at the

operating data, documentation and pl ans to

get an overview of the facility in advance.

Experts

Waste Water Disposal Water Supply

water abstraction

mechanical, biological and chemical water treatment

water storage and transmission

hydraulics

machine technology

Supervisory Control and Data Ac-quisition (SCADA)

power engineering

utilization of biogas

mechanical, biological and chemical wastewater treatment

sludge treatment

hydraulics

machine technology

Supervisory Control and Data Ac-quisition (SCADA)

power engineering

Figure 6: Requirements of technical expertise


Page 23

The Energy Analysis is composed of four

distinguished steps: the Energy Balance, the

Evaluation of the Energy Balance with the

Theoretical Values, the Establishment of Ac-

tions including the economic efficiency analy-

sis.

The following data, which are needed for the

Energy Analysis are valid for water supply

and waste water disposal and should give a

detailed examination of the facility and are

necessary to calculate the Theoretical Val-

ues.

General information:

• name of the operator and address of the facility

• contact person for energy • energy supply contracts

Process information:

• design report • technical documentation • procedural schemes • piping and instrumentation diagram • operating manual

Operating data of:

• water abstraction (only water supply) • water transmission • water treatment • waste water treatment (only waste wa-

ter disposal) • sludge treatment (digester, dewatering

etc.) • external substrate intake (co-

digestion) (only waste water disposal) • biogas (only waste water disposal)

• energy and material consumption • HVAC systems (heating, ventilation

and air conditioning)

List of machines:

• type • year of construction • operating hours • rated power capacity, cos φ, V, I

and/or power consumption • information about frequency conver-

sion

In addition, for some machines it is necessary

to collect further information like mean and

max output, hydrostatic head, feedback con-

trol etc.

For a national database with more KPI than

listed in the Energy Check it is useful to ex-

tend the KPI from the Energy Check in the

Energy Analysis. These KPI are listed in the

appendix. The definitions of the required data

variables and advice regarding the interpreta-

tion of these Key Performance Indicators are

described in detail in the appendix. All infor-

mation in the appendix chapter “Key Perfor-

mance Indicators of Energy Check” is based

on aquabench experiences and the IWA per-

formance indicator system.

8.1 Energy Balance

In the MENA water sector there is normally

no high demand for heating, except in waste

water treatment plants with anaerobic sludge

treatment in a digester. By using its biogas in

a combined heat and power station or heater,


Page 24

the facility can cover its own heat demand. In

individual cases it could be us eful to take a

look at the heating, but it is difficult to meas-

ure the heat and this would often only be

based on t heoretical assumptions. Thus in

general and in this Guideline the focus is on

the power consumption and production.

To develop the energy balance of the actual

situation all important machines divided into

process steps should be examined individual-

ly. The examination should include their type,

year of construction, operating hours, rated

power capacity, power consumption and fre-

quency conversion. The sum of the power

consumption of all machines should approxi-

mate the actual power purchased plus the

facilities own power production; a deviation of

up to 10 % is acceptable. All machines have

to be listed in a consumption matrix (example

in appendix).

It could be sufficient to start a new measure-

ment campaign before starting the Energy

Analysis. The first question to ask is what

kind of measurement already exists and is

this measurement plausible and what further

measurements are needed. The operator

should compile and ac tual keep a m eter list

for the main data concerning an Energy Anal-

ysis with information about precision and val-

idation activities.

If there is no separate power consumption

counter of the machine, the machine has no

frequency conversion and i t is possible to

measure the actual amperage the power

consumption could be c alculated with the

following equation:

E = V · I · root(3)· cos φ ·t

E = energy consumption [kWh/a]

V = voltage measured phase to phase [kV]

I = amperage [A]

cos φ = power factor [-]

t = operation hours [h/a]

This formula is only valuable, if the power

consumption is constant. For pumps with

variable flow and/or head it is not possible to

use one measurement of voltage and amper-

age even if there is no frequency. These ma-

chines have to be measured during all opera-

tion points (water or sludge flow) and evalu-

ated by the analysis of the operational data.

The amperage can be measured with several

systems. The commonly used method is a

multimeter or clamp meter. This is a s mall

hand-held device that can be used to meas-

ure voltage, resistance, and amperage. It is

helpful to involve an electrical engineer during

the measurements. If no amperage meas-

urement is possible or the measurement

needs a considerable effort which would ex-

ceed the timescale of the Energy Analysis,

the power consumption could be c alculated.

This calculation is based on t he product of

the rated power capacity (P) and the operat-

ing time (t) with a factor of 0.7 to 0.9:

E = P · t · (0.7 to 0.9)


Page 25

This approach is useful especially for small

machines only; because this equation doesn’t

show the real energy consumption and mo-

tors are often largely overdesigned, so that

the formula delivers falsified results. But this

formular is helpful to fill in the gaps during the

development of the energy balance.

For pumping stations or single pumps it could

be sufficient to use the following calculation,

which considers the amount of water being

pumped and the manometric head:

E = Q · ρ · g · h

ηP · 3,600,000

E = energy consumption [kWh/a]

Q = amount of water per year [m³/a]

ρ = density [kg/m³]

g = gravity [m/s²]

h = manometric head [m]

ηP = efficiency of pump [%]

Machines with a v ariable speed/frequency

drive (VSD/VFD) have to be examined in re-

lation to the characteristic performance load

taking into account the transformer’s losses

(2-8%). If there is no considerable volatility,

the power consumption could be m easured

(with the options described before). If there is

a considerable volatility, it is necessary to

measure the amperage in different frequency

ranges and calculate each with the operating

hours in the corresponding power output

range or measure the power consumption

about a representative time (several weeks).

The results of the consumption matrix should

be illustrated in a pi e chart (see Figure 7).

This pie chart forms the basis for the evalua-

tion of the energy balance and indicates en-

ergy saving potentials if there is an unus ual

distribution. Furthermore, the percentage of

the total power consumption used in every

process step can give a hint as to the plausi-

bility. It is very important to analyse this chart

with the knowledge of the process and other

specific conditions.

Figure 7: Examples for pie charts in water supply (left) and waste water treatment (right)


Page 26

8.2 Evaluation of the Energy Bal-ance

In addition to the approach of the Energy

Check, the evaluation of the energy balance

uses ideal theoretical (calculated) values

based on ex perience, technical calculation

rules and documented performance of ma-

chines. These theoretical values determine

and quantify the main influences on ener gy

consumption and production and allow an

indication of the energy efficiency level that

can be achieved for the given boundary con-

ditions on t he facility. The theoretical values

which can be us ed for water supply and

waste water treatment are listed in the Ap-

pendix and based partly on t he DWA-A 216

[1].

When using these first it is important to an-

swer a few questions:

• What machines are important for en-ergy consumption in my facility? Look at the list of machines and the pie chart.

• Which theoretical values can I use for my facility?

• What are the specific units? • What data do I need to calculate the

theoretical values?

After that, every theoretical value of a m a-

chine has to be c alculated separately and

listed together with the actual data measured.

An example is illustrated in Table 3.

The measured or collected data and the theo-

retical values have to be transformed into the

specific unit (kWh/(PTBOD,60·a), kWh/m³) so as

to allow comparison with the KPI. The energy

balance of a facility can be evaluated with a

comparison between the actual data meas-

ured and the theoretical values. Significant

differences indicate an optimization potential.

Table 3: Short example of the evaluation in WWTP with theoretical values

No. Machine Absolut power consumption Percentage Specific power

consumptionTheoretical

Value Difference

[KWh/a] [%] [kWh/(PT·a)] [kWh/(PT·a)] [kWh/(PT·a)]1 pumping station 92,000 16% 6.1 4.5 1.6

pump 1 12,000 0.8 0.5 0.3pump 2 30,000 2.0 1.5 0.5pump 3 50,000 3.3 2.5 0.8

2 screen 28,000 5% 1.9 1.3 0.6screen 1 8,000 0.5 0.3 0.2screen 2 20,000 1.3 1.0 0.3

3 biolocial tank 310,000 54% 20.7 13.0 7.7aeration 250,000 16.7 10.5 6.2stirrer 60,000 4.0 2.5 1.5

4 final sedimentation 9,000 2% 0.6 0.6 0.0scraper 9,000 0.6 0.6 0.0

5 sludge treatment 120,000 21% 8.0 7.0 1.0thickening 15,000 1.0 0.5 0.5digestion 60,000 4.0 3.5 0.5dewatering 45,000 3.0 3.0 0.0

7 infrastructure 15,000 3% 1.0 0.5 0.5power consumption of building 6,000 0.4 0.2 0.2cooling of buildings 9,000 0.6 0.3 0.3

574,000 100% 38.3 26.9total energy consumption


Page 27

The next step is the identification of im-

provement measures for those machines with

high optimization potential. To evaluate as-

sumed optimization potential, the operational

data used needs to be questioned. Especially

in case of constantly running machines and

machines with controlled operation, an exam-

ination of the configured operational settings

is necessary.

8.3 Establishment of Actions

The establishment of action should be based

on the result of the Energy Check and t he

Energy Analysis with the focus on the engi-

neering, operational and procedural analysis.

Furthermore, it is important to consider the

interviews with the operators.

The actions have to be separated into actions

for reducing energy consumption and actions

for optimizing the energy supply:

Reduction of Energy Consumption

Opportunities for improving energy efficiency

in water and waste water systems fall into

three basic categories:

• reduce the energy demand - example: reduction of air entry into the main biological tank, reduce pres-sure losses

• increase the energy efficiency - example: efficiency pumps, examina-tion of the dimensioning

• improve the power factor - example: part load performance

Optimization of Energy Supply

• purchase electricity, heat and fuel cheaper - example: take a look at the energy supply contracts

• increase one’s own energy production /energy recovery - example: CHP, hydro power, wind-energy, solar-energy etc.

• improve the power supply stability (frequency, voltage etc.)

Further examples of actions are described in

chapter 10.2.

8.3.1 Economic Efficiency Analysis of the Actions

In the Energy Analysis it is sufficient to esti-

mate the investment costs (deviation of

± 25 %) and t he energy saving potential of

every action and create the cost-benefit anal-

yses. With this it is possible to pick out the

actions, which could be economic.

The Energy Analysis delivers the evidence of

actions and has to be examined in a f urther

detailed planning. Only with the result of the

detailed planning it is possible to check all the

effects of the implementation and to establish

how big the investment costs really are.

Furthermore, it is recommendable to check

the actions with a sensitivity analysis and look

at what will happen if the energy costs and

the operating costs rise in future.

One opportunity in economic efficiency anal-

ysis is the method of cost comparison, which


Page 28

should be applied to the energy efficiency

actions in this Guideline.

The following aspects should be applied by

the operators for the calculation of annual

costs and annual benefits:

• weighted average cost of capital [%] • depreciation period of building, ma-

chines and electro technique [a]

The annual costs are calculated with the fol-

lowing equation:

Annual costs = IInvest · i · (1 + i)n / [(1 + i)n - 1]

with

Iinvest = investment costs

i = weighted average cost of capital

n = depreciation period

Then the cost/benefit factors have to be cal-

culated from the annual costs and the annual

benefits. If the factor is less than 1, the action

is evaluated as economical.

As an ex ample for an economic efficiency

analysis a combined heat power station with

100 kW electric power and 135 kW thermal

power will be described:

Iinvest = $150,000

i = 3 %

n = 10 a

Annual costs:

$150,000 · 0.03·(1+0.03)10 / [(1+0.03)10 - 1]

≈ $17,600 per year

The Annual benefit will be calculated with an

operating time of 7,300 h/a, a power factor of

0.8 and with energy cost of 10 Cent per kWh

for electricity and 5 Cent per kWh for heat:

Annual benefits:

Electricity:

100 kW · 0.8 · 7,300 h/a · 0.10 $/kWh

≈ $58,000 per year

Heat:

135 kW · 0.8 · 7,300 h/a · 0.05 $/kWh

≈ $40,000 per year

Cost / Benefit factor:

$17,600 / ($58,000 + $40,000) = 0.18

The action is evaluated as economical.

8.3.2 Prioritisation of the Actions

The actions have to be classified into actions

that need to be implemented directly, short-

term and long-term with the focus on the effi-

ciency and the economic efficiency analysis

based on [3] and [1]. The actions have to be

listed with the energy saving potential, the

result of the economic efficiency analysis and

the prioritisation. An example of such a list is

shown in Table 4.


Page 29

Direct Actions

These actions are very profitable and can be

implemented easily without any comprehen-

sive planning effort.

Examples: reduce the backwash time of the

filtration; change switching on and off point of

pumps, optimization of the water storage.

Short-Term Actions

These actions are economical, but they are

associated with investments and need to be

investigated in detailed planning.

Examples: changing the aeration from con-

tinuous to intermittent, changing the operat-

ing of the pumps (count, operation hours

etc.), replacing an older blower with an effi-

cient new one, solar power.

Long-Term Actions

These actions are less economical and relat-

ed to certain conditions, such as the life-cycle

of a machine to be replaced or forthcoming

renovations.

Examples: LED-lighting, changing the aerobic

sludge stabilization to anaerobic with digest-

er.

8.3.3 Definition of an Action-Plan

It is very important to set an action-plan with

the time period for realization of the estab-

lished actions. Maybe the economics of some

actions depends only on t he energy price.

With the increase of the energy price, these

actions could be economical in several years.

Table 4: Example list of actions

No. action

energy saving potentialelectricity

energy saving potential

heat

investment cost

cost/benefit factors prioritisation

O01 backwash time of the filtration 11,000 kWh/a 0 kWh/a $1,000.00 0.05 direct actionO02 optimize exhaust air treatment 5,000 kWh/a 0 kWh/a $2,000.00 0.23 short-term actionO03 LED-Lighting 3,000 kWh/a 0 kWh/a $9,000.00 1.76 long-term actionO04 ventilation with frequency drive 2,000 kWh/a 0 kWh/a $2,000.00 0.59 short-term action

P01 new sludge dewatering 100,000 kWh/a 0 kWh/a $90,000.00 0.53 short-term actionP02 change blower 200,000 kWh/a 0 kWh/a $80,000.00 0.23 short-term actionP03 change pumps 50,000 kWh/a 0 kWh/a $35,000.00 0.41 short-term actionP05 anaerobic sludge treatment 1,000,000 kWh/a 0 kWh/a $1,500,000.00 0.88 long-term actionP06 CHP 500,000 kWh/a 600,000 kWh/a $150,000.00 0.18 long-term action

E01 windpower 350,000 kWh/a 0 kWh/a $520,000.00 0.87 short-term actionE02 photovoltaics 80,000 kWh/a 0 kWh/a $70,000.00 0.51 short-term actionE03 hydro power 40,000 kWh/a 0 kWh/a $30,000.00 0.44 short-term action

operating actions

process actions

actions with renewable energies


Page 30

9 EnMS and Benchmarking as further steps

9.1 EnMS

The Energy Analysis is similar to the "Energy

Review" of ISO 50001, which is the basis for

the implementation of a comprehensive sys-

tem for continuous improvement of energy

efficiency in all areas of an organization.

In addition to the requirements described in

this Guideline an EnMS needs more determi-

nations in responsibility, communication and

long term energy strategies as well as in the

internal tasks, processes in the departments

for staff training, purchasing and planning of

new buildings and facilities.

The management cycle (PDCA Plan-Do-

Check-Act) is amplified by a r egular internal

audit with the technical improvements and the

search for optimization potential in the pro-

cesses.

At the end o f each cycle, an i ntense man-

agement review is required based on the

monitoring data and the audit result, in which

all major decisions for the upcoming assess-

ment period (usually one y ear) are taken.

Special guidelines which describe the imple-

mentation of an EMS already exist:

• GUTcert Certifizierungsgesellschaft, Ber-

lin: “Guideline to Efficient Energy Man-

agement according to ISO 50001 / Guide

pour un management efficace de l'éner-

gie selon ISO 50001”, Version 4.2 2014

(EN/FR/GER and other languages) [8]

• German Federal Ministry for the Envi-

ronment, Nature Conservation and Nu-

clear Safety (2012): “Energy Manage-

ment Systems in Practice - ISO 50001: A

Guide for Companies and Organisations

[9]”

9.2 Benchmarking

Benchmarking in the water industry is a well-

known practice. Various national benchmark-

ing initiatives exist already in MENA region

(with a focus beyond energy efficiency). The

International Water Association (IWA) has

defined its goals and the main steps.

‘Benchmarking is a tool for performance im-

provement through systematic search and

adaptation of leading practices.’ [10]

It consists of two fundamental components:

performance assessment and per formance

improvement.

Performance assessment in benchmarking is

based on the evaluation of performance indi-

cators as used for the Energy Check. How-

ever, in a benc hmarking initiative values of

performance indicators are rather compared

to values of other similar partners than inter-

nally to historical values of the same utility.

Such comparison is possible, if the different

technologies and context of each benchmark-

ing partner are taken into account. By doing

so, it is possible to find improvement poten-


Page 31

tial. It might be the case, that others perform

already much better than own plants or as-

sets. Those partners might have already in-

stalled “good practices” from which the under-

taking wants to learn.

Thus, using the developed energy KPI in a

Benchmarking initiative may support the work

on energy efficiency in three ways:

• learning from experiences and tech-niques already used by partner operators

• comparing in a structured way to refer-ence values of partner operators

• building up a database of energy related reference values of the MENA region

ACWUA’s Benchmarking Technical Working

Group (TWG) consolidates all knowledge on

benchmarking for the MENA region and o f-

fers additional tools and support.

10 Good Practise and Further Ex-amples of Energy Saving Po-tentials

This chapter demonstrates good practice

examples in the MENA region and some cho-

sen examples for actions in the field of ener-

gy efficiency and energy production in water

supply and waste water treatment. These

examples can be used as a basis to identify

areas for improvement.

10.1 Good Practise in the MENA Region

10.1.1 Tunisia

SONEDE’s (National Water Distribution Utili-

ty) mission is to supply drinking water to the

country. It is responsible for the development,

operation, maintenance and renewal of facili-

ties for the collection, processing, transfer

and distribution of water.

SONEDE has worked for decades on the

establishment, extension and maintenance of

a diverse and c omplex hydraulic infrastruc-

ture covering the whole country with a c om-

bined length of 50,000 km of water pipelines

and with 1,300 pumping stations and 1 ,000

tanks which has achieved a coverage rate of

100% in urban and 93.5% rural areas.

This huge infrastructure requires large

amounts of energy to ensure the production,

transfer and di stribution of water, which

makes SONEDE one of the largest consum-

ers of energy in Tunisia.

In fact, during the year 2013, its consumption

reached 360 GWh of electricity (26 million

Euros) which represents 20% of the turnover

of the company. In addition to its water saving

potential, SONEDE has developed a strategy

in the fields of energy efficiency and renewa-

ble energies.

In the field of energy efficiency, SONEDE has

planned several actions in pumping and wa-


Page 32

ter production stations and in administrative

buildings. These actions consist of the:

• completion of Energy Audits, • installation of equipment and the use

of technologies to improve the energy efficiency and pressure control (e.g. speeds drives),

• reducing pressure losses and pres-sure dissipation,

• equipment upgrades, • developing a maintenance program • installation of intelligent systems to

optimize pumping schedules, • implementation of an energy man-

agement system in accordance with ISO 50001

• and training and information to ensure regular and sustained continuous awareness of all actors in the energy efficiency field in SONEDE.

In the field of Energy Audits and given the

large number of stations, SONEDE has fo-

cused on external energy audits in major and

medium pumping stations and realized inter-

nal auditing for smaller stations. The cumula-

tive distribution of energy as a function of the

accumulated number of stations is shown in

the form of a Pareto chart (Figure 8).

Figure 8: Pareto chart

10.2 Further Examples

The following actions are only examples

without any guarantee of the completeness or

the applicability for every facility. Of course

there are many more opportunities, which

could be i dentified during the Energy Analy-

sis.

Before implementing such energy saving ac-

tions it is important to train the operators in

these energy efficiency techniques.

10.2.1 Energy Efficiency Motors

Every machine in the water sector has a spe-

cific energy-efficiency depending on the mo-

tor. The aim for every machine is to achieve

the best specific energy efficiency possible.

The classification of the energy efficiency is

based on the IEC 60034-30 [11]. The IEC

60034-30 specifies energy-efficiency classes

for single-speed, three-phase and cage-

induction motors with 2, 4 or 6 poles (Figure

9). It classifies three classes:

• IE1 (standard) • IE2 (high) • IE3 (premium)

The difference in the specific energy efficien-

cy depending on the rated power capacity

and the pole can be 2 % to 9 %.

For example a m achine with 100 k W rated

power capacity and 8,760 operating hours

per year has an ene rgy consumption of

about:


Page 33

100 kW · 8,760 h/a · 0.8 = 700,000 kWh/a

The replacement of the motor with an IE3

saves the following energy consumption:

700,000 kWh/a · 0.02 = 14,000 kWh/a

It is important to look at the lifecycle cost of

the machines (e.g. investment cost and oper-

ating cost during lifetime) taking into account

energy cost so as to compare investments. If

replacement has already been prescribed, it

is recommended to take the highest energy-

efficiency class.

10.2.2 Efficiency Pumps and Pump Control

Older pumps often have a lower efficiency

than a new pump, but the construction age is

not necessarily an indication for this problem.

Old pumps can also have efficiency compa-

rable to new pumps. Therefore, it is advisable

to look at these pumps in more detail with the

focus on the following questions:

• Does the pump operate in the range of its dimensioning? (amount of water, manometric head etc.)

• Does the efficiency correspond to the manufacturer’s information?

• How great is the attrition? • How often will the pump be main-

tained? • How often will the pump be cleaned?

Each pump should be checked with regard to

its power consumption, operation with other

pumps and range of its dimensioning. If the

efficiency of the pump compared to a new

pump is lower, there are two possible actions:

Figure 9: Specification of energy efficiency according to the IEC 60034-30 [10]

86.00 %87.00 %88.00 %89.00 %90.00 %91.00 %92.00 %93.00 %94.00 %95.00 %96.00 %97.00 %98.00 %

0 kW 50 kW 100 kW 150 kW 200 kW 250 kW 300 kW 350 kW 400 kW

IE3: 2-pole IE3: 4-pole IE3: 6-pole IE2: 2-pole IE2: 4-pole

IE2: 6-pole IE1: 2-pole IE1: 4-pole IE1: 6-pole


Page 34

• adjustment of the operation (compara-tive moderation of hydraulic loads)

• replacement of the pump

If replacement of the pump is the only option,

it is necessary to take a pump with a hi gh

specified energy efficiency class according to

the international standard IEC 60034-30.

Furthermore, it is very important to consider

the NPSH (net positive suction head). The

NPSH is relevant inside centrifugal pumps

and turbines in systems that are most vulner-

able to cavitation. If cavitation occurs the co-

efficient of performance will increase drasti-

cally and could damage the impeller. To pre-

vent cavitation, the pressure in front of the

impeller has to be above the vapor pressure

of the pumped medium.

The use of multiple pumps with the same or

different capacity or a frequency control can

be a good way of controlling a high variation

in the water amount.

The decision whether multiple pumps or a

frequency control should be used, can only

be determined by a detailed analysis. For this

purpose, the load profile should be examined

by means of simulations or measurements.

The energy saving potential with the frequen-

cy control can be 35 % of the energy con-

sumption depending of the pump characteris-

tics and the demand fluctuation. The power

loss through the use of a frequency control is

up to 5 %.

10.2.3 Aeration of Activated Sludge

In a typical wastewater treatment plant

(WWTP) with an ac tivated sludge process,

the largest energy usage comes from the

aeration of the activated sludge.

A common form of the aeration is subsurface

aeration. In this process a blower support the

diffusers, which placed on the bottom, with air

through a piping system. To achieve a sys-

tem with good energy efficiency, it is im-

portant that the equipment is well sized and

configured. Also the motor of the blower has

to be a high energy efficiency class. So there

are four basic aspects to achieve energy effi-

ciency in aeration:

• blower • piping system • diffusers • aeration control

To improve the energy efficiency of positive

displacement blowers, variable frequency

drive can be used. This makes it possible to

run the blower efficiently for different loads.

The piping system has to be w ell sized to

make sure that the flow speed is not too high

and the pressure loss is minimized.

The diffuser releases the air to the waste wa-

ter and can be categorized into two main dif-

fuser types: coarse bubble and fine bubble

diffusers. Because the oxygen transfer is bet-

ter with fine bubbles, the need of air is much

lower and energy can be saved.


Page 35

One common aeration control strategy is dis-

solved oxygen control, which aims at keeping

a constant solved oxygen level in the tank.

Another control strategy is ammonium con-

trol, which is used around the solve oxygen

control and gives a bet ter possibility to con-

trol. This can save energy.

10.2.4 Efficiency Mixer with CFD Sim-ulation Software

The efficiency of the mixer depends on sev-

eral aspects such as the volume of the tank,

the aeration, the type of the stirrer, the solid

content and the inflow. The DWA-A 216 gives

theoretical values for an opt imized power

input in the tank:

• < 2,000 m³ 1.5 W/m³ • 1,000 m³ <> 2,000 m³ 2 to 1.5 W/m³ • 500 m³ <> 1,000 m³ 2 to 2.5 W/m³ • 200 m³ <> 500 m³ 2.5 to 4 W/m³

These values establish evidence as to how

big the rated power capacity of the stirrer

should be, but have to be examined with the

aspects described above. A recommended

method to gather a l ot of information about

the mixing situation is the use of Computa-

tional Fluid Dynamics (CFD).

This powerful tool is invaluable within all dis-

ciplines of fluid dynamics and mixing know-

how. The method enables masses of data

and integrated parameters which can be use-

ful in the planning stage of a project involving

mixing design.

The simulation software enables a look at the

mixing situation and r eveals problems. The

replacement of an old inefficient mixer or the

replacement of several mixers with only one

could be an action with a high energy saving

potential.

Figure 10: Example for a CFD simulation

10.2.5 Hydropower Turbine

There are two types of hydropower turbines:

impulse and r eaction. What type is selected

for a water supply facility and the best place

to install the turbine is based on the following

aspects:

head pressure

What is the water pressure at the turbine in-

let? What pressure is needed at the turbine

outlet? This is important because the availa-

ble pressure for power production is the dif-

ference between the turbine inlet and outlet.


Page 36

flow duration

What amount of water is transported through

the pipes? Is the flow rarely constant?

pipeline length and diameter

The length and diameter is important for cal-

culating friction losses within the pipeline at

varying flows.

electrical requirements

What output voltage and frequency are re-

quired from the generator?

The impulse turbine uses the velocity of the

water transported and moves the runner. The

turbine has several buckets on t he runner

and the water stream hits the bucket. An im-

pulse turbine is generally suitable for high

head and low flow applications.

Figure 11: Impulse hydropower turbine

The reaction turbine with blades combines

the pressure of the water and t he water

stream. The runner is placed directly in the

water stream and the water stream flows over

the blades rather than striking each individu-

ally. Reaction turbines can be used for lower

head and higher flows corresponding to the

requirements of the water supply.

Figure 12: Reaction hydropower turbine

Hydropower turbines can be pl aced in the

inlet of the water storage or between two

pressure zones. They also can be us ed to

perform the function of pressure reduction.

Not all water supply systems are suitable for

a hydropower turbine. It is necessary to keep

the first priority the delivery of water and not

the use of hydropower. Some of the pipelines

were never designed to withstand the pres-

sure which forms when a hydropower turbine

is installed and the turbine is taken out of

operation. Especially old and long pipes have

these problems, so a good time to evaluate

the feasibility of a hydropower turbine is gen-

erally when an aging pipeline is replaced.

10.2.6 Solar Thermal Systems in De-salination

Solar thermal systems can be di vided into

concentrating and non -concentrating solar

thermal. The differences exist in the collection

of solar radiation and the temperatures. For

the non-concentrating solar thermal energy,

the sun's rays are absorbed by closed collec-


Page 37

tors with a heat transfer medium. This heat,

normally 80 ° C, can be used for heating of

buildings and water heating, but it is too cold

to use as process heat. The concentrating

solar thermal system reflects the sun's rays to

a point and can reach higher temperatures,

normally between 200 ° C and 500 ° C. The

overall efficiency of such facilities is on aver-

age approximately 50 %.

Figure 13: Solar thermal systems

The heating of buildings or water heating is

not a big issue in the MENA water sector, but

the desalination facilities often have a high

heat requirement for heating the water to boil-

ing temperature. The future costs will contin-

ue to depend on the price of the energy and

desalination technology used.

With solar thermal systems, part of this heat

can be pr ovided from the sun. The solar

thermal system should be c onfigured with

heat-storage to ensure a r egular supply of

heat. Furthermore, the facilities must be

equipped with normal technology to produce

heat during long periods without low sunlight.

What kind of solar thermal system is best,

what dimensions are required for the systems

and how big the heat storage has to be de-

pends on the desalination technique, the heat

demand and the water storage.

10.2.7 Photovoltaics

Photovoltaic (PV) modules generate electrical

power by converting solar radiation using the

photovoltaic effect. The photovoltaic modules

contain a num ber of solar cells which are

most commonly made of silicon. The conver-

sion to electrical power occurs without any

moving parts and i t is pollution-free during

operation.

The rated power capacity range can be real-

ized from a few milliwatts to megawatts sys-

tems and has the benefit that the systems

can be expanded in every planning stadium.

The performance is given in kW peak [kWP]

and describes the rated output under test

conditions and the maximum solar radiation.

For better performance, the PV systems aim

to increase the time they face the sun. With

solar trackers it is possible to achieve this by

moving the system panels to follow the sun

(Figure 14). That increases the energy pro-

duction by up to 20 % in winter and up to

50 % in summer.


Page 38

Figure 14: Solar systems

A further advantage of PV is that they only

need little maintenance – it is only necessary

to keep the panels clean and make sure that

trees or other objects don't begin to over-

shadow them.

The quantity of annual sunlight in the MENA

water sector creates an awesome solar po-

tential. Depending on the region, the annual

total direct normal irradiation varies from

1,500 to 3,000 kWh / (m² · a). That is a bi g

difference to Germany where, in comparison

the potential ranges from 1,100 to

1,500 kWh / (m² · a). The solar system can

be integrated in the waste water treatment

plant or water supply facilities when building

on free areas or beyond the facilities’ board-

er.

10.2.8 Cooling with Heat

Cooling accounts for a large percentage of

the energy consumption in the MENA water

sector. Most of the energy used for cooling is

consumed by the air conditioning of the build-

ings. The conventional cooling systems in

waste water treatment facilities or water sup-

ply facilities use a compressor, which is usu-

ally electrically driven and has a high power

consumption.

The utilisation of an a bsorption refrigerator

can be an oppor tunity to cool the building

using heat from the biogas applied in waste

water treatment plants. Furthermore, the ab-

sorption refrigerator can also use other heat

sources like solar or waste water heat to pro-

vide the energy needed in the cooling sys-

tems.

The absorption refrigerators use a refrigerant

with a very low boiling point. The heat re-

quired to boil this refrigerant comes from the

surrounding area and provides the cooling.

The cooling cycle can be restarted, when the

boiled refrigerant is cooled down to liquid,

which is the difference between the conven-

tional cooling system and the absorption re-

frigerators. The conventional cooling system

uses a compressor to compress the refriger-

ant. With a hi gher pressure the temperature

required to evaporate a liquid decreases and

the refrigerant can be condensed again. The

absorption refrigerators use other liquids or

salt which absorb the boiled refrigerant. To

evaporate and c ondense the refrigerant out

of the loaded liquid, the liquid is heated by

other heat sources such as solar energy,

CHP or waste water heat. Thus, the cooling

cycle can be described in three steps:

Evaporation

The liquid refrigerant evaporates in a low par-

tial pressure area by taking heat from the

surrounding area.


Page 39

Absorption

The gaseous refrigerant is absorbed by a salt

or liquid.

Regeneration

The loaded liquid is heated by other heat

sources and the refrigerant evaporates and

condenses out.

10.2.9 Electrical Load Management

Electrical load management is the process of

balancing the supply of electricity to the facili-

ty with the electrical load by adjusting the

current power or the operational time of ma-

chines. The goal is an improvement of valua-

ble resources from reduced total system peak

load. It serves the efficient use of investments

related to production and distribution of elec-

tricity and avoids the requirement to increase

transformer, cable sizes and g enerator ca-

pacity.

Normally the energy used will vary throughout

the day, depending upon factors such as the

water demand or the biological oxygen de-

mand loading for waste water plants. Some of

the machines have to run during the daily

electric consumption peak. But many loads

and machines can be scheduled for off peak-

operation. For example, facilities can use the

system to storage, operating of dewatering,

filtration back-washing in the night or avoiding

running large intermittent pumps when oper-

ating the main pumps.

As a further example, it is possible to save

energy in such electrical load management

with optimized water storage. The main focus

should be on the use of the total water stor-

age volume, so a comparative moderation of

hydraulic loads is possible.

At night when the water demand is not so

high, the pumps could use the time to fill the

water container. Therefore, the pumps can

operate more efficiently and in case of tempo-

rarily lower water demand the velocity of the

water stream is lower and t he pressure loss

decreases.

A management strategy should be deter-

mined individually for each container, based

on the evaluation of the daily hydraulic loads.

10.2.10 Anaerobic Sludge Treatment

Anaerobic digestion in contrast to the aerobic

sludge treatment is a process by which mi-

croorganisms break down biodegradable ma-

terial in the sludge in the absence of oxygen.

Anaerobic digestion is a well-established

treatment technology suited to treat sludge in

waste water treatment plants. It is a l ow en-

ergy process which generates biogas. This

biogas can be us ed in CHP to increase the

facility’s own energy production.

The main advantage of anaerobic treatment

is that it has lower operating costs as a result

of the low energy inputs. But it also decreas-

es considerably the quantity of sludge for

disposal and it allows reducing the necessary

volume of aeration tanks. This may allow in-

creasing considerably the capacity of a

WWTP.


Page 40

11 Bibliography

[1] DWA, DWA-A 216: Energy check and

energy analysis – tools for energy

optimization of waste water plants, 2013.

[2] DVGW and G erman Federal

Environmental Foundation, Guideline

energy efficiency and energy saving in

water supply, 2010.

[3] M. f. C. P. -. E. -. A. -. N. C. a. C. P. o. t.

G. S. o. N. Rhine-Westphalia, Energy on

Waste Water Treatment Plants, 1999.

[4] P. Baumann und M . Roth, Reduction of

electric consumption for waste water

treatment plants, Stuttgart: DWA, 2014.

[5] I. 50001, Energy management sys-tems -

Requirements with guidance for use.

[6] D. E. 16247-1, Energy audits - Part 1:

General requirements.

[7] ACWUA, ACWUA Wiki,

http://www.acwua.org/.

[8] GUTcert Certifizierungsgesellschaft,

Guideline to Efficient Energy

Management according to ISO 50001 /

Guide pour un management efficace de

l'énergie selon ISO 50001, Version 4.2

(EN/FR/GER and other languages),

Berlin, 2014.

[9] G. F. M. f. t . E. -. N. C. a. N. Safety,

Energy Management Systems in Practice

- ISO 50001: A Guide for Companies and

Organisations, 2012.

[10] E. J. D. P. H. S. T.-F. H. Cabrera,

Benchmarking Water Service - Guiding

water utilities to excellence, London:

IWA-Publishing, 2011.

[11] I. 60034-30, Rotating electrical machines

- Part 30: Efficiency classes of

singlespeed, three-phase, cage-induction

motors, 2012.

[12] VSA/suisse énergie, Guide de

l'optimisation énergétique des stations

d'épuration des eaux usées, 2008/2010.


APPENDIX

Operation Plan Energy Check .................................................................................................... 43

Operation Plan Energy Analysis ................................................................................................ 45

Key Performance Indicators of Energy Analysis ...................................................................... 47

Water Supply Data Variables (Variables ws) ................................................................................. 49

Water supply energy check key performance indicators ................................................................ 60

Waste Water Disposal Data Variables (Variables wd) ................................................................... 70

Waste Water Disposal Energy Check Key Performance Indicators ............................................... 85

DWA-A 216 Frequency Distributions ......................................................................................... 96

Example List of Machines ......................................................................................................... 100

Energy Analysis Calculation of the Theoretical Values .......................................................... 101

Water Supply ............................................................................................................................. 101

Waste Water Disposal ................................................................................................................. 103


Page 2

Operating Plan Energy Check

Page 43

Operation Plan Energy Check (Chapter 6 and 7)

Administrative preparation

Chapter 6.1

energy policy

energy goals

area focus

assessment

period

energy sources

Study Parameter

Chapter 6.2

Data collection

Chapter 7

Water Supply

• water quantity in water abstraction [m³/a]


• total power consumption of the pure water pumping station per year [kWh/a]

• total power consumption of every other pumping station per year [kWh/a]

• energy production of com-bined heat and power (CHP) per year [kWh/a]

• total energy production from other energy sources per year [kWh/a]


• total number of inhabitants and population equivalents [PT]


• total power consumption of the aeration per year [kWh/a]

• energy production of com-bined heat and power (CHP) per year [kWh/a]

• total energy production from other energy sources per year[kWh/a]

• total power consumption of every other pumping station per year [kWh/a]

• water flows • water quality • water losses • waste water load • biogas produc-

tion • etc.

Data Validation

Chapter 6.3

• check the current

conditions • take meter readings • determine optional

measurement cam-paign for collecting additional data

• inspect and verify equipment infor-mation

• take photo docu-mentation

• review the materials collected

• and interview opera-tors

Facility Inspection

Chapter 6.4

KPIs

Chapter 7.1

Water Supply

1. specific power consumption per facility [kWh/(m³ · a)]

2. specific power consumption pure water pumping station [kWh/(m³ · a)]

3. specific power consumption of every other pumping sta-tion [kWh/(m³ · a)]

4. level of self-supply electricity [%]


1. specific power consumption per facility [kWh/(PT · a)]

2. specific power consumption aeration [kWh/(PT · a)]

3. level of self-supply electricity [%]

4. specific power consumption of pumping stations [kWh/(m³ · a)]

Energy Mapping

Chapter 7.2

determine areas with a

higher need of energy

efficiency and focus

them during the Energy

Analysis

First Orientation for Water Supply and Waste Water Dis-

posal

statistical frequency distribution

If possible: First Actions Monitoring

Energy Analysis Chapter 8

Operating Plan Energy Check

Operating Plan Energy Analysis

Page 45

Operation Plan Energy Analysis (Chapter 6 and 8) Page 1

Administrative preparation

Chapter 6.1

energy policy

energy goals

area focus

assessment

period

energy sources

Study Parameter

Chapter 6.2

Data collection

Chapter 8

Water Supply and Waste Water

Disposal

general information

• name, address and operator of the facility

• contact person for energy • details of the facility such as

technique, water parameters, population in total, etc.

• energy supply contracts process information

• design report • technical documentation • procedural schemes • piping and instrumentation

diagram • operating manual operating data

• water abstraction (only water supply)

• water transmission • water treatment • waste water treatment (only

waste wa-ter disposal) • sludge treatment (digester,

dewatering etc.) • external substrate intake (co-

digestion) (only waste water disposal)

• biogas (only waste water dis-posal)

• energy and material con-sumption

• HVAC systems (heating, ven-tilation and air conditioning)

List of machines

• type • year of construction • operating hours • rated power capacity, cos φ,

V, I and/or power consump-tion

• information about frequency conversion

• water flows • water quality • water losses • waste water load • biogas produc-

tion • etc.

Data Validation

Chapter 6.3

• check the current

conditions • take meter readings, • determine optional

measurement cam-paign for collecting additional data

• inspect and verify equipment infor-mation

• take photo docu-mentation

• review the materials collected

• and interview opera-tors

Facility Inspection

Chapter 6.4

search for external

experts

Further KPIs

Chapter 8 / Appendix Page 2

Operating Plan Energy Analysis

Page 46

Operation Plan Energy Analysis (Chapter 6 and 8) Page 2

Measurement

• counter • measure the actual am-

perage • simplified calculation • variable

speed/frequency

Energy Balance

Chapter 8.1

Consumption Matrix

• type • year of construction • operating hours • rated power capacity,

cos φ, V, I and/or power consumption

• information about fre-quency conversion

• pie charts

Page 1

Questions

• what machines are in my facility? Look at the list of machines and the pie chart?

• which theoretical values can I use for my facility?

• what are the specific units? • what data do I need to calculate

the theoretical values?

Evaluation of the Energy Balance

Chapter 8.2

Theoretical Values

• calculations in the appendix • comparison with the Energy Bal-

ance • identify the deviations

Actions

Reduction of Energy Consumption

• reduce the energy demand • increase the energy efficiency • improve the power factor

Optimization of Energy Supply

• purchase electricity, heat and fuel cheaper

• increase one’s own energy produc-tion /energy recovery

Establishment of Actions

Chapter 8.3

Monitoring

Economic Efficiency Analysis of the Actions

Prioritisation of the Actions

• direct Actions • short-Term Actions • long-Term Actions

Definition of an Action-Plan

Realisation of the Action-Plan

Key Performance Indicators of Energy Analysis

Page 47


Water Supply

total energy recovered / total pumping energy consumption x 100

wsEp2 – total energy production other than recovery (%)

total energy recovered / total energy consumption for water supply division x 100

wsMc1 – electrical energy cost (Dollar/kWh)

total energy costs / total energy consumption for water supply division

wsEc7a – energy consumption main pumps (kWh/m³)

energy consumption drinking water main pumps / drinking water production volume

wsEc8a – energy consumption booster pumps (kWh/m³)

energy consumption drinking water booster pumps / pressure boosted drinking water volume

wsEp1 – total energy recovery (%)

energy consumption well pump, intake pump / abstraction volume

wsEc4a – energy consumption raw water booster pumps (kWh/m³)

energy consumption raw water booster pumps / pressure boosted raw water volume

wsEc5a – overall plant energy consumption per produced volume (kWh/m³)

wsEc6 – heat demand per volume produced (kWh/m³)

wsEc4 – standardised energy consumption raw water booster pumps (kWh/m³/100m)energy consumption raw water booster pumps / pressure boosted raw water volume / pump head raw water booster pumps x 100

wsEc5 – overall plant energy consumption per intake volume (kWh/m³)

overall waterworks facility energy consumption / treatment input volume

wsEc1 – energy content per authorised consumption (kWh/m³)

overall waterworks facility energy consumption / drinking water production volume

total energy consumption for water supply division / authorised consumption

wsEc2 – proportion of pumping energy (%)

total pumping energy consumption / total energy consumption for water supply division x 100

wsEc3 – standardised energy consumption abstraction / intake pumps (kWh/m³/100m)energy consumption well pump, intake pump / abstraction volume / pump head well pump, intake pump x 100

wsEc8 – standardised energy consumption booster pumps (kWh/m³/100 m)energy consumption drinking water booster pumps / pressure boosted drinking water volume / pump head drinking water booster pumps x 100

wsEc3a – energy consumption abstraction / intake pumps (kWh/m³)

energy consumption water treatment / drinking water production volume

wsEc7 – standardised energy consumption main pumps (kWh/m³/100 m)energy consumption drinking water main pumps / drinking water production volume / pump head drinking water main pumps x 100


Page 48


energy consumption lifting pumps in sewer system / lifted volume

wdEc3a – overall plant energy consumption per volume of wastewater treated (kWh/m³)

overall wastewater treatment plant energy consumption / volume of wastewater treated

wdEc4a –energy consumption pumps water treatment (kWh/m³)

energy consumption water pumps on wastewater treatment plants / wastewater volume elevated

wdEc7 –energy consumption sludge pumping (kWh/m³)

energy consumption sludge pumps on wastewater treatment plants / sludge volume elevated

wdEc9 –energy consumption tertiary treatment (kWh/m³)

energy consumption tertiary treatment stage / wastewater receiving tertiary treatment

wdEp1 – total energy recovery from biogas (%)

total energy recovered / total energy consumption for waste water disposal division x 100

wdEp2 – total energy production other than from biogas (%)

wdEp3 –biogas generation per population equivalent (kWh/p.e.)

volume of biogas production / population equivalents served

wdEp4 – proportion of biogas conversion into energy (%)

electric energy production by cogeneration / energy content of biogas production x 100

total energy produced other than from biogas / total energy consumption for wastewater disposal division x 100

wdEc1 –energy consumption per population equivalent served (kWh/p.e.)

total energy consumption for wastewater disposal / total population equivalents

wdEc2– standardised energy consumption lifting pumps in sewer system (kWh/m³/100 m)

energy consumption lifting pumps in sewer system / lifted volume / pump head lifting pumps x 100

wdEc8 – heat demand per population equivalent served (kWh/p.e.)

heat demand / population equivalents served

wdEc1a – energy consumption per wastewater volume disposed (kWh/m³)

total energy consumption for wastewater disposal / total volume of wastewater treated

wdEc2a – energy consumption lifting pumps in sewer system (kWh/m³)

wdEc5 – energy consumption biological aeration (kWh/p.e.)

energy consumption aeration component / population equivalents served

wdEc6 – energy consumption sludge treatment (kWh/ton DS)

energy consumption sludge treatment / sludge volume handled

wdEc3 – overall plant energy consumption per population equivalent served (kWh/p.e.)

overall wastewater treatment plant energy consumption / population equivalents

wdEc4 – standardised energy consumption pumps water treatment (kWh/m³/100 m)

energy consumption water pumps on wastewater treatment plants / wastewater volume elevated / pum


Page 49

Water Supply Data Variables (Variables ws)

Data variables addressing monetary cost of energy (variables wsM)

wsM1 – total energy costs (Dollar)

Costs of electrical energy (including energy for pumping and all other activities related to water supply, e.g. energy for water treatment, premises, offices etc.) during the as-sessment period.

INPUT DATA

Referred to a reference period

Referred to utility level

This variable includes not only the costs proportional to energy consumption but also all the

other costs associated with energy purchases such as power tariffs and taxes. Data is to be

derived from the financial statement of the undertaking. Exchange rates of local currencies

should be referred to at the end of the assessment period.

Used for indicator(s): wsMc1

Data variables addressing energy consumption (variables wsC)

wsC1 – total energy consumption for water supply division (kWh)

Electrical energy consumption (including energy for pumping and all other activities related to water supply, e.g. energy for water treatment, premises, offices etc.) during the assessment period.

INPUT DATA



This variable is the total energy consumption of the water supply division or undertaking. If

there is no energy production data is to be derived from the bills of the energy supplier. If con-

sumption is derived from bills of the energy supplier, self produced and consumed energy has

to be added.

Used for indicator(s): wsEc1, wsEp2


Page 50

wsC2 – total pumping energy consumption (kWh)

Electrical energy consumption for water pumping (customer pumping systems exclud-ed) during the assessment period.

INPUT DATA



This variable is the total energy consumption of every water-pumping component of the water

supply division or undertaking. Data is to be derived from energy consumption meters or from

the bills of the energy supplier. The consumption of small pumps may be excluded if their influ-

ence in terms of the global confidence grade of the variable is negligible.

Used for indicator(s): wsEc2, wsEp1

wsC3 – energy consumption well pump, intake pump (kWh)

Electrical energy consumption for each pumping component of the catchment area dur-ing the assessment period.

INPUT DATA


Referred to component level

The data variable is to be assessed for each and every pumping component in the catchment

area. Data is to be de rived from energy consumption meters or from the bills of the energy

supplier. If the consumption is not shown on a separate bill and no meter is installed, it needs

to be measured for all relevant operating states of the component on-site. Measured data may

be projected for the whole period. If this procedure is too time consuming, for non-power-

controlled pumps it may be r easonably estimated by multiplying pump nominal power with

pump working hours during the assessment period.

Used for indicator(s): wsEc3, wsEc3a


Page 51

wsC4– energy consumption raw water booster pumps (kWh)

Electrical energy consumption for each pumping component of the raw water transmis-sion system during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every pumping component in the raw water

transmission system. Data is to be derived from energy consumption meters or from the bills of

the energy supplier. If the consumption is not shown on a s eparate bill and no m eter is in-

stalled, it needs to be measured for all relevant operating states of the component on-site.

Measured data may be projected for the whole period. If this procedure is too time consuming,

for non-power-controlled pumps it may be reasonable estimated by multiplying pump nominal

power with pump working hours during the assessment period.


wsC5– overall waterworks facility energy consumption (kWh)

Electrical energy consumption of the entire treatment process in the waterworks facility.

INPUT DATA


Referred to plant level

The data variable is to be assessed for each and every waterworks facility of the undertaking.

For classic treatment, the variable corresponds to the energy consumption of the low voltage

busbar of the waterworks facility. Data is to be derived from energy consumption meters or

from the bills of the energy supplier.



Page 52

wsC6– heat demand (kWh)

Thermal energy demand by evaporators in desalination plants using either multistage flash evaporation (MSF) or multiple effect distillation (MED) process engineering.

INPUT DATA


Referred to process level

The variable should be assessed for each and every desalination plant of the undertaking. The

variable corresponds to the heat energy that has been produced in order to be utilised within

which the desalination process.

Used for indicator(s): wsEc6

wsC7– energy consumption drinking water main pumps (kWh)

Electrical energy consumption for each pumping component on-site at the waterworks facility feeding the water transmission system during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every pumping component feeding the water

transmission system on-site at each and every waterworks facility. Data is to be derived from

energy consumption meters or from the bills of the energy supplier. If the consumption is not

shown on a separate bill and no meter is installed, it needs to be measured for all relevant op-

erating states of the component on-site. Measured data may be projected for the whole period.

If this procedure is too time consuming, for non-power-controlled pumps it may be reasonable

estimated by multiplying pump nominal power with pump working hours during the assessment

period.



Page 53

wsC8– energy consumption drinking water booster pumps (kWh)

Electrical energy consumption for each pumping component in the water transmission and distribution system during the assessment period.

INPUT DATA



The data variable is to be assessed for each and ev ery pumping component in the water

transmission and distribution system. Data is to be derived from energy consumption meters or

from the bills of the energy supplier. If the consumption is not shown on a separate bill and no

meter is installed, it needs to be measured for all relevant operating states of the component

on-site. Measured data may be projected for the whole period. If this procedure is too time con-

suming, for non-power-controlled pumps it may be reasonably estimated by multiplying pump

nominal power with pump working hours during the assessment period. If in a particular case a

fuel driven pump is to be assessed, the amount of diesel needs to be converted to power using

its specific heating value.


Data variables addressing energy production (variables wsP)

wsP1 – total energy recovered (kWh)

Total electrical energy recovered by the use of turbines or reverse pumps in the entire water supply system that is operated by the undertaking during the assessment period.

INPUT DATA



The data variable is to be assessed for the entire water supply system operated by the under-

taking. Energy recovery relates to the amount of energy produced by the undertaking by utilis-

ing potential energy surpluses for hydraulic transport needs in order to cover parts of its energy

demand for water supply.

Used for indicator(s): wsEp1


Page 54

wsP2 – total energy produced other than recovered (kWh)

Total electrical energy produced by means of e.g. photovoltaic, wind turbines at the premises of the entire water supply division of the undertaking during the assessment period.

INPUT DATA



The data variable is to be assessed for the entire water supply division of the undertaking. En-

ergy production relates to the amount of energy produced from renewable sources on-site on

the entire premises of the water supply division/undertaking in order to cover parts of its energy

demand for water supply. Energy production by utilising potential energy surpluses for hydrau-

lic transport needs only needs to be i ncluded if the volume used for hydropower generation

was not first elevated by pumps operated by the undertaking (e.g. if the water resource is situ-

ated at a r elatively high altitude in an impounding reservoir). In all other cases, hydropower

generation is to be assessed using data variable wsP1.

Used for indicator(s): wsEp2

Data variables addressing water volumes (variables wsW)

wsW1 – authorised consumption (m³)

Total volume of water that is taken by registered customers, other authorised parties (e.g. fire fighters, municipalities for watering, street cleaning etc.) or by the water suppli-er itself.

INPUT DATA



The data variable is to be assessed for the entire water supply division of the undertaking. Au-

thorised consumption may be metered or unmetered as well as billed or unbilled. It is recom-

mended to use IWA standard water balance to calculate authorised consumption.

Used for indicator(s): wsEc1,


Page 55

wsW2 – abstraction volume (m³)

Volume of water that was abstracted from raw water resources for each pumping com-ponent in the catchment area during the assessment period.

INPUT DATA




area. Data can be derived by reading installed flow meters. If there is no flow meter installed or

no record available, it needs to be estimated by the best means available.


wsW3– pressure boosted raw water volume (m³)

Volume of raw water pressurised by each pumping component in the raw water trans-mission system during the assessment period.

INPUT DATA




transmission system. Data can be derived by reading installed flow meters. If there is no flow

meter installed or no record available, it needs to be estimated by the best means available.



Page 56

wsW4 – treatment input volume (m³)

Volume of raw water input to each waterworks facility during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every waterworks facility of the undertaking. It

includes both the volume of raw water abstracted from own resources and imported raw water

but less raw water losses due to leakage, inaccuracies associated with metering and raw water

taken by the water supplier for own uses and export. The volume should be metered at the inlet

valve. If the treatment input volume is unmetered, data variable wsW4 should be used as an

alternative.


wsW5– drinking water production volume (m³)

Volume of water treated for input to the water transmission lines of each waterworks facility during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every waterworks facility of the undertaking.

The volume should be metered at the outlet valve. It corresponds to the treatment input volume

less treatment operational consumption.

Used for indicator(s): wsEc5a, wsEc6, wsEc7, wsEc7a


Page 57

wsW6– pressure boosted drinking water volume (m³)

Volume of drinking water pressurised by each pumping component in the water trans-mission and distribution system during the assessment period.

INPUT DATA




transmission and distribution system. Data can be derived by reading installed flow meters. If

there is no flow meter installed or no record available, it needs to be estimated by the best

means available.


Data variables addressing pump heads (variables wsH)

wsH1 – pump head well pump, intake pump (m)

Pump head for each pumping component in the catchment area during the assessment period.

INPUT DATA




area. For pumps with significant variation of the pump head throughout the assessment period,

the period should be subdivided into a limited number of time intervals. For instance, if a pump

works 1/3 of the time with a flow Q1 = 10 m³/h and a pump head of h1 = 50 m, and 2/3 of the

time with a flow Q2 = 12 m³/h and a pump head h2 = 42 m, the resulting pump head will be:

( (1/3) x Q1 x h1 + (2/3) x Q2 x h2 ) / ( (1/3) x Q1 + (2/3) x Q2 ) = 44.35 m



Page 58

wsH2 – pump head raw water booster pumps (m)

Pump head for each pumping component in the raw water transmission system during the assessment period.

INPUT DATA




transmission system. For pumps with significant variation of the pump head throughout the

assessment period, the period should be subdivided into a limited number of time intervals. For

instance, if a pump works 1/3 of the time with a flow Q1 = 10 m³/h and a pump head of h1 = 50

m, and 2/3 of the time with a flow Q2 = 12 m³/h and a pump head h2 = 42 m, the resulting pump

head will be:

( (1/3) x Q1 x h1 + (2/3) x Q2 x h2 ) / ( (1/3) x Q1 + (2/3) x Q2 ) = 44.35 m


wsH3 – pump head drinking water main pumps (m)

Pump head for each pumping component on-site of the waterworks facility feeding the water transmission system during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every pumping component feeding the water

transmission system on-site of each and every waterworks facility. For pumps with significant

variation of the pump head throughout the assessment period, the period should be subdivided

into a limited number of time intervals. For instance, if a pump works 1/3 of the time with a flow

Q1 = 10 m³/h and a pump head of h1 = 50 m, and 2/3 of the time with a flow Q2 = 12 m³/h and a

pump head h2 = 42 m, the resulting pump head will be: ( (1/3) x Q1 x h1 + (2/3) x Q2 x h2 ) / (

(1/3) x Q1 + (2/3) x Q2 ) = 44.35 m



Page 59

wsH4 – pump head drinking water booster pumps (m)

Pump head for each pumping component in the water transmission and distribution sys-tem during the assessment period.

INPUT DATA




transmission and di stribution system. For pumps with significant variation of the pump head

throughout the assessment period, the period should be subdivided into a l imited number of

time intervals. For instance, if a pump works 1/3 of the time with a flow Q1 = 10 m³/h and a

pump head of h1 = 50 m, and 2/3 of the time with a flow Q2 = 12 m³/h and a pump head h2 = 42

m, the resulting pump head will be: ( (1/3) x Q1 x h1 + (2/3) x Q2 x h2 ) / ( (1/3) x Q1 + (2/3) x Q2

) = 44.35 m



Page 60

Water supply energy check key performance indicators

Performance indicators addressing energy consumption (indicators wsEc)

wsEc1 – energy content per authorised consumption (kWh/m³)

total energy consumption for water supply division / authorised consumption

wsEc1 = wsC1 / wsW1


wsW1 – authorised consumption (m³)

This indicator provides a measure of the necessary energy utilisation by the undertaking per m³

of authorised potable water during the assessment period and is equal to its total electrical en-

ergy content. It can be used as a measure of how well energy efficiency improvement efforts

are globally evolving.

Main explanatory factors for external comparison:

• Energy conversion efficiency of the pumps

• Utilised process engineering for water treatment

• Geomorphology of the supply area

• Difference between elevation of water resources and maximum, minimum delivery ele-

vation

• Reactive energy consumption

Usual values are between 0.2 and 1.2 kWh/m³ provided the undertaking does not operate a

desalination plant.


Page 61

wsEc2 – proportion of pumping energy (%)

total pumping energy consumption / total energy consumption for water supply division x 100

wsEc2 = wsC2 / wsC1 x 100



This indicator provides a measure of the proportion of energy used for water pumping. It can be

used to monitor whether pumping energy conversion efficiency improvements are eroded by

increasing consumption deterioration of other energy consumers.

Usually the proportion of pumping energy is above 80% of the total energy consumption. How-

ever, the proportion depends largely on t he consumption of utilised process engineering for

water treatment.

wsEc3 – standardised energy consumption abstraction/intake pumps (kWh/m³/100m)

energy consumption well pump, intake pump / abstraction volume / pump head well pump, intake pump x 100

wsEc3 = wsC3 / wsW2 / wsH1 x 100



wsH1 – pump head well pump, intake pump (m)

This indicator provides a measure of the energy conversion efficiency of the well or intake

pumps operated by the undertaking. It equals the average amount of energy consumed per m³

at a pum p head o f 100 m. It is the inverse of the pumping efficiency. A value of 0.5

kWh/m³/100m for this indicator corresponds to an average pumping efficiency of 9810 N x 100

m / (3600 J/Wh) / 500 Wh x 100 = 55%. Usual values for well pumps are between 25% and

60%.


Page 62

wsEc3a – energy consumption abstraction/intake pumps (kWh/m³)

alte

rnat

ive

indi

cato

r

energy consumption well pump, intake pump / abstraction volume

wsEc3a = wsC3 / wsW2



This indicator provides a measure of energy utilisation of the well or intake pumps oper-

ated by the undertaking in relation to the volume elevated during the assessment period.

As this indicator does not consider pump head, it should be only used if indicator wsEc3

cannot be calculated.

wsEc4 – standardised energy consumption raw water booster pumps (kWh/m³/100m)

energy consumption raw water booster pumps / pressure boosted raw water volume / pump head raw water booster pumps x 100




wsH2 – pump head raw water booster pumps (m)

This indicator provides a measure of the energy conversion efficiency of the raw water booster

pumps operated by the undertaking. It equals the average amount of energy consumed per m³

at a pum p head o f 100 m. It is the inverse of the pumping efficiency. A value of 0.5


m / (3600 J/Wh) / 500 Wh x 100 = 55%. Usual values for (drinking water) booster pumps are

between 50% and 70%.


Page 63

wsEc4a – energy consumption raw water booster pumps (kWh/m³) al

tern

ativ

e in

dica

tor

energy consumption raw water booster pumps / pressure boosted raw water vol-ume




This indicator provides a measure of energy utilisation of the raw water booster pumps

operated by the undertaking in relation to the pressure boosted raw water volume during

the assessment period. As this indicator does not consider pump head, it should be only

used if indicator wsEc4 cannot be calculated.


Page 64

wsEc5 – overall plant energy consumption per intake volume (kWh/m³)

overall waterworks facility energy consumption / treatment input volume

wsEc5 = wsC5 / wsW4


wsW4 – treatment input volume (m³)

This indicator provides a measure of energy utilisation by the treatment process in relation to

the raw water plant intake volume during the assessment period.

In some cases, raw water will have an energy surplus at the plant intake, which will be used for

the treatment process. As for practical reasons this indicator only uses electrical energy ac-

cording to the consumption of the low voltage busbar, the denominator may not correspond to

the entire energy utilised for water treatment.

The processing rule of this indicator assumes that no component is used requiring high voltage

power supplies. If this is not the case (e.g. reverse osmosis plants and other advanced treat-

ment technologies) the user needs to create a new variable assessing high voltage power con-

sumption utilised for water treatment that needs to be added to the processing rule as denomi-

nator.

Special care is required in interpreting results when used for external comparisons. The overall

energy consumption will vary widely according to the utilised process engineering.


Page 65

wsEc5a – overall plant energy consumption per volume produced (kWh/m³) al

tern

ativ

e in

dica

tor

overall waterworks facility energy consumption / drinking water production vol-ume




This indicator provides a measure of energy utilisation by the treatment process in rela-

tion to the production volume during the assessment period.

As this indicator does not consider treatment, operational consumption and losses, it

should only be used if indicator wsEc5 cannot be calculated due to the lack of a water

meter at the plant raw water intake valve.

In some cases, raw water will have an energy surplus at the plant intake, which will be

used for the treatment process. As for practical reasons this indicator only uses electrical

energy according to the consumption of the low voltage busbar, the denominator may

not correspond to the entire energy utilised for water treatment.

The processing rule of this indicator assumes that no component is used requiring high

voltage power supplies. If this is not the case (e.g. reverse osmosis plants and other ad-

vanced treatment technologies) the user needs to create a new variable assessing high

voltage power consumption utilised for water treatment that needs to be added t o the

processing rule as numerator.

Special care is required in interpreting results when used for external comparisons. The

overall energy consumption will vary widely according to the utilised process engineer-

ing. Usual values are around 0.03 kWh/m³ (classic treatment), 0.12 kWh/m³ (activated

carbon and ozone), 0.2 kWh/m³ (membrane ultrafiltration), 2 to 5.6 kWh/m³ (multistage

flash evaporation and multiple effect distillation) and 4 kWh/m³ for reverse osmosis (but it

may reach up to 7 kWh/m³ with a particularly poor raw water resource).


Page 66

wsEc6 – heat demand per volume produced (kWh/m³)

energy consumption water treatment / drinking water production volume

wsEc6 = wsC6 / wsW5

wsC6– heat demand (kWh)


This indicator provides a measure of heat energy utilisation by evaporators in relation to the

production volume during the assessment period of desalination plants using either multistage

flash evaporation (MSF) or multiple effect distillation (MED) process engineering. Usual values

are around 64 kWh/m³ for MSF plants and 54 kWh/m³ for MED plants.

wsEc7 – standardised energy consumption main pumps (kWh/m³/100 m)

energy consumption drinking water main pumps / drinking water production volume / pump head drinking water main pumps x 100




wsH3 – pump head drinking water main pumps (m)

This indicator provides a measure of the energy conversion efficiency of the main pumps feed-

ing the transmission lines operated by the undertaking. It equals the average amount of energy

consumed per m³ at a pump head of 100 m. It is the inverse of the pumping efficiency. A value

of 0.5 kWh/m³/100m for this indicator corresponds to an average pumping efficiency of 9810 N

x 100 m / (3600 J/Wh) / 500 Wh x 100 = 55%.

Usual values for drinking water main pumps are between 50% and 70%.


Page 67

wsEc7a – energy consumption main pumps (kWh/m³) al

tern

ativ

e in

dica

tor

energy consumption drinking water main pumps / drinking water production vol-ume




This indicator provides a measure of the energy conversion efficiency of the drinking

water booster pumps operated by the undertaking. As this indicator does not consider

pump head, it should be only used if indicator wsEc7 cannot be calculated.

wsEc8 – standardised energy consumption booster pumps (kWh/m³/100 m)

energy consumption drinking water booster pumps / pressure boosted drinking water volume / pump head drinking water booster pumps x 100




wsH4 – pump head drinking water booster pumps (m)

This indicator provides a m easure of the energy conversion efficiency of the drinking water

booster pumps operated by the undertaking. It equals the average amount of energy con-

sumed per m³ at a pump head of 100 m. It is the inverse of the pumping efficiency. A value of

0.5 kWh/m³/100m for this indicator corresponds to an average pumping efficiency of 9810 N x

100 m / (3600 J/Wh) / 500 Wh x 100 = 55%.

Usual values for drinking water booster pumps are between 50% and 70%.


Page 68

wsEc8a – energy consumption booster pumps (kWh/m³)

alte

rnat

ive

indi

cato

r

energy consumption drinking water booster pumps / pressure boosted drinking water volume




This indicator provides a m easure of energy utilisation of the drinking water booster

pumps operated by the undertaking in relation to the pressure boosted drinking water

volume during the assessment period. As this indicator does not consider pump head, it

should only be used if indicator wsEc8 cannot be calculated.

Performance indicators addressing energy production (indicators wsEp)

wsEp1 – total energy recovery (%)

total energy recovered / total pumping energy consumption x 100

wsEp1 = wsP1 / wsC1 x 100

wsP1 – total energy recovered (kWh)


This indicator provides a measure of recovery of surplus energy for hydraulic transport needs

by use of turbines or reverse pumps during the assessment period. It can be used as a meas-

ure of how well energy recovery efforts are globally evolving.

At favourable geomorphologic conditions, up to 40% of the pumping energy may be recovera-

ble.


Page 69

wsEp2 – total energy production other than recovery (%)

total energy recovered / total energy consumption for water supply division x 100

wsEp2 = wsP2 / wsC1 x 100

wsP2 – total energy produced other than recovered (kWh)


This indicator provides a m easure of production of renewable energy on the undertaking’s

premises in order to cover parts of its energy demand for water supply. It can be used as a

measure of how well energy production efforts are globally evolving.

Performance indicators addressing monetary costs (indicators wsMc)

wsMc1 – electrical energy cost (Dollar/kWh)

total energy costs / total energy consumption for water supply division

wsMc1 = wsM1 / wsC1

wsM1 – total energy costs (Dollar)


This indicator provides a measure of the average cost of energy per unit of procurement. It is

largely dependent on both national energy policy and the context within which the undertaking

operates (e.g. distribution of nominal power of energy consuming components along the sys-

tem). Thus, special care is required in interpreting results when used for external comparisons.


Page 70

Waste Water Disposal Data Variables (Variables wd)

Data variables addressing monetary cost of energy (variables wdM)

wdM1 – total energy costs (Dollar)

Costs of electrical energy (including energy for waste water pumping, treatment and all other activities related to waste water disposal, e.g. energy for premises, offices) during the assessment period.

INPUT DATA



This variable includes not only the component proportional to the energy consumption but all

the other costs associated with energy purchases such as power tariffs and taxes. Data is to be

derived from the financial statement of the undertaking. Exchange rates of local currencies

should be referred to at the end of the assessment period.

Used for indicator(s): wdMc1

Data variables addressing energy consumption (variables wdC)

wdC1 – total energy consumption for waste water disposal division (kWh)

Electrical energy consumption (including energy for waste water pumping and treatment as well as all other activities related to waste water disposal, e.g. energy for premises, offices etc.) during the assessment period.

INPUT DATA



This variable is the total energy consumption of the waste water disposal division or undertak-

ing. If there is no energy production data is to be derived from the bills of the energy supplier.

Used for indicator(s): wdEc1, wdEc1a, wdMc1


Page 71

wdC2 – energy consumption lifting pumps in sewer system (kWh)

Electrical energy consumption of each pumping component in the sewer system during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every pumping component in the sewer sys-

tem. Data is to be derived from energy consumption meters or from the bills of the energy sup-

plier. If the consumption is not shown on a separate bill and no meter is installed, it needs to be

measured for all relevant operating states of the component on-site. Measured data may be

projected for the whole period. If this procedure is too time consuming, for non-power-

controlled pumps it may be r easonably estimated by multiplying pump nominal power with

pump working hours during the assessment period. If in a particular case a fuel driven pump is

to be assessed, the amount of diesel needs to be converted to power using its specific heating

value and the mechanical efficiency of the engine.

Used for indicator(s): wdEc2, wdEc2a

wdC3 – overall waste water treatment plant energy consumption (kWh)

Electrical energy consumption (including waste water, sludge treatment, premises) dur-ing the assessment period.

INPUT DATA



The data variable is to be assessed for each and every waste water treatment plant of the un-

dertaking. Data is to be derived from energy consumption meters or from the bills of the energy

supplier. If consumption is derived from bills of the energy supplier, self produced and con-

sumed energy has to be added.



Page 72

wdC4– energy consumption water pumps on waste water treatment plants (kWh)

Energy consumption of each pumping component in the water path of the undertaking’s waste water treatment plants during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every pumping component in the water path

of each and every waste water treatment plant. Data is to be derived from energy consumption

meters. If no meter is installed, it needs to be measured for all relevant operating states of the

component on-site. Measured data may be projected for the whole period. If this procedure is

too time consuming, for non-power-controlled pumps it may be reasonably estimated by multi-

plying pump nominal power with pump working hours during the assessment period.


wdC5 – energy consumption aeration component (kWh)

Energy consumption of the aeration system in the biological treatment stage during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every waste water treatment plant of the un-

dertaking. Data is to be derived from energy consumption meters. If no meter is installed, it

needs to be measured for a limited period and then projected for the whole assessment period.

Used for indicator(s): wdEc5


Page 73

wdC6 – energy consumption sludge treatment (kWh)

Electric energy consumption of the sludge treatment components during the assess-ment period.

INPUT DATA



The variable should be assessed for each and every treatment plant of the undertaking. The

variable corresponds to the entire electric energy consumption of all relevant sludge treatment

components such as sludge pumps, mechanical dewatering units (during and before the final

treatment stage used to decrease sludge volume or water amount), mixers, chemical dosing

stations, mechanical sludge-drying units (e.g. filter press), drainage pumps and al l other rele-

vant components. Data is to be der ived from energy consumption meters. If no meter is in-

stalled, it needs to be estimated by the best means available.


wdC7 – energy consumption sludge pumps on waste water treatment plants (kWh)

Energy consumption of each pumping component in the sludge path of the undertak-ing’s waste water treatment plants during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every pumping component in the sludge lines

of each and every waste water treatment plant. Data is to be derived from energy consumption

meters. If no meter is installed, it needs to be measured for all relevant operating states of the

component on-site. Measured data may be pr ojected for the whole period. When this is too

time consuming, for non-power-controlled pumps it may be reasonably estimated by multiplying

pump nominal power with pump working hours during the assessment period.



Page 74

wdC8 – heat demand (kWh)

Heat demand of digesters in treatment plants utilising anaerobic sludge digestion during the assessment period.

INPUT DATA



The variable should be assessed for each and every treatment plant of the undertaking utilising

anaerobic sludge digestion. The variable corresponds to the heat energy that has been p ro-

duced in order to be utilised for heating the digesters.


wdC9 – energy consumption tertiary treatment stage (kWh)

Energy consumption of the components in waste water treatment plants with a tertiary treatment stage during the assessment period.

INPUT DATA



The variable should be assessed for each and every treatment plant of the undertaking apply-

ing one or more tertiary treatment process as advanced treatment stage such as filtration, la-

gooning, nutrient removal, phosphor removal, heavy metals removal and disinfection. The vari-

able corresponds to the entire energy consumption of all relevant components of the tertiary

treatment stage such as centrifugal pumps feeding of the sand filters, drum filters, chemical

dosing pumps, UV radiators, the ozonation system and all other relevant components. Data is

to be derived from energy consumption meters. If no meter is installed, it needs to be estimated

by the best means available.



Page 75

Data variables addressing energy production (variables wdP)

wdP1 – total energy recovery from biogas (kWh)

Total energy recovered from biogas at waste water treatment plants utilising anaerobic sludge digestion during the assessment period.

INPUT DATA



The data variable is to be assessed for the entire waste water disposal division of the undertak-

ing taking all waste water treatment plants into account where energy is recovered from biogas

produced in the digesters. Ways of recovering energy from biogas may include production of

heat for re-use on-site, simultaneous production of electricity and heat re-used on-site (cogen-

eration) but also biofuel production as well as conversion of biogas into biomethane for injec-

tion into the natural gas network or in electrical form for injection into the electricity network (if

there is more on-site energy production than demand). The variable only corresponds to the

amount of energy that has been recovered by the undertaking in order to cover parts of its en-

ergy demand for waste water treatment processes.

Used for indicator(s): wdEp1


Page 76

wdP2 – total energy produced other than from biogas (kWh)

Total energy produced by means of e.g. photovoltaic, wind turbines etc. at the premises of the entire waste water disposal division of the undertaking during the assessment period.

INPUT DATA




ing. Energy production relates to the amount of energy produced from renewable sources on-

site on the entire premises of the waste water disposal division/undertaking in order to cover

parts of its energy demand for waste water disposal.


wdP3 – electric energy production by cogeneration (kWh)

Electric energy produced from biogas by combined heat and power co-generators dur-ing the assessment period.

INPUT DATA



The variable should be assessed for each and every treatment plant of the undertaking where

combined heat and power co-generators are installed to recover energy from the biogas pro-

duced in the digesters. The variable corresponds to the entire electrical energy production of

the plant regardless of its use.



Page 77

wdP4 – volume of biogas production (m³)

Volume of biogas generated during the assessment period.

INPUT DATA




anaerobic sludge digestion. The volume should be declared as the standard cubic metre and

based on standard temperature and pressure at 0° C and 1013 bar.

Used for data variable(s): wdP5


wdP5 – energy content of biogas production (kWh)

Energy content of biogas generated during the assessment period.

INPUT DATA




anaerobic sludge digestion. The energy content can be der ived by multiplying plant specific

volume of biogas production (data variable wdP4) with its specific heating value.



Page 78

Data variables addressing water volumes (variables wdW)

wdW1 – total volume of waste water treated (m³)

Total volume of waste water treated by waste water treatment plants operated by the undertaking during the assessment period.

INPUT DATA




ing. It corresponds to the entire waste water volume that has been treated on all waste water

treatment plants regardless of the required quality of the discharge. Waste water treated by on-

site systems operated by the undertaking is not to be included.

Used for indicator(s): wdEc1a

wdW2 – volume of waste water treated (m³)

Volume of waste water treated during the assessment period.

INPUT DATA



The variable should be assessed for each and every treatment plant operated by the undertak-

ing. It corresponds to the volume that has been treated during the assessment period resulting

from collected sewage, rainwater and i nfiltration volumes. It should be derived from the inlet

flow measurements.

Used for indicator(s): wdEc3a


Page 79

wdW3 – lifted volume (m³)

Volume of waste water lifted by each pumping component in the sewer system during the assessment period.

INPUT DATA




tem. Data can be derived by reading installed flow meters. If there is no flow meter installed or

no record available, it needs to be estimated by the best means available.


wdW4 – waste water volume elevated (m³)

Volume of waste water pumped by each pumping component in the water path of the undertaking’s waste water treatment plants during the assessment period.

INPUT DATA




of each and every waste water treatment plant. Data is to be derived from meter readings. If


means available.



Page 80

wdW5 – waste water receiving tertiary treatment (m³)

Volume of waste water receiving tertiary treatment during the assessment period.

INPUT DATA



The variable should be assessed for each and every treatment plant of the undertaking apply-

ing one or more tertiary treatment process such as filtration, lagooning, nutrient removal or dis-

infection. The variable corresponds to the volume delivered to the application that reuses treat-

ed waste water (e.g. irrigation, watering of golf courses and public gardens). Data is to be ei-

ther derived from the meter readings or from invoices issued to the re-users.


Data variables addressing sludge volumes (variables wdS)

wdS1 – sludge volume handled (ton DS)

Dry weight of sludge handled during the assessment period.

INPUT DATA



All dry weight of sludge handled by the undertaking during the assessment period, including

not only the dry weight of sludge produced in the waste water treatment plants, but also dry

weight of sludge inputs from other sources. Sludge handled may also include sludge from on-

site systems. If applicable, the value should be obtained before digestion.

The variable must be entered as dry solids, e.g. if the handled amount is 20 tons of sludge and

the percentage of dry solids is 30%, then dry solids are equal to 20 tons x 0.3 = 6 tons dry sol-

ids.



Page 81

wdS2 – sludge volume elevated (m³)

Volume of sludge pumped by each pumping component in the sludge path of the under-taking’s waste water treatment plants during the assessment period.

INPUT DATA



The data variable is to be assessed for each and every pumping component in the sludge path

of each and every waste water treatment plant. Data is to be derived from meter readings. If


means available.



Page 82

Data variables addressing pollution loads (variables wdL)

wdL1 – total population equivalents served (PT)

Total population equivalents that were connected to waste water treatment plants oper-ated by the undertaking during the assessment period.

INPUT DATA




ing. It corresponds to the entire load that was connected to all waste water treatment plants

regardless of the required quality of the discharge. On-site systems operated by the undertak-

ing are not to be included.

The pollution load should be measured at the intakes of the waste water treatment plants oper-

ated by the undertaking. It is recommended to have a minimum set of at least twelve samples

(one 24-hour sample for each month) available to assess the data variable. Reflux from sludge

treatment is not to be taken into account.

Population equivalents should be calculated using the standard pollution load of sewage gen-

erated by one inhabitant (based on BOD5) corresponding with the national or regional norm. If

there is no norm available, a value of 60 g/d should be applied.



Page 83

wdL2 – population equivalents served (PT)

Connected population equivalents during the assessment period.

INPUT DATA



The variable should be assessed for each and every treatment plant operated by the undertak-

ing.

The pollution load should be measured at the inflow of the waste water treatment plant. It is

recommended to have a minimum set of at least twelve samples (one 24-hour sample for each

month) available to assess the data variable.

Population equivalents should be calculated using the standard pollution load of sewage gen-

erated by 1 i nhabitant (based on BOD5) corresponding with the national or regional norm. If

there is no norm available, a value of 60 g/d may be used.

Used for indicator(s): wdEc3, wdEc5, wdEc8, wdEp3

Data variables addressing pump heads (variables wdH)

wdH1 – pump head lifting pumps (m)

Pump head for each pumping component in the sewer system during the assessment period.

INPUT DATA




tem. For pumps with significant variation of the pump head throughout the assessment period,

the period should be subdivided into a limited number of time intervals. For instance, if a pump

works 1/3 of the time with a flow Q1 = 10 m³/h and a pump head of h1 = 50 m, and 2/3 of the

time with a f low Q2 = 12 m³/h and a pum p head h2 = 42 m, the resulting pump head will be: (

(1/3) x Q1 x h1 + (2/3) x Q2 x h2 ) / ( (1/3) x Q1 + (2/3) x Q2 ) = 44.35 m



Page 84

wdH2 – pump head water pumps (m)

Pump head for each pumping component in the water path of the undertakings waste water treatment plants during the assessment period.

INPUT DATA




of each and every waste water treatment plant. For pumps with significant variation of the

pump head throughout the assessment period, the period should be subdivided into a limited

number of time intervals. For instance, if a pump works 1/3 of the time with a flow Q1 = 10 m³/h

and a pump head of h1 = 50 m, and 2/3 of the time with a flow Q2 = 12 m³/h and a pump head

h2 = 42 m, the resulting pump head will be: ( (1/3) x Q1 x h1 + (2/3) x Q2 x h2 ) / ( (1/3) x Q1 +

(2/3) x Q2 ) = 44.35 m



Page 85

Waste Water Disposal Energy Check Key Performance Indicators

Performance indicators addressing energy consumption (indicators wdEc)

wdEc1 –energy consumption per population equivalent served (kWh/PT)

total energy consumption for waste water disposal / total population equivalents

wdEc1 = wdC1 / wdL1


wdL1 – total population equivalents served (PT)

This indicator provides a measure of the necessary electrical energy utilisation by the undertak-

ing in relation to the population equivalents served during the assessment period. It can be

used as a measure of how well energy efficiency improvement efforts are globally evolving.

Main explanatory factors for external comparison:

• Energy conversion efficiency of the pumps

• Utilised process engineering for waste water and sludge treatment

• Geomorphology of the catchment area

• Reactive energy consumption

Usual values are between 30 kWh/PT and 80 kWh/PT


Page 86

wdEc1a – energy consumption per waste water volume disposed (kWh/m³)

alte

rnat

ive

indi

cato

r

total energy consumption for waste water disposal / total volume of waste water treated

wdEc2 = wdC1 / wdW1


wdW1 – total volume of waste water treated (m³)

This indicator provides a m easure of the necessary electrical energy utilisation by the

undertaking in relation to the volume of waste water disposed of during the assessment

period. It can be used as a measure of how well energy efficiency improvement efforts


As the major part of energy consumption for waste water disposal is usually related to

the pollution load rather than the hydraulic load, the indicator should only be applied if

indicator wdEc1 cannot be calculated.


Page 87

wdEc2– standardised energy consumption lifting pumps in sewer system (kWh/m³/100 m)

energy consumption lifting pumps in sewer system / lifted volume / pump head lifting pumps x 100

wdEc3 = wdC2 / wdW3 / wdH1 x 100



wdH1 – pump head lifting pumps (m)

This indicator provides a measure of the energy conversion efficiency of the lifting pumps in the

sewer system operated by the undertaking. It equals the average amount of energy consumed

per m³ at a pump head of 100 m. It is the inverse of the pumping efficiency. A value of 0.5


m / (3600 J/Wh) / 500 Wh x 100 = 55%.

For external comparison, it may be specified whether the assessed lifting pump elevates waste

water, storm water or sewage.

Usual values for lifting pumps are between 11% and 56%.


Page 88

wdEc2a – energy consumption lifting pumps in sewer system (kWh/m³)

alte

rnat

ive

indi

cato

r

energy consumption lifting pumps in sewer system / lifted volume

wdEc3 = wdC2 / wdW3



This indicator provides a m easure of the energy consumption of lifting pumps in the

sewer system operated by the undertaking in relation to the volume lifted during the as-

sessment period. As this indicator does not consider pump head, it should only be used

if indicator wdEc3 cannot be calculated.

For external comparison, it may be specified whether the assessed lifting pump elevates

waste water, storm water or sewage.

wdEc3 – overall plant energy consumption per population equivalent served (kWh/PT)

overall waste water treatment plant energy consumption / population equivalents

wdEc3= wdC3 / wdL2



This indicator provides a measure of energy utilisation by the treatment process in relation to

the population equivalents served during the assessment period.

Special care is required in interpreting results when used for external comparisons. The overall

energy consumption will vary widely according to its treatment capacity, utilised process engi-

neering for both, water and sludge treatment, the waste water composition as well as the re-

quired quality of the discharge.


Page 89

wdEc3a – overall plant energy consumption per volume of waste water treated (kWh/m³) al

tern

ativ

e in

dica

tor

overall waste water treatment plant energy consumption / volume of waste water treated

wdEc3a= wdC3 / wdW2


wdW2 – volume of waste water treated (m³)

This indicator provides a measure of energy utilisation by the treatment process in rela-

tion to the volume of waste water treated during the assessment period.

As the major part of energy consumption for waste water treatment is usually related to

the pollution load rather than the hydraulic load, the indicator should only be applied if

indicator wdEc3 cannot be calculated.

Special care is required in interpreting results when used for external comparisons. The

overall energy consumption will vary widely according to its treatment capacity, utilised

process engineering for both, water and sludge treatment, the waste water composition

as well as the required quality of the discharge.


Page 90

wdEc4 – standardised energy consumption pumps for water treatment (kWh/m³/100 m)

energy consumption water pumps on waste water treatment plants / waste water volume elevated / pump head water pumps x 100

wdEc4 = wdC4 / wdW4 / wdH2 x 100

wdC4 – energy consumption water pumps on waste water treatment plants (kWh)


wdH2 – pump head water pumps (m)

This indicator provides a measure of the energy conversion efficiency of the water pumps on-

site on waste water treatment plants operated by the undertaking. It equals the average

amount of energy consumed per m³ at a pump head of 100 m. It is the inverse of the pumping

efficiency. A value of 0.5 kWh/m³/100m for this indicator corresponds to an average pumping

efficiency of 9810 N x 100 m / (3600 J/Wh) / 500 Wh x 100 = 55%.

Usual values for water pumps within waste water treatment are between 45% and 68%.

wdEc4a –energy consumption pumps water treatment (kWh/m³)

alte

rnat

ive

indi

cato

r

energy consumption water pumps on waste water treatment plants / waste water volume elevated

wdEc4a = wdC4 / wdW4

wdC4 – energy consumption water pumps on waste water treatment plants (kWh)


This indicator provides a measure of the energy conversion efficiency of the water

pumps on-site on waste water treatment plants operated by the undertaking in relation to

the volume elevated during the assessment period. As this indicator does not consider

pump head, it should only be used if indicator wdEc4 cannot be calculated.


Page 91

wdEc5 – energy consumption biological aeration (kWh/PT)

energy consumption aeration component / population equivalents served

wdEc5 = wdC5 / wdW4

wdC5 – energy consumption aeration component (kWh)


This indicator provides a measure of energy utilisation by the aeration system in relation to the

population equivalents served during the assessment period.

Special care is required in interpreting results when used for external comparisons. Energy

consumption for biological aeration will vary according to the design of the aeration tanks to

allow efficient mixing, the air production machines utilised, the type of sparger and the system

for regulating the biological aeration to meet the exact air requirement of the purifying bacteria.

Usually, biological aeration accounts for more than 40% of a plants energy consumption.

wdEc6 – energy consumption sludge treatment (kWh/ton DS)

energy consumption sludge treatment / sludge volume handled

wdEc6 = wdC6 / wdS1

wdC6 – energy consumption sludge treatment (kWh)

wdS1 – sludge volume handled (ton DS)

This indicator provides a measure of energy utilisation by the sludge treatment process in rela-

tion to the dry weight of sludge handled during the assessment period.


consumption for sludge treatment depends on the type of technology used. In general, for

sludge from extended aeration, almost all treatment types are more energy-intensive than for

mixed sludge.


Page 92

wdEc7 –energy consumption sludge pumping (kWh/m³)

energy consumption sludge pumps on waste water treatment plants / sludge volume elevated

wdEc7 = wdC7 / wdS2

wdC7 – energy consumption sludge pumps on waste water treatment plants (kWh)

wdS2 – sludge volume elevated (m³)

This indicator provides a m easure of the energy consumption of the sludge pumps on-site

waste on water treatment plants operated by the undertaking in relation to the volume elevated

during the assessment period.

wdEc8 – heat demand per population equivalent served (kWh/PT)

heat demand / population equivalents served

wdEc8 = wsC8 / wdL2

wdC8– heat demand (kWh)


This indicator provides a measure of heat energy utilised for heating the digesters in relation to

the population equivalents served during the assessment period. Although thermal energy

usually is of minor significance the thermal indicator completes the energy check


Page 93

wdEc9 –energy consumption tertiary treatment (kWh/m³)

energy consumption tertiary treatment stage / waste water receiving tertiary treatment

wdEc9= wdC9 / wdW5

wdC9 – energy consumption tertiary treatment stage (kWh)

wdW5 – waste water receiving tertiary treatment (m³)

This indicator provides a m easure of the energy consumption of the tertiary treatment stage

operated by the undertaking in relation to the volume of waste water receiving tertiary treatment

during the assessment period.


consumption for tertiary treatment depends on the quality required by the final use of the water

that determines both the kind of treatment technologies and their sophistication.

Performance indicators addressing energy production (indicators wdEp)

wdEp1 – total energy recovery from biogas (%)

total energy recovered / total energy consumption for waste water disposal division x 100

wdEp1 = wdP1 / wdC1 x 100

wdP1 – total energy recovery from biogas (kWh)


This indicator provides a measure of energy recovery from biogas generated during anaerobic

sludge digestion. It can be used as a measure of how well energy recovery efforts from biogas



Page 94

wdEp2 – total energy production other than from biogas (%)

total energy produced other than from biogas / total energy consumption for waste wa-ter disposal division x 100

wdEp2 = wdP2 / wdC1 x 100

wdP2 – total energy produced other than from biogas (kWh)


This indicator provides a m easure of production of renewable energy on the undertaking’s

premises in order to cover parts of its energy demand for waste water disposal. It can be used

as a measure of how well energy production efforts are globally evolving.

wdEp3 –biogas generation per population equivalent (kWh/PT)

volume of biogas production / population equivalents served

wdEp3= wdP4 / wdL2

wdP4 – volume of biogas production (m³)


This indicator provides a measure of the biogas generation in relation to the load during the

assessment period.

Special care is required in interpreting results when used for external comparisons since the

reception of co-substrates will have a great influence of the value. As for practical reasons this

indicator only uses population equivalents as the denominator, the user might create a new

variable assessing the organic dry solid matter of the sludge feeding the digesters.


Page 95

wdEp4 – proportion of biogas conversion into energy (%)

electric energy production by cogeneration / energy content of biogas production x 100

wdEp3= wdP3 / wdP5 x 100

wdP3 – electric energy production by cogeneration (kWh)

wdP5 – energy content of biogas production (kWh)

This indicator provides a measure of the proportion of biogas that was converted to electricity

during the assessment period. Ideally, the entire biogas volume should be utilized. However,

due to maintenance of the combined heat and power co-generators and thanks to non-uniform

gas production in combination with too small or even non-existing gas storage tanks, losses

through flaring will occur.

Performance indicators addressing monetary costs (indicators wdMc)

wdMc1 – electrical energy cost (Dollar/kWh)

total energy costs / total energy consumption for waste water disposal division

wdMc1 = wdM1 / wdC1

wdM1 – total energy costs (Dollar)


This indicator provides a measure of the average cost of energy per unit of procurement. It is

largely dependent on both national energy policy and the context within which the undertaking

operates (e.g. distribution of nominal power of energy consuming components along the sys-

tem). Thus, special care is required in interpreting results when used for external comparisons.

DWA-A 216 Frequency Distributions

Page 96


Specific total power consumption

Specific power consumption aeration

Source: DWA, DWA-A 216: Energy check and energy analysis – tools for energy optimization of waste water plants.

Germany, 2013, Gelbdruck April 2013


Page 97

Specific production of digester gas




Page 98

Degree of digester gas conversion in electricity

Self supply with electricity




Page 99

Specific external thermal (heat) requisition

Specific power consumption pumps



Example List of Machines

Page 100

Example List of Machines

proc

ess

step

mac

hine

cons

truct

ion

year

rate

d po

wer

ca

paci

ty

[kW

]

oper

tion

hour

s[h

/a]

activ

e po

wer

[A]

volta

ge[k

V]

appa

rent

po

wer

[k

VA]

cos

phi

[-]

activ

e po

wer

[k

W]

pow

er

cons

umpt

ion

[kW

h/a]

mac

hine

1m

achi

ne2

mac

hine

3m

achi

ne4

mac

hine

5m

achi

ne6

mac

hine

1m

achi

ne2

mac

hine

3m

achi

ne4

mac

hine

5m

achi

ne6

mac

hine

1m

achi

ne2

mac

hine

3m

achi

ne4

mac

hine

5m

achi

ne6

mac

hine

1m

achi

ne2

mac

hine

3m

achi

ne4

mac

hine

5m

achi

ne6

proc

ess

step

1

proc

ess

step

2

proc

ess

step

3

proc

ess

step

4

Energy Analysis Calculation of the Theoretical Values

Page 101


Water Supply

Waste intake, transmission, treatment, storage

pumping station [kWh]

E = (Q · h · 2.7) / (ηM · ηP · 1000)

Q = amount of water [m³/a]


ηM = efficiency of engine [%]

ηP = efficiency of the pump [%]

Infrastructure

power consumption of building [kWh]

E = esp · A

esp = specific energy consumption ( 12 to 16 kWh/m², )

A = area of the buildings including every room [m²]

heating of buildings [kWh]

E = esp · A

esp = specific energy consumption (60 kWhTh/m²)



Page 102

cooling of buildings [kWh]

E = esp · A

esp = specific energy consumption (25 kWh/m²)


ventilation of buildings [kWh]

E = esp · QL · t

esp = specific energy consumption ( 5 to 8 kWh/1.000 Nm³/d )

QL = airflow rate [Nm³/h]


other machines [kWh]

E = P · t · (0.7 to 0.9)

P = rated power capacity [kW]



Page 103


Waste Water


E = (Q · h · 2.7) / (ηM · ηP · 1000)

Q = amount of water [m³/a]




screen [kWh]

E = esp · PTBOD

esp = specific energy consumption ( 0.05 to 0.1 kWh/(PT·a)

PTBOD = total number of population equivalents [PT]

aeration of grit chamber [kWh]

E = ((QL · h) / (ηa · 367)) · t



ηa = efficiency of blower [%]



Page 104

scraper of grit chamber [kWh]

E = P · t · (0.7 to 0.9)



primary sedimentation (scraper) [kWh]

E = P · t · (0.7 to 0.9)



aeration of the biological tank [kWh]

E = ((QL · h) / (ηa · 367)) · t



ηa = efficiency of blower [%]



Page 105

stirrer of the biological tank [kWh]

E = v · esp · t / 1000

v = volume of the tank [m³]

esp = specific energy consumption (1.5 to 4.0 W/m³ depending on absolute volume)


secondary sedimentation (scraper) [kWh]

E = P · t · (0.7 to 0.9)



stirrer of the storage tank [kWh]

E = v · esp · t / 1000

v = volume of the tank [m³]



filtration [kWh]

E = esp · Q

esp = specific energy consumption ( 4.2 to 7.4 kWh/m³)

Q = amount of water in filtration [m³/a]


Page 106


E = P · t · (0.7 to 0.9)



Sludge


E = (Q · h · 2.7) / (ηM · ηP · 1000)

Q = amount of sludge [m³/a]




sludge thickening [kWh]

E = esp · QS

esp = specific energy consumption ( 0.2 to 1.6 kWh/m³ depending on the process)

QS = amount of sludge in thickening [m³/a]


Page 107

sludge heating [kWh]

E = QS · ΔT · ηTh · esp


ΔT = difference in temperature [K]

ηTh = efficiency of heating [%]

esp = specific energy consumption (1.16 kWhth/(m³·K))

anaerobic sludge digestion [kWh]

E = esp · QS

esp = specific energy consumption (1.6 to 2.3 kWh/m³)


stirrer of digester [kWh]

E = v · esp · t / 1000

v = volume of the digester [m³]




Page 108

transmission-heat-loss of digestion [kWh]

E = A · ΔT · esp · 8,760 h/a

A = surface of the digester [m²]

ΔT = difference in temperature [K]

esp = specific energy consumption (0.0003 to 0.0005 kW/(m³·K))

sludge dewatering [kWh]

E = esp · QS

esp = specific energy consumption (0.05 to 3.4 kWh/m³ depending on the process)


Other machines [kWh]

E = P · t · (0.7 to 0.9)



Energy

power production combined heat and power CHP [kWh]

E = ηEl · EB · NCHP

ηEl = electric efficiency of the CHP [%]

EB = caloric value of the biogas produced [kWh/m³]

NCHP = rate of biogas use in the CHP


Page 109

heat production combined heat and power CHP [kWh]

E = ηTh · EB · NCHP

ηTH = thermal efficiency of the CHP [%]

EB = caloric value of the biogas produced [kWh/m³]

NCHP = rate of biogas use in the CHP

Infrastructure

power consumption of building [kWh]

E = esp · A

esp = specific energy consumption ( 12 to 16 kWh/m², )


heating of buildings [kWh]

E = esp · A

esp = specific energy consumption (60 kWhTh/m²)


cooling of buildings [kWh]

E = esp · A

esp = specific energy consumption (25 kWh/m²)



Page 110

ventilation of buildings [kWh]

E = esp · QL · t

esp = specific energy consumption ( 5 to 8 kWh/1.000 Nm³/d)




E = P · t · (0.7 to 0.9)



Documents

Guidelines for Energy Checks and Energy Analysis in · PDF fileGuidelines for Energy Checks and Energy Analysis in Water and Wastewater Utilities November 2014. ... thermal efficiency