Cogeneration: Energy Production maximising Efficiency and minimising Environmental ... · 2014-12-04 · Cogeneration: Energy Production maximising Efficiency and ... Total Efficiency

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Cogeneration: Energy Production maximising Efficiency and

minimising Environmental Impact at all scales

Dr. Ing. Petru Ruset, Siemens srl, Romania

20th – 22nd of November 2014

Restricted © Siemens AG 20XX All rights reserved.

2014-11-20 Dr. Ing. Petru Ruset/Energy Management DivisionPage 2

• What is Cogeneration ? 3

• Utilizing Natural Gas 5

• Cogeneration Applications 7

• Cogeneration Technologies 8

• Choosing a Technology 9

• Alternative Fuel Options 16

• Conclusions 17

Cogeneration

Table of content


2014-11-20Page 3

What is Cogeneration ?

Definition

‘The simultaneous production of both heat

and power from a single source’

• Cogeneration can be:

• Topping Cycle

• Focused on electricity production with wasted

energy used to provide heat

• Bottoming Cycle

• Focused on heat production, with surplus energy

used to produce electricity

Dr. Ing. Petru/Ruset/Energy Management Division


2014-11-20Page 4

What is Cogeneration ?

A properly designed Cogeneration plant is the most efficient way to meet site energy demands

Fuel

100%

25 -

55%

75 -

85%

Electricity

Remote

Power

Plant

On-site

Boiler

Steam

Losses 10 -

20%

T&D losses

circa 5%

Steam

distribution losses

Fuel

100%

Overall Energy Efficiency = 50 – 70%

Losses 40 - 70%

On-site

Cogeneration

Plant

Fuel

100%

> 30%

Electricity

Steam

Losses < 25%

Steam distribution

losses

> 45%

Overall Energy Efficiency: > 75%

Dr. Ing. Petru Ruset/Energy Management


2014-11-20Page 5

Utilizing Natural Gas

Why use Natural Gas ?

• Widespread availability

• Reserves for > 150 years consumption

• Transportable

• Pipeline

• LNG

• CNG

• Can be stored to provide strategic reserve

• Underground Gas Storage (UGS)

• LNG

• Competitively priced

Dr. Ing. Petru Ruset/Energy Management Division


2014-11-20Page 6

Utilizing Natural Gas

Why use Natural Gas ?

• ‘Clean’ fossil fuel

• Low carbon content = low CO2 emissions

• Clean burning, low pollutants

• No SOx

• No particulate

• Clean Combustion Technologies

• Low NOx

• Low CO

• Low Unburned Hydrocarbons• Caution: Methane Slip on Gas and Dual Fuel Engines

• Saves money and protects the Environment !0

0.05

0.1

0.15

0.2

0.25

0.3

0.35

0.4

0.45

Natural

Gas

Diesel Coal Lignite Wood MSW (non-

Biomass)

CO2 Emission Factors (T per MWh)



2014-11-20Page 7

Cogeneration Applications

Cogeneration can be applied at any scale where

there is both a power and heat (or cooling) demand

• From a few kW to 100’s of MW

• Domestic

• Commercial

• Municipal

• District Heating/Cooling

• Hospitals / Swimming Pools

• Universities

• Industrial

• Chemicals, Pharmaceuticals, Food & Drink,

Automotive, Pulp & Paper, Textiles, Ceramics…



2014-11-20Page 8

Cogeneration Technologies

A range of potential technologies exists

• Applicability often dependent on scale

MicroturbineReciprocating Engine

(Gas Engine)

Increasing Power

Reciprocating Engine

(Gas Engine)Gas Turbine Steam Turbine

Domestic Commercial Municipal Industrial

Stirling Engine

Reciprocating

Engine (Gas

Engine)



2014-11-20Page 9

Choosing a Technology

Gas Turbines, Steam Turbines and Gas Engines

dominate the Cogeneration market

• Gas Turbines have the vast majority of recoverable

heat in the high temperature exhaust gases

• 30kW – 300MW+

• Different Steam Turbine configurations based on

heat demand

• Back-pressure

• Condensing with Steam Extraction

• kW to hundreds of MW

• Gas Engines have 2 waste heat streams

• High temperature exhaust gases

• Low temperature cooling circuits

• kW to ≈ 17MW



2014-11-20Page 10


Power Output, Heat to Power Ratio and the Type of Heat

will all have an impact on the optimum technology choice

• Technical and economic limitations on power output may apply

to some technologies

• Both at higher and lower ends of scale

• Electrical efficiency impacts on amount of heat recoverable

• Higher electrical efficiency, less waste heat

• Temperature of Waste Heat will affect type and amount of

process heat recoverable

• e.g. Steam requires high temperature waste heat

• High Electrical Efficiency does not necessarily mean high

overall energy efficiency



2014-11-20Page 11


Heat to Power Ratio

1.0

0.5

2.0

3.0

4.0

6.0

5.0

Gas Engine

Gas Turbine

Gas Turbine

with

supplementary

fired WHRU

Steam Turbine

Heat to Power Ratio

Total Efficiency of Gas Turbine and Reciprocating Engine

vs. Power / Heat Output

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 1.5

Thermal / Electric Power Ratio

To

tal E

ffic

ien

cy

, H

ea

t a

nd

Po

we

r

SGT-500 + WHRU

Reciprocating Engine +

WHRU



2014-11-20Page 12


Using Supplementary Firing of GT exhaust gases to boost Heat to Power Ratio

Duct Burner

(Optional)

Gas Turbine Generator

Fuel Gas

HRSG

Boiler Feed

Water

Process

Steam

Exhaust

Stack

0

25

50

75

100

125

150

175

200

0 5 10 15 20 25 30 35 40 45 50

Power (MWe)

Ste

am

(to

nn

es/h

r) [

12 b

ar

satu

rate

d]

Unfired

Fired

SG

T-1

00

SG

T-3

00

SG

T-4

00

SG

T-5

00

SG

T-6

00

SG

T-7

00

SG

T-8

00

• Supplementary Firing can

double steam (heat) production

Fuel Gas

Boiler fired to 850 deg C



2014-11-20Page 13


Type of Process Heat required

• Low Temperature Hot Water (LTHW)

• Very high overall energy efficiencies as can

recover waste heat from low temperature cooling

circuits

• High Temperature Hot Water (HTHW)

• Needs higher temperature waste heat, so in some

cases not able to use all waste heat sources

• Steam

• Needs high temperature heat source, the higher

the steam pressure required, the higher the waste

heat temperature needs to be

• Hot Air

• Depends on application: Direct/Indirect Drying or

Space Heating

Gas

Engine

Gas

Turbine

Steam

Turbine

LTHW

HTHW

Steam

Hot Air



2014-11-20Page 14


Selecting the correct technology for the specific application can

lead to very high overall energy efficiencies

• LTHW Hot water > 90%

• Steam > 75%

• > 85% with supplementary firing

• Hot Air > 90%

• High energy efficiency

= lower fuel consumption

= lower fuel bills

= fewer emissions

= environmental benefits

Supplementary

firing to 815 C

(process gas)

29 bar

process

steam

Economizer cooled

by DH water

Net power output: 14.9 MW

Process steam: 29 bar / 13.9 kg/s / 35.2 MJ/s

District heat duty: 13.6 MJ/s

Fuel efficiency: 71 %/ 90%

Dr. Ing. Pentru Ruset/.Energy Management Division


2014-11-20Page 15


Or the correct combination of technologies !

Supplementary HRSG

firing from 545 to

740 C (All HRSG)

Air-cooled DH auxiliary

cooler allows

independent

Power generation

Heat-only boiler

for DH peaks

Multiple gas turbines for

extended load range

and part load efficiency

I-91

Customer:

Latvenergo Riga TPP1, Latvia

Business Concept: EPC / Power Plant

In operation: Oct 2005

Net power output: 140 MW

District heating duty: 140 MW

Fuel efficiency: 91%



2014-11-20Page 16

Alternative Fuel Options

If Natural Gas is unavailable, other fuels can be utilized in

many technologies as the primary fuel or back-up fuel

• Diesel and high quality distillate fuels

• LPG, NGLs, Condensates and Naphtha

• Intermediate and Heavy Fuel Oils

• Crude Oil

• Biogases

• Digester (sewage) gas

• Landfill gas

• Process Off-Gases

• Refinery Gases

• Coke Oven Gas

• Blast Furnace Gas

MJW/ E P GT ST&P BD


2014-11-20Page 17

Conclusions

Cogeneration

• The most efficient way to meet local power and

heat demand

• Offers Economic benefits

• Offers local and global Environmental benefits

• Especially on Natural Gas Fuel

• Multiple technologies available to all optimum

plant design



2014-11-20Page 18

Thank you for your attention

Contact page

Dr. Ing. Petru Ruset

Country Division Lead Energy Management

Siemens srl

Bd. Preciziei 24; Complex West Gate Park

Cladirea CPSA; RO-062204; sector 1; Bucuresti

Romania

Phone: +40216296490

Mobile: +40744790527

E-mail:

[email protected]

siemens.com/answers

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Cogeneration: Energy Production maximising Efficiency and minimising Environmental ... · 2014-12-04 · Cogeneration: Energy Production maximising Efficiency and ... Total Efficiency