Manure, the sustainable fuel for the farm - BioEnergyFarm 2 · Manure, the sustainable fuel for the...

Manure, the sustainable fuel

for the farm

Workshop name

Venue, dd month yyyy

Speaker‟s name

Workshop content

• Introduction

• Project planning

• Project implementation

• Biogas plant operation

• Economy

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Introduction

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Small scale Biogas Plants in …

(Remark: Please insert data or graph related

to the biogas market in your country)

Incentives for the implementation of

small scale biogas plants:

4

• Governmental Goals

• Emmission trading certificates

• Renewable Energy Law

• Subsidies

• Personal incentives: energy

independancy, additional income

Biogas Technology

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Process conditions:

- Under exclusion of air (anaerobic)

- Moisture (max. 20 % DM in wet digestion)

- Heat: 35°C – 45°C (often), 50°C – 55 °C (rare)

- Neutral to slightly alcaline pH-value

Microbial(Biological)Process

(wet) Biomass

Solid, liquid manure, org. residues, energycrops

Digested substrate

Nutrients

Biogas (CH4, CO2)

The Digestion Process

• Well-known feedstock;

• Potentially available in significant quantities;

• Good for co-digestion with other feedstock

such as food waste;

• Economically feasible only if biogas digester

is located at the place of manure production:

• transportation of manure is costly

• manure has relatively low-biogas yields.

Manure

Characteristics of Liquid Manure Collection

Daily fresh supply is important!

Manure store for longer periods of time (due to slatted/

perforated floors and manure cellar) decreases

specific gas yield

Preferable:

Stables with external manure storage

A manure system based on scrapers

Usage of daily fresh manure

Additional benefit: hygienic advantages on the stable

atmosphere due to a reduction of harmful gases from

the manure

Characteristics for Solid Manure Collection

10/30

Quantity and quality of material removed from outdoor

feedlots is influenced by uncontrollable climatic

conditions

Significant soil is removed during cleaning which leads

to high ash content in the manure

Dry matter content of harvested manure averaged

75% as compared to the original excreted manure that

is approximately 10%.

Ash content of harvested manure is approximately

66% as compared to a 20% ash content in excreted

manure

Organic matter content: 25-30% (50-80% excreted

manure)

CosubstratesOld breadApple pomaceSpent grains / daffBiowaste (households)Grease trapFlotation fatFrying fatVegetable residuesGrain sweepingsCerial mashGlycerineCoffee draffCacao shellsPotatoe leafsPotatoe peelsPotatoe mashLeafsMolassesWheyFruit pomaceRape meal extractColza cakeLawn cuttingsCanteen / Catering WasteOnion peels……

Organic Residues

Corn Cob MixEnsiled fodder peasEnsiled fodder beetsCereal mashCereal strawGrass silageRye total plant silageOat silagePotatoesPotatoe mashClover grass silageAlfalfa silageCorn seedsCorn silageRape seedsRye grainsRed clover silageEnsiled beets (in general)Sun flower total plant silageTriticale total plant silageTriticale grainWheat total plant silageWheat grainsEnsiled sugar beets…..

Energy Crops

1

Source: Handreichung Biogasgewinnung und –nutzung, Fachagentur Nachwachsende Rohstoffe e. V.

Landfill gas5%

Sewage sludge11%

org. Residues7%

Slurry and Manure / Dung

27%

Agricultural by-product

25%

Material from land

conservation activities

3%

Energy crops22%

Share of different digestible organic mass

flow related to the total potential

The Gas

CvHwOxNySz

Organic Substance

Bacteria

Heat

Biogas: (composition)

CH4: 45 – 70 Vol-%

CO2: 25 – 50 Vol-%

O2: 0 – 3 Vol-%

N2: 0 – 5 Vol-%

H2O: 0 – 10 Vol-%

H2, NH3, H2S in ppm-level

1 m³Biogas

= 0,6 Liter Fuel Oil(with 60 Vol-% CH4)

Digestor Types

Completely mixed reactor (standing): Slurry storage made of concrete or steel, mixedand heated, can come in differnt hights andwidths

Plug flow reactor (horizontal): Steel

or concrete tank with paddle stirrer, heated

Biogas plants are operated in different ways:

Overflow system

communicating vessels

• Through hydrostatic pressure, liquid level is

at the same height in the connecting pipe

• Liquid levels balance themselves

• Overflow works

Functional principle

The Conversion process

Process heat

to digester

Biogas

Electric energy Thermal energy

Energy for use

Energy conversion

(CHP, Fuel cell)

Vorgrube

Kondensat-abscheider

Feststoffeintrag

Basic Components of a small scale

Biogas Plant

Rührkessel-reaktor Endlager

Überschusswärme

HeizöltanksBHKW

Further plant components which could be necessary for

the digestion of organic residues and energy crops:

• Reception bunker or –pit

• Crushing technology

• Separation of impurities

• Hygienisation unit

• Hydrolysis tank

• Dosing unit

Advantages & Aims of Biogas

Technology

1. Energy– Production of gas, heat and

power

2. Ferilizer value– Avoidance of nutrient losses

– Reduction of plant corrosion

– Improvment of fluidity

– Improvment of plant

compatibility

– Improvment of plant health

– Reduction of germination

capacity of weed seeds

3. Environmental Compati-

bility– Reduction of odour

– Reduction of methane and

ammonia emissions

– Reduction of nitrate leaching

– Hygiensiation

– Recycling of organic residues

– Avoidance of sewer connection

in remote areas

Feedstock & Microbiology

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Biogas formation

• Biogas is formed by microorgani-

sms that degrade organic material

under anaerobic conditions

• Naturally occurs e.g. in

landfills, bogs & mires, manure

storage tanks

• Complex & interdependent process

that happens in several stages

Feedstock for Biogas plants

www.de.wikipedia.org www.duden.de

www.de.wikipedia.org www.fraunhofer-umsicht.de

IBBK Fachgruppe Biogas GmbH

Organic matter – feedstock for

microorganisms

• Feedstock (fresh

matter) consits of:

water + dry matter

Volatile solids [from % FM or % DM ]

Mineral solids (ash)

Water content

Dry

matt

er

(DM

)

Fre

sh

matt

er

(FM

)

• Microbes “eat”

volatile solids

(= VS),

The 4 Steps of Biogas Formation1. Step

Hydrolysis2. Step

Acidogenesis3. Step

Acetogenesis4. Step

Methanogenesis

hydrolyticBacteria

acidogeneticBacteria

acetogenicBacteria

methanogeneticBacteria

Fatty acids(Propionic acid)

Alkohols

BiomassPolysacharids

ProteinsFats

SugarsAminoacidsFatty acids

BiogasCH4/CO2

H2/CO2

Acetic acidH2

one-stage

process

biogas digestate

The different degradation processes ...

• … occur at the same time simultaneously

In agricultural biogas plants the separation of the

degradation stages plays a minor role

• … strongly depend on each other

Intermediate products are needed for following processes

• … can cause mutual inhibition

▪ Intermediate products may not accumulate

▪ Product inhibition

• … develop slowly in advanced stages

Hydrolysis is the fastest, methane formation

the slowest

Odour reduction of animal slurry

through digestionR

ela

tive c

oncentr

ation [%

] x

Retention time [days]

An import basic substrate for biogas

production: manureMean values of few raw manure and digestate samples

of “Biogas plant Oberlungwitz”

Raw manure Digestate

DM [%] Nitrogen Ammonium Phospho-

rous

Potash Magnesium Calcium pH-value

Temperature ranges

• Psychrophil (< 25 °C)

low growth rate long retention times

inefficient for biogas production no longer in use

• Mesophil (32 - 45 °C)

stable biocoenosis satisfying gas yield with acceptable retention time

common, particularly in wet fermentation processes

• Thermophil (50 - 60 °C)

high gas yield after short retention time

sensitive biocoenosis caution with rapid degradable substrates,

(hydrolysis develops too fast)

Project planning 1 – Process

parameters

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Dry matter contents

Dry matter (DM):

DM [%FM] = Measure unit for the sum of total solids in the substrat related to fresh mass

Volatile Solids (VS):

VS [%FM] = Measure unit for the sum of volatile solids in the substrat related to fresh mass

VS [%DM] = Share of the volatile solids in dry matter

• Biogas production only possible from VS!

• Important: determination of degradable part of VS

(Hydraulic) Retention time t, HRT

[days]x

d

m³Input SubstrateDaily

[m³] VolumeWorking[d]HRT

Working Volume = Usefull reactor volume

• central planning parameter with manure plants

• less important parameter with energy crops or waste

6

Retention time of solid feedstock

m³

tContent DigesterDensity

[t]feestock solid of Tonnage[m³]Input

Density Digester Content ≈ 1 t/m³

• Solid feedstock is added by tonnage

converstion to volume needed:

6

Example:

daily manure input: 5 t/Tag

Digestor – Working Volume: 300 m³

Gas space: 30 m³

d 54

³1

5

m³ 30 - 300 VZ

m

td

t

Recommended retention times with mesophilic temperatur in

digester: (depending on process and reactor)

min max

Liquid hen manure: 20 - 40 Days

Liquid pig manure: 22 - 50 Days

Liquid cow manure: 25 - 60 Days

Solid cow manure with straw: 40 - 90 Days

³][

)(

³BR

mumeworkingvol

dVSkgDayDrymatter

dm

oDMkg

• Dry Matter (DM, VS, CSB, TOC) - Load per m³ working volume

• Tendency for higher loading rate (Energy crops, Waste)

• Alternative: Digester load

- related to VS in Reactor (bacterial density)

- at the moment no relevance

8

Organic Loading Rate BR

Project planning 2 –

Feedstock

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Feedstock related biogas yields

Source: LFL

20

20

56

176

185

208

292

590

598

875

48

57

0 100 200 300 400 500 600 700 800 900 1000

Dairy slurry (8,5 % TS)

Pig slurry (6 % TS)

Poultry manure (15 % TS)

Total plant silage (38 % TS)

Corn silage ( 33 % TS)

Gras silage (40 % TS)

Weizenstroh (86 % TS)

Corn, dry (87 % TS)

Wheat grains (87 % TS)

Used oil & fat (95 % TS)

Kitchen waste (14 % TS)

Vegetable waste (15 % TS)

spez. Biogas yield [m³Bioas/tSubstrat]

Biogas yields from feedstock

Is determined by:• Ingredients of the

substrate

– Organic content (volatile solids / VS)

– Proportion of fat, protein and carbohydrates

• Retention time in digester

• Form of preparation

• Process temperature

Source: C. Tidjen, FAL

Methane production Maize

silage

Process time [d]

Organic constituentsGas yield [m3/kg]

Methane content [%]

Raw protein 0,7 71

Raw fat 1,25 66

Raw fiber 0,79 50

Free N extract materials 0,79 50

Source: Roediger

Detailed feedstock data

Remark: values are general, for exact valuesan individual substrate analysis has to be undertaken!

Manure

Energy crops and agricultural subproducts

Agroindustrial and slaughter house wastes

FeedstockDM

[% FS]oDM

[% FS]oDM

[% TS]Methane[Vol%]

m³CH4/t oTS

m³ Biogas/ t FM

Cow manure 8,5% 7% 85% 55% 280 20

Pig manure 6% 5% 85% 60% 400 20

Hen manure 15% 11% 75% 65% 500 56

Maize corn dry 87% 86% 98% 53% 690 590

Grass silage 40% 36% 89% 54% 584 208

Wheat corn 87% 85% 98% 53% 701 598

Maize silage 33% 32% 96% 52% 586 185

Wheat straw 86% 79% 92% 51% 369 291

Green grain silage 38% 35% 93% 53% 496 175

Vegetable waste 15% 11% 76% 56% 500 57

Kitchen waste 14% 11% 82% 60% 420 48

Old fat 95% 87% 92 % 68% 1000 45

Source: LFL

Operators‟ do‟s & dont‟s

• Do start slowly → give micro-organisms time to adapt

• Do provide stable conditions for your little co-workers:

– Regular feeding of same ration

– Maintain a constant temperature

• Do regular plant checks

– Keep a data log

• Don‟t be erratic & unreliable!

Project planning 3 – Biogas

plant components

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Planning and designing of

Components

Mixing pit:Storage time

Digester:Organic loading rate,Retention time,Substrate mixing

Substrate storage:Storage time

SolidsFeeder:Bunker size

CHP:Gas potential

Silo:

Required area,

Volume,

Storage time

• Storage capacity max. ca. 5 days

• Leachate of silo and percipitation (if possible)

• Possibilities of mixing-in co-substrates

• Not too big: Mixing energy

Solids feeder

• Storage capacity of min. 1 day

• Density of energy crops loose ca. 0,5 t/m³

• Avoid too long storage time: composting!

• Control of mass flow instead of time

Sizing of feeding systems

Mixing pit

Digester sizing

• Design according to hydraulic retention time (manure based plants)

– 50–60 days

• Design according to organic loading rate (energy crop and waste

plants)

• Loading rate will be higher with more energy crops

– Less manure BR = ca. 4 kg oTS/m³ d

– More manure BR = max. 2 kg oTS/m³ d

• Future plant extention should be included in planning

– First step lower organic load => bigger digester than needed

– Easier operation from the beginning

– After a successful learing time organic load can be increased

• Digestate storage requirement

• Consider mass loss through biogas process

– Very low with liquid manure (ca. 5 %)

– Relatively high with energy crops and wastes (ca. 25 %)

– Very high with corn of grain (ca. 75 %)

• Formula for design (6 months storage):

• Consider already available storage!

• Post digester = Storage volume

Necessary storage Vol.[m³] = (Substrate input[t] – Mass loss[t]) / 2

Sizing digestate storage tank

• Expected gas yield and expected methane contentBiogas [m³/a] * CH4-Cont. [%] = Methane yield [m³ CH4/a]

• Energy content methane: 10 kWh/m³Methane yield [m³ CH4/a] * 10 kWh/m³ = Brutto energy [kWh/a]

• Elektrical efficiency hel (30 – 40 %)Brutto energy [kWh/a] * hel = Elektrical Energy [kWh/a]

• Desired full load hours hfull = ca. 8.000 h/aElektr. Energy [kWh/a] / hfull [h/a] = theor. continous load [kW]

Sizing of CHP unit

Environmental & Social

benefits

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Environmental Benefits

Triple benefits for GHG-emission reduction:

48

1. Methane emission reduction through bettermanure management agricult. GHG ↓

2. Energy production from biogas (power, heat,

vehicle fuel) GHG from fossil fuels ↓

3. Better fertiliser value less need for mineral

fertiliser GHG from fertilser production ↓

Environmental Benefits

plus

49

4. Weed and pathogen control through AD

5. Phosphate recycling saves scarce P-

sources

6. Reduced odour emissions from animal

husbandry

Manure vs. Digestate

Advantages of digestate

• low in odour → appreciated by

population

• improved plant compatibility

• better flowability → easier soil penetration

• high share of NH4 → more effective, better

control of fertilising effect, reduced leaching

into ground water

50

Social Benefits

AD gives farms & rural areas new perspectives:

51

+ Additional income for farms (or reduced energy

costs, e.g. through self-supply in Belgium)

+ Local companies are involved in construction

of AD plants, maintenance and repair

Support of SME in rural areas

Strengthening of a regional financial circuit

• Decentral (renewable) energy production

diversification of energy supply

→ 50% of renewable energy plants are owned

by citizens (partly aiming at supplying

regional energy)

→ 754 energy cooperatives

→ 70 new public service companies since 2005

Social Benefits from renewables –

facts from Germany (status quo 2012)

52

Source: IÖW: Wertschöpfung durch Erneuerbare Energien, SR 210/15, Dez. 2015

• Direct national added value from renewables:

18.9 billion €

→ 12.5 billion € (= 66 %) remain on commu-

nal/ municipal level

→ 177.150 full-time jobs, 75 % in planning,

production & installation

Social Benefits from renewables –

facts from Germany (status quo 2012)

53

Source: IÖW: Wertschöpfung durch Erneuerbare Energien, SR 210/15, Dec. 2015

Main messages

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• Manure is available free of costs→ Additional income for farms

• AD is good for the environment→ 3-fold reduction of agriculture„s CO2-

footprint

• AD makes rural live more attractive→ Creates or keeps jobs in rural areas

→ Less smell from animal husbandry

55

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jegliche Verwendung der darin enthaltenen Informationen.