module 2c - casindo · module 2c anaerobic digestion ... opbrengst p y dm om m (in m3gas) m: ......

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Module 2c

Anaerobic digestion

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Training course on Renewable Energy

Outline

Process

Conditions

Biogas yield

Upgrading to Green Gas

Examples

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Anaerobic digestion

Proven technology from a very small scale (some m3reactor volume), to a very large scale (1000+ m3reactor volume)

Anaerobic digestion is– biological– degradation– of organic material– without oxygen present

resulting in a combustible gas, containing ca. 60%methane

Technology is suitable for “wet” biomass, such asmanure. Products are generally energy, heat andfertilisers

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The process

Biological steps– Hydrolysis: Break-down to smaller molecules– Acidogenesis: further break-down to e.g. acids– Acetagenesis: production of acetates, carbondioxide and hydrogen.– Methanogenesis: methane, carbondioxide and water are produced– There are several groups of bacteria that perform each step

Process conditionsRegimes Typical temperatures Typical residence timesPsychrofilic 15 – 22°C monthsMesophilic 25 – 38°C 25 – 50 daysThermophilic 50 – 70°C 10 – 30 days

The mesophilic regime is mostly used, because it is a stableprocess, producing a reasonable amount of biogas, in anacceptable time frame

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The process: no oxygen

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The process

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Flowsheet

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Larger scale Anaerobic Digestion

Silo

Insulation

Biogasstorage

Heating

Mixing

Covering

Manure input

Biogas to CHP unit

Regime: MesophilicResidence time: ca. 40 daysWorld-wide implementations: Several thousands (e.g. 1500 in Germany)

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Small scale digestor

Used for cooking or heating

Fed with manure (e.g. from cows,pigs, etc). Amount needed:>22 kg/day, which is 1 cow or 6pigs

Total costs ca. 100 - 150 USD

Applied in:• Costa Rica• Equador• Nepal (other design for cold climate)

>65,000 units implemented today

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Process conditions

Anaerobic conditions

>50 % moisture

Temperature (dependent on the type of bacteria)

Residence time

pH-value 7,5

Organic load ( OM/m3/day)

Additives (nitrogen, minerals)

Particle size substrate

Ammoniak formation (NH3)

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Biogas composition

<< 1Hydrogensulfide [H2S]

<< 1Oxygen [O2]

<< 1Hydrogen [H2]

<< 1Nitrogen [N2]

24 – 45Carbondioxide [CO2]

45 – 75Methane [CH4]

Volume percentage [%]Compound

HHVbiogas: 20 – 25 MJ/m3

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Energy production

Manure

Organics

Organics to biogas

Biogas

CHP (purpose build gas

engine)

Contains e.g. 10% solids (cow manure)Other components are water, dissolvedorganics and minerals

2/3 of solids material

0.4 m3/kg Organics (ca. 50% conversion)

60% methane, 40% CO2/ 21 MJ/m3

biogas

30% electrical energy and 50% thermalenergy (for example)

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Parameters:

DM [%]: percentage droge stof in substraat

OM [%]: percentage organische materie in substraat

ODM [%]: percentage organische droge stof (= DM . OM)

Y: Maximaal mogelijke productie biogas ( m3/(t ODM))

)gasm3(inmOMDMYPOpbrengst

m: massa substraat(t)

Source: bioenergy systems

Biogas yield

5124 – 88350 – 55070 – 8010 – 20Chicken

277 – 61350 – 55065 – 853 – 13Pig manure

259 – 51200 – 40065 – 857 – 15Cow manure

PgemPYOM(% van DM)DMSubstrate

5124 – 88350 – 55070 – 8010 – 20Chicken

277 – 61350 – 55065 – 853 – 13Pig manure

259 – 51200 – 40065 – 857 – 15Cow manure

PgemPYOM(% van DM)DMSubstrate

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Biogas yield

Manure type DS % m3/ton kWhel/ton

Pigs 9% 27 48

Cows 10% 14 26

Chickens 25% 82 147

Verge grass 30% 120 216

Maize 30% 150 270

Fats 100% 560 1000

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Application

Manure

Sludge (volume reduction)

Co-digestion (increasing gas yield

No woody materials:

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Upgrading to Green Gas orSynthetic natural gas

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History 1980’s: several initiatives (technical problems)

June 2004: co-digestion acceptance gave a boost in new projects

Biogas upgrading Pressure increase

H2S removal

CFK’s removal

CO2 removal

Drying

Smell

Quality and quantity control

Upgrading to Green Gas orSynthetic natural gas

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Biogas upgrading systems Membranes

Waster washing (absorption under pressure)

VPSA (adsorption with molecular sieves)

LP Cooab (chemical absorption)

Advantages/disadvantages of upgradingsystems Well-known and documented

Can be supplied if of interest

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Biogas upgrading VPSA, landfil gas, 1989(example)

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Active players in Netherlands Cirmac International

GTS, Gastreatment Services BV

BioGast Sustainable Energy

ENECO, Ecogas project

Sweden 30 biogas upgrading systems of which:

4 are delivering to the gasnet

26 are used for transportation fuel

Switzerland 6 upgrading plants delivering to the grid

2 more are under construction

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Constraints (according to Cirmac) No national quality requirements and analyses

prescription

No obligation for the distributor to accept Green Gas

Investment costs for piping, measures to be taken

No incentive for increased efficiency or lower emission

No consistent government policy

More chances by (according to BioGast) Introducing certificate system

Obliged percentage Green Gas in f.i. 2010

Level playing field for gas and electricity

No government interference with technology

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GPP® system (Gastreatment Power Package) Compression to 10 barg

TCR technology for gascleaning and cooling to minus 25oC

SOXSIA catalyst for H2S, siloxans and water removal

Cooling to minus 80 oC to condens the CO2

Results in wobbe index of 43,7 MJ/Nm3

Pilot plant of 30 Nm3/hr biogas Max. 16 Nm3/hr SNG

Liquid CO2 amounts to 18 kg/h

Electricity consumption is 12 kWe

Four test locations

Results so far are very promising

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BioGast Operational since September 2006

Private company producing Green Gas

Stand-alone units at biogas production location

Network of small units

Many advantages to CHP

“Gas is a fuel, electricity is energy”

Potential Now: Sewage sludge and landfills: 50-100 million m3 SNG

Within 10 years: >> 1000 million m3 SNG

Natural gas supply is limited and uncertain

Can be applied at each location

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Ecogas project (ENECO) Requirements to the biogas feed

Need for second Wobbe Index meter?

Reliability Sulphur measurement?

Allowable fluctuation of the Wobbe Index?

Whole list of paramaters and values

Injection of 75 m3/h biogas on the 100 mbar distributionnetwork

Safety requirements are slightly increased

Adjustments took much more time and more money!

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Situation is crucial (heat demand or not?)

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Potential study of biogas in the Netherlands, (report ofJanuary 2007, SenterNovem) 11% of natural gas can be replaced by SNG

Certification is needed like green electricity

Quality ensurance is needed

Arrangements of green gas injection to low pressure grid is needed

Financial support or fiscal measures is needed

Netherlands Platform New gas (PNG)

Within PNG: working group “Green Gas”

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Letter by Minister of Economic Affairs to theparliamant (26 March 2007): Green gas can contribute to sustainable development and

solving the manure disposal problems

The technology need to be further improved (digestion,gasification and upgrading to SNG)

The question: is Green Gas sustainable need to be answered

UKR (Unieke Kansen Regeling) can be applied, not the MEP(meant for green electricity only)

Before summer 2007 (to be expected)

Document “Visions on Green Gas” by SenterNovem

Respons from the parliament (priority statements by 2020)

Meeting of Dutch partners within Redubar with SenterNovem

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Examples in the Netherlands

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Example: Ukrain

THANKS FOR YOUR ATTENTION

TERIMAH KASIH

module 2c - casindo · module 2c anaerobic digestion ... opbrengst p y dm om m (in m3gas) m: ......

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