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Biogas, what’s in it for you? Overview of trace components Dr. Erik Polman

Kiwa Gas Technology Netherlands

May 12th, 2011, Copenhagen EGATEC2011

© Kiw a 2011 2

Contents

Difference between natural gas and biogas-biomethane Control of gas quality Trace components

Impact of trace components Legislation, standardization

Conclusions

© Kiw a 2011 3

Natural gas, biogas and biomethane

Natural gas: A gas, consisting of mainly methane, created from buried organic

material created at higer pressures and temperatures

Biogas Biogas is produced by anaerobic digestion or fermentation of

biodegradable materials

Biomethane Biogas upgraded to natural gas quality

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What’s the difference between natural gas and biogas? (1)

Natural gas Biogas-biomethane

Main composition C1 till C4 C1 and CO2 Traces Aromates, Hg, He,

mercury helium, CO2 , sulfides

Sulfides, ammonia, various other traces

Production Cleaned and upgraded to natural gas quality

Cleaned and upgraded to natural gas quality

Control Controlled and measured Controlled and measured

Injection Transport grid Mainly distribution grid Gas quality Arranged in mutual

agreements Arranged in mutual agreements

Reliability Reliable and safe Track record since 1988

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What’s the difference between biomethane and natural gas (2)?

There are some striking differences: The number of biomethane injection sites are small in size

but numerous Injection mainly in the distribution grid (low pressure) Compression to the transport grid or gas storages is possible

and arranged (e.g. Germany) Limited knowledge and experience for biomethane Composition: no C2, C3 etc in biomethane Trace components in biomethane

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How can we control the gas quality of biomethane before injection?

A gas station with a measuring unit and odorisation unit Responsibility: grid owner or producer (nationally agreed on) Deviating values: off spec → flare off or back to upgrading unit To be measured:

Methane, carbon dioxide, oxygen, nitrogen, water dew point Hydrogen sulfide Temperature, pressure, caloric value, Wobbe number

Regular control of trace components Price of a biomethane station: ± 100 k€

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Some trace components in raw biogas

Landfill gas Sewage sludge

Green waste

Manure Raw materials

H2S 100 ppm 40 ppm 500 ppm 2000 ppm 500 ppm

BTX 100 ppm 10 ppm - - -

Siloxanes 1 – 100 mg/m3

1 – 30 mg/m3

traces traces

traces

Ammonia traces traces traces up to 90 ppm

traces

Halogens 50 mg/m3 1 mg/m3 traces traces traces

Hydrogen 1000 ppm 1000 ppm 1000 ppm 1000 ppm 1000 ppm

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Siloxanes (1)

Used in products like soap and cosmetics Mainly founds in landfills especially “young” landfills Source: J.F. Pierce SCS Energy

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Siloxanes (2)

There are many types of siloxanes: lineair as well as cyclic Most common types: D4, D5, L2, L3

D5 L2

Risk of siloxanes: silica formation leading to blockage or erosion of micro turbines

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Siloxanes (3)

In practice no problems so far Potential risk for landfills and sewage sludge

No uniform method for detection Reference gases are not stable and vary for each laboratory

Proposed actions Determine and develop uniform method for detection Set a limit based on actual risks Regularly control of biomethane

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Hydrogen

Hydrogen is a byproduct of digestion The results of Naturalhy donot give evidence that 1000 ppm

will be a problem Additional “problems”: hydrogen is not measured by all GC’s

(custody transfer)

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Halogens

Occurence: Practically all combinations of C1 and C2 with chlorine and fluorine (tetra, chloroform, etc.)

Main problems in landfills: contaminations Compounds are toxic Levels in biogases (except landfills) are low (0,1 ppm)

Actions

Determine limit value based on risk Regularly control

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Oxygen

Sources-air: Excess at fermentation Rough desulphurisation Quality adjustment

Limits in national standards biomethane vary from 0,01% tot 3%

Problems may occur when gas is pressurized to the transport grid

Risk in gas storages: sulphur formation and consequently pore blocking

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Micro organisms (1)

Micro organisms (MO) are everywhere, also in natural gas

MO are related to biogas according to the public MO like humid conditions What MO can be harmful?

Pathogenic bacteria Methane oxidizing bacteria Sulphate reducing bacteria Iron oxidizing bacteria Archea (methane producing)

Methanopyrus Kandleri Source: Wikipedia

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Micro organisms (2)

Various studies carried from SGC (Sweden), GTI (USA) and E.ON Ruhrgas (Germany) : So far no indication for increased risks compared to natural gas

Gerg study: Proposal for broad R&D including influence of oxygen and humidity

and comparison with natural gas as a reference

Practice: Germany and Sweden: no specific measurements Netherlands: filter is obliged, control very six months

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Micro organisms (3)

Preventive measures: Treatment of biomass Heat treatment UV radiation Fine pore filtering

How to analyze: No standardized sampling procedure PCR analysis is generally accepted No criteria for acceptable level or species

Proposed actions:

Build up databank for MO in biogas, biomethane and natural gas Define uniform sampling and detection method Set up criteria

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Surprise effects: from green gas to orange gas

Olfactory of the odorant may be affected Example: corn digestion with biomass waste like oranges Limonene extracted from orange peels Smell of THT is eliminated: risk

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Legislation/standardization

National specifications in various countries European level:

TC 234 WG9 has worked on a technical report December 2010: M/475 invites to develop standards

- Inject ion of biomethane in the grid - Use as transport fuel

28th April 2011: - Decision taken on new TC 408: Biomethane for use in transport and

inject ion in natural gas pipelines

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Gaps in knowledge

Influence and impact of micro organisms Protocol for measuring MO Impact of silicon compounds

Determine specification

Detection method for determination of silicon compounds

Specification for halogen compounds Integration of biomethane from the distribution to the

transport grid with hands on effect on gas storages

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Conclusions

Type and level of contaminants depend on biomass Make proper risk analysis

With modern technology almost everything can be removed

Going from low to high pressure may cause new problems and challenges for the gas chain

Some gaps in knowledge need to be handled before preparing European standards

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Thank you for your attention

George Bernanos (1888-1948): "On ne subit pas l'avenir, on le fait." One doesnot undergo the future, one makes it!