Biogas from energy crops and biowastes Other/Oth_37_Helsinki_Ban… · Charles Banks University of...
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EUROPEAN CONFERENCE on BIOREFINERY RESEARCH Helsinki, 19 and 20 October 2006 Biogas from energy crops and biowastes Charles Banks University of Southampton
Transcript of Biogas from energy crops and biowastes Other/Oth_37_Helsinki_Ban… · Charles Banks University of...
EUROPEAN CONFERENCE on BIOREFINERY RESEARCHHelsinki, 19 and 20 October 2006
Biogas from energy crops and biowastes
Charles BanksUniversity of Southampton
Old technology - new application
The technology of biochemical methane generation is well establishedTraditionally it has been used for waste stabilizationCurrent focus is on energy production To be cost-effective in this role may require ● engineering and technical improvements to increase conversion
efficiencies● Selection and production of biomass feedstocks from a variety of
sources • including novel and multi-use crops and agro-wastes from integrated
farming systems, commercial and industrial wastes and by-products.
BIODEGRADABLE ORGANIC MATERIAL(CARBOHYDRATES, FATS, PROTEINS)
HYDROLYSIS SIMPLE SOLUBLE ORGANICS
ACID FERMENTATIONPROPIONIC ACIDBUTYRIC ACIDLONG CHAIN VFA
ACETIC ACID
ACETOGENESIS H2 + CO2ACETIC ACID
ACETOCLASTIC METHANOGENIC
BACTERIA
HYDROGEN-USING METHANOGENIC
BACTERIA
CH4 + CO2
METHANOGENESIS
Anaerobic digestion in its simplest form
Closed reactorSystem of gas collectionProduction of biogasProduction of digestate Anaerobic
reactor
Gas storage
Energy
Heat
Energy use
excess
Product
Product use
Fibre compost
Product and Energy use
Storage and pretreatment
DIGESTER
Digestate separator
Liquor
Fibre (straight to land)
Vehicle engine
Transport
CHP
Electricity
Process heat Space heatHot water
Gas engine turbine
Gas burner or boiler
Biogas storage
Biogas cleaning
BIOMASS and AGRO-WASTE
Hydrogen reformation for fuel cell applications
Process types
Wet
Thermophilic
One stage Multi-stage
Dry
Mesophilic
Process differences
Wet Process Dry Process• less than 15 % feedstock
solids concentration• one or several stages• usually operate at 35oC• requires water addition
or recycle• larger reactor • proven technology for
sewage sludge digestion• more applicable to co-
digestion with other waste
• more than 15% feedstock solids concentration
• usually one stage• can operate at 35oC or 55oC
• minimal water addition• smaller reactor• becoming most popularchoice for MSW
• more data and referenceplants needed
Wet digesterDry digester
mesophilic
thermophilic
Dry digester
Instantly recognisable!
Biogas as a renewable energy source
Local and national
analysis boundary
energy crops and crop residues
digestate
gas
FYM & slurry
residues
Anaerobic digester
Crop and animal
production
Processing plantproduct
Heat and power
Transport fuel
Local housing, industry, commercetransport
transport
Fuel, fertilizers, equipment CO2
CO2
CO2
waste
CO2
transport
analysis boundary
analysis boundary
Database of energy inputs into the cultivation of different crop types establishedFactors affecting energy use in the process have been identifiedEquations developed to account for energy usage in the digestion processEnergy usage model developed based on typical anaerobic digestion plant configurations and substrates
Energy models
Phase separation innovations
Single stage
Two stage
Permeating bed
UASB or AF
Plug flow
Uncoupling of solids and liquid retention time
Hydrolysis and
acidification reactor
Methanogenicreactor
Two phase systems(coupled and uncoupled)
Permeating beds
Plug flow reactors
Permeating bed reactors
● Single bed systems using grass and maize have given poor results even with pH control
● Permeating bed with second stage high rate methanogenicreactors gives greater potential for stable operation and biogas production
● May be some potential for certain crop types but preliminary results indicate that overall process efficiency is likely to be poorer than for single phase mixed reactors
● Potentially an interesting mix of fermentation products
Plug flow systems
● Result from a high initial loading in the reactor
● Plug flow may limit the overall loading that can be achieved
● Interesting gas and acid production profile (H2)
● May have potential for certain waste types and concept could be further exploited for refined fuel production and biorefineryintermediates
● Still to explore very high solids systems with high recycle rates
R2 VFA profile and gas productionDay 1
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Two phase systems
● Overall performance for the treatment of market wastes at thermophilic temperatures and the loading used shows no advantage in process stability or performance compared to single phase controls
● Uncoupling of solids and liquids retention time in a first phase mixed reactor using maize as a substrate failed to improve rates of hydrolysis and solids destruction
Digester VFA
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Digester alkalinity
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Acknowledgements - Current project
Acronym: CROPGENTitle: Renewable energy from crops and
agrowastesContract: SES6-CT-2004-502824
Duration: 1 March 2004 – 28 February 2007Total cost: 2.5 M€ EC funding: 2.1 M€website: www.cropgen.soton.ac.uk
