Workshop Energy Crops & Biogas Workshop Energy Crops & Biogas – – Pathways to Success, Pathways to Success, Cropgen/IEA Bioenergy, 22.9.2005 Utrecht, The Netherlands Cropgen/IEA Bioenergy, 22.9.2005 Utrecht, The Netherlands Biogas from Energy Crops Biogas from Energy Crops – – Preliminary Results of Biomass Storage and Preliminary Results of Biomass Storage and Pre Pre - - treatment under Northern Conditions treatment under Northern Conditions Jukka Rintala, Jukka Rintala, Annimari Lehtomäki, Outi Ronkainen, Annimari Lehtomäki, Outi Ronkainen, University of Jyväskylä, Finland University of Jyväskylä, Finland
Transcript
Workshop Energy Crops & Biogas Workshop Energy Crops & Biogas –– Pathways to Success, Pathways to Success, Cropgen/IEA Bioenergy, 22.9.2005 Utrecht, The NetherlandsCropgen/IEA Bioenergy, 22.9.2005 Utrecht, The Netherlands
Biogas from Energy Crops Biogas from Energy Crops ––Preliminary Results of Biomass Storage and Preliminary Results of Biomass Storage and
PrePre--treatment under Northern Conditionstreatment under Northern ConditionsJukka Rintala,Jukka Rintala, Annimari Lehtomäki, Outi Ronkainen, Annimari Lehtomäki, Outi Ronkainen,
University of Jyväskylä, Finland University of Jyväskylä, Finland
Methane from Energy CropsSelection of Crops
HarvestingSize Reduction
Pre-Treatment (1)
Storage- Ensiling
- Dry Storage
BiogasProduction
Storageof Digestate &
Post Gasification
CropCultivation
Pre-Treatment
(2)
Methane
Digestate
HeatElectricity
Traffic Fuel
Post-Treatment
Harvest Time
Reasons for PreReasons for Pre--storing Biomass storing Biomass for Biogas Productionfor Biogas Production
Short cultivation periods, storage needed up Short cultivation periods, storage needed up to 8 monthsto 8 months
Optimal methane yields per hectare with Optimal methane yields per hectare with several harvesting times (methane yield / several harvesting times (methane yield / VS, biomass production per hectare)VS, biomass production per hectare)
Energy produced when most optimum / Energy produced when most optimum / needed needed
Methods for PreMethods for Pre--storing Biomassstoring Biomass
Aiming at low CHAiming at low CH44 potential losses (VS losses (nonpotential losses (VS losses (non--structural carbohydrates ))structural carbohydrates ))Storage as a preStorage as a pre--treatment: improving methane yields treatment: improving methane yields and methane production ratesand methane production ratesSimple and low cost techniques and management Simple and low cost techniques and management Potentially different options (scale) for Potentially different options (scale) for –– farmfarm--scale vs. centralised digesters scale vs. centralised digesters –– coco--digesting vs. crop digesting plants digesting vs. crop digesting plants –– dry vs. wet processesdry vs. wet processes
PostPost--storing Digested Biomass storing Digested Biomass for Biogas Productionfor Biogas Production
Reasons for (covered) postReasons for (covered) post--storing digested biomass storing digested biomass –– Only short periods (3Only short periods (3--4 months) potential for land application 4 months) potential for land application –– No other use for the digestate than land applicationNo other use for the digestate than land application–– Recovery of remaining methane potential, prevent methane Recovery of remaining methane potential, prevent methane
Up to 8Up to 8--9 months, sufficient capacity9 months, sufficient capacitySimple and low cost structures at ambient temperaturesSimple and low cost structures at ambient temperaturesStimulate methane recovery:Stimulate methane recovery:
PostPost--treatment before posttreatment before post--storagestorageLow cost passive heating systems to increase temperatureLow cost passive heating systems to increase temperature
Different options for farmDifferent options for farm--scale vs. centralised digesters and for scale vs. centralised digesters and for coco--digesting vs. crop digesting plants digesting vs. crop digesting plants
Storage of Crop BiomassStorage of Crop Biomass
Traditional methods: drying, ensilingDrying � High losses of organic matter, subjectivity to weather conditions,
dry material not suitable for biogas production
Ensiling: soluble carbohydrates contained in plant matter undergo lactic acid fermentation:→ pH drop → Inhibition of growth of detrimental micro-organisms
The process can be controlled by Preventing the growth of all micro-organisms (e.g. acids) Stimulating the growth of lactic acid bacteria (e.g. bacterial inoculum or enzymes)
Storage trialsStorage trials
Storage of timothyStorage of timothy--clover clover grass and rye grass as grass and rye grass as silage in bales for 3silage in bales for 3--8 8 months in field conditions months in field conditions with and without additiveswith and without additivesSystematic followSystematic follow--up of the up of the chemical characteristics, CHchemical characteristics, CH44potential and mass potential and mass Finally, after 6Finally, after 6--8 month 8 month storage costorage co--digested with digested with manure in farm digestermanure in farm digester
StoringStoring –– laboratorylaboratory studiesstudiesGrass (75 % timothy Phleum pratense, 25 % meadow fescue Festuca Pratensis), 30 % TS, VS/TS 0,9, lignin 15 % of TS, 0.23 m3CH4/kgVS, 64.2 m3CH4/tFWStored in 5 L laboratory silos for 3 months at 20oC, and for 6 months at 20 and 5 oC without and with additives:– Formic acid – Enzymes
- Xylanases and cellulases– Lactic acid bacteria
- Lactobacillus rhamsonus and Propionibacterium freudenreichii– Mixed culture from a farm biogas reactor
0.0
0.1
0.2
0.3
0.4
No additive Formic acid Enzyme Lactic acidbacteria
Mixed culture
Spe
cific
CH
4 yi
eld
(m3
/ kg
VS
orig
inal
)
Fresh crop After addition of storage additiveAfter 3 months at 20oC After 6 months at 20oCAfter 6 months at 5oC
Storage without additives led to losses of 17-39 % in methane potential.
Most additives increased the initial methane yields (partially acting as substrate) and decreased the methane potential losses during storage.
Without additives storage time (3-6 months) and temperature (5 -20°C) had major impacts on methane potential, but not with additives.
PrePre-- /Post /Post --treatment of Energy treatment of Energy CropsCrops
Objectives:Increase methane yields or / and methane production rates:
in biogas digesters: 35°C, HRT 20-40 daysduring post-storage/methanation (several months at 5-20°C)
Impacts:Increasing available surface area for microbial action Breaking polymeric chains to more easily accessible soluble compounds� Promoting subsequent biodegradation
Alkali treatments (NaOH, Ca(OH)Alkali treatments (NaOH, Ca(OH)2 2 +Na+Na22COCO33))–– 15 % increase in CH15 % increase in CH44 yieldsyields
Physical, biological, peracetic acid Physical, biological, peracetic acid treatmenttreatment–– High losses of organic matterHigh losses of organic matter–– No increase in methane yieldNo increase in methane yield
PublicationsPublicationsLehtomäki, A., Ronkainen, O. & Rintala, J. 2005: Developing storLehtomäki, A., Ronkainen, O. & Rintala, J. 2005: Developing storage methods for age methods for optimised methane production from energy crops in northern condioptimised methane production from energy crops in northern conditions. Proc. 4th tions. Proc. 4th International Symposium on Anaerobic Digestion of Solid Waste, 3International Symposium on Anaerobic Digestion of Solid Waste, 31.8.1.8.--2.9.2005, 2.9.2005, Copenhagen, Denmark, p. 101Copenhagen, Denmark, p. 101--108.108.Lehtomäki, A., Ronkainen, O., Viinikainen, T., Alen, R. & RintalLehtomäki, A., Ronkainen, O., Viinikainen, T., Alen, R. & Rintala, J. 2005: Factors a, J. 2005: Factors affecting methane production from energy crops and crop residuesaffecting methane production from energy crops and crop residues. Proc. 8th Latin . Proc. 8th Latin American Workshop and Symposium on Anaerobic Digestion, 2.American Workshop and Symposium on Anaerobic Digestion, 2.--5.10.2005, Punta 5.10.2005, Punta del Este, Uruguay.del Este, Uruguay.Lehtomäki, A., Viinikainen, T. A., Ronkainen, O. M., Alen, R. & Lehtomäki, A., Viinikainen, T. A., Ronkainen, O. M., Alen, R. & Rintala, J. A. 2004: Rintala, J. A. 2004: Effect of preEffect of pre--treatments on methane production potential of energy crops and ctreatments on methane production potential of energy crops and crop rop residues. Proc.10th World Congress on Anaerobic Digestion, 29.8.residues. Proc.10th World Congress on Anaerobic Digestion, 29.8.--2.9.2004, 2.9.2004, Montreal, Canada, p. 1016Montreal, Canada, p. 1016--1021.1021.Lehtomäki, A., Viinikainen, T., Alen, R. & Rintala, J. 2003: MetLehtomäki, A., Viinikainen, T., Alen, R. & Rintala, J. 2003: Methane production from hane production from energy crops and crop residues: Effect of harvest time and chemienergy crops and crop residues: Effect of harvest time and chemical composition. cal composition. Proc.IntProc.Int. Nordic Bioenergy Conference, 2. Nordic Bioenergy Conference, 2--5 September 2003, Jyväskylä, Finland, 5 September 2003, Jyväskylä, Finland, p.198p.198--200.200.Lehtomäki, A., Viinikainen, T. & Rintala, J. (submitted): ScreenLehtomäki, A., Viinikainen, T. & Rintala, J. (submitted): Screening boreal energy ing boreal energy crops and crop residues for methane biofuel production.crops and crop residues for methane biofuel production.Viinikainen, T., Lehtomäki, A., Ronkainen, O. & Rintala, J. (in Viinikainen, T., Lehtomäki, A., Ronkainen, O. & Rintala, J. (in prep.): Effect of prep.): Effect of chemical prechemical pre--treatments on anaerobic digestion of energy crops and crop residtreatments on anaerobic digestion of energy crops and crop residues.ues.
