1 Potential of Farm Scale AD in Ireland Tullamore Court Hotel October 22 nd Barry Caslin, Teagasc. Bioenergy Specialist
2 Ireland Situation 2009 Area Farmed Crops Grassland Hill / Rough Land Other Land Crop Potatoes Barley Wheat Oats Oilseed Rape Hay Grass Silage Area (ha) 10, ,105 80,514 18,467 5, ,600 1,211,200 4,261,100 ha 282,086 ha 3,491,767 ha 487,247 ha 45,033 ha Production (tonnes) 380,905 1,260, , ,878 23,200 2,381,400 26,084,100
3 Bioenergy in Ireland Wood residues pulpwood, sawmill residues, forestry residues, recycled wood. Dry agricultural residues Straw, poultry litter, spent mushroom compost. Wet agricultural residues animal manure / slurry Industry residues sludge, fats, meat & bonemeal, food processing residues. Purpose grown energy crops oilseed rape, cereals, maize, sugar beet, short rotation coppice willow, miscanthus. Others recovered vegetable oil
4 White Paper Targets 12% renewable heat by 2020 (5% by 2010). 30% co-firing with biomass at the 3 peat power plants by MW of CHP by % transport biofuels by 2020 (5.75% 2010). The above targets will be the mechanisms to achieve 16% total final energy consumption and a 10% contribution of energy in transport by 2020.
5 Bioenergy Contribution to Total Final Consumption Sector Heat energy Electrical energy Transport energy Total 2010 PJ (ktoe) 14 (336) 2 (48) 12 (288) 28 (672) 2020 PJ (ktoe) 21 (504) 17 (408) 22 (528) 60 (1,440)
6 European Policy Drivers EU Landfill directive 1999 EU Waste Framework Directive (2008/98/EC) The commission will carry out an assessment on biowaste management EU Renewable energy directive 2009
7 National Policy Drivers Regional Waste Management Plans (2001 & 2005/2006) National Strategy on Bio-degradable Waste (2006) Mandatory diversion targets set for 2010, 2013, 2016
8 AD in the EU Germany Austria Denmark Sweden
9 Substrates for AD Animal manure & slurry Agricultural residues & by-products Digestible organic wastes (food & Agri industries) Organic fraction of municipal waste Sewage sludge Dedicated energy crops
10 Advantages of manures & slurries The natural content of anaerobic bacteria. High water content solvent Cheap price High accessability
11 Biogas production The biogas production is determined by: Dry matter content (DM) Organic matter fraction of dry matter (OM/DM) Biogas production per kg of OM
12 Feedstocks MATERIAL TOTAL SOLIDS % VOLATILE SOLIDS RAW % MAT GAS PRODUCED M 3 /Kg V S APPROX CH YIELD/TONNE OF RAW MATERIAL Pig Slurry M 3 Cattle Slurry M 3 Chicken Manure M 3 Food waste M 3 Maize M 3 Grass Silage M 3
13 Waste produced by various livestock Pigs Waste Kg/day Cattle Waste Kg/day Piglet (15kg) 1.04 Calf (0-6) 6 Weaner (30kg) 1.9 Store (6-15) 14 Growing-Finishing (70kg) 4.4 Dairy (6-15) 14 Growing -Finishing 5.8 Beef (25-24) 21 Dry Sow (125kg) 4.03 Dairy (15-24) 21 Sow & Litter 14.9 Beef Cow (24+) 41 Boar (160kg) 4.9 Dairy Cow (24 +) 47 Chickens Chickens Layers 1.8kg 0.1 Broiler (0.9kg) 0.06
14 Dairy Herd 1 m 3 of biogas = 21 MJ of energy 21 MJ of energy = 5.83 kwh (21/3.6) 1 dairy cow produces 0.33 m 3 /slurry/ week Each cow produces 47 kg/slurry/day 1 cow produces (0.047 x 20.00) 0.94m 3 /biogas/day 0.94 m 3 x 5.83 = 5.48 kwh/cow/day Assume electrical efficiency of 35% = 1.9kW el /day
15 Dairy herd continued A farmer having 250 dairy cows with slurry at 10% DM will produce: 250 Cow Dairy herd will produce 12 m 3 of slurry per day. 1 cow produces 1,900 Watts/day 250 cows will produce 173,375 kwh/yr or provide electricity for 41 homes
16 Digesting Maize What's the available area under cultivation? What's the potential electrical power per hectare per year (kw el /ha/year) on average soil and weather conditions?
17 Maize One hectare of maize will yield approximately 13 tonne of DM / ha The DM of fresh maize = Circa 30% Total fresh yield = 43 t/ha Biogas yield = 202 m 3 /tonne 8686m 3 /ha = 182,406 MJ or 50,668 kwh/ha Efficiency 35% = 17,733 kwh/ha One hectare of Maize can provide electricity for over 4 homes per year.
18 Digesting maize continued Assuming every hectare is worth 2.5 kw el electrical power per year, the possible electrical power capacity is calculated by multiplying the area under cultivation with 2.5 kw el /ha. 200 ha x 2.5 kw/ha = 500 kw el
19 Biogas Production Amount of substrate (t) x DM (%) on OM (% of DM) x maximum biogas production (m 3 /t ODM)
20 Biogas production example 1,000 t of pig manure has a DM of 8% of which 80% is organic matter (OM). The max biogas yield is 450 m 3 /t ODM Biogas production will be 1000 t x 8% DM x 80% OM x 450 m 3 /t ODM = 28,800 m 3 biogas.
21 Biogas Composition Component Volume Percentage Methane (CH 4 ) 50-80% Carbon dioxide (CO 2 ) 50-20% Nitrogen (N 2 ) <1% Hydrogen (H 2 ) <1% Ammonia (NH 3 ) <1% Hydrogen Sulphide (H 2 S) <1% At 60% Methane = 21 MJ per m 3 At 100% Methane = 36 MJ /m 3
22 Sizing a digester Digester volume m 3 = [manure ( m 3 /yr) + co-substrate (m 3 /yr) x retention time (days) 365
23 Digester sizing example 5,000m 3 of cattle manure and 1000m 3 of agricultural waste are annually digested with a retention time of 28 days. The digester volume will need to be at least ( ) x (28/365) = 461m 3
24 Post digestion storage Size of post digestion storage (m 3 ) = Animal input substrate (m 3 /yr) x required storage time (months) size of digester 12
25 Example post digestion storage (5, ,000) x (2/12) = 539 m 3
26 Biogas production m 3 /yr = [manure m (t/yr) x DM m x OM m x (m 3 biogas/kg OM m ) x 1000] DM m + [Co-substrate x DM cs x OM cs x M3 biogas/kg OM cs x 1000] DM cs
27 Example 5000 m 3 cattle manure and 1000 m 3 of agricultural waste. Cattle manure density 1t/m 3 has a DM of 10% on OM/MD of 80% and biogas yield of 0.25 m 3 /kg O m. The organic waste with a density of 0.8t (m 3 ) has a DM of 30% and OM/DM of 70% and a biogas yield of 0.55m 3 /kg OM
28 Example calculation Biogas production m 3 /yr = [(5000x1)(t/manure yr) x 10% x 80% x 0.25 x 1,000] + [(1,000 x 0.8)(t waste/yr) x 30% x 70% x 0.55 x 1,000] = 100, ,400 = 192,400 m 3 /yr of biogas
29 Digestate - Potential Benefits Destruction of weed seeds Dependent on retention time, process temperature etc Avoidance of plant burns Burns caused by low density fatty acids most fatty acids broke down in AD process Fertiliser improvement Mineralisation of organically bound nutrients Total P vs Available P
30 Dairy Slurry Digestate % DM %N Ammonium N % %P %K
31 Value of nutrients Nitrogen (N) 0.90 kg Phosphorus (P) 2.50 kg Potassium (K) 1.00 kg
32 Digestate Analysis N P K Kg / tonne of digestate (Av) Value of Digestate Total Value/ ton 9.00
33 Max fertilising rates (grassland) Teagasc green book Grassland < 170 kg/ha = 226 kg/ha N Soil P index 1 = 39 kg/ha P Soil K index 1 = 175 kg/ha K 33 ton / ha Digestate will supply: 66 kg available N 24 kg P 169kg K
34 Amount spreadable on land at 170kg Org N/ha Limit Nutrient requirement N Kg/ha 170 Max Application t/ha 33 ton P ton K ton
35 Anaerobic Digestion Research Developing grass for sustainable renewable energy generation and value-added products led by Dr Padraig O Kiely- Teagasc Grange Energy generation option for pig manure and sustainable disposal of residue led by Dr Peadar Lawlor Moorepark Evaluating Irish grassland as a source for bioenergy: Environmental impacts and long-term sustainability led by UCD with Teagasc Oak Park as collaborators
36 Conclusion The objective of AD is to reduce GHG emissions and produce green energy. Producing green energy through AD will require taxpayers money. AD does not solve a farmers problem of too much manure and too much nutrients. Social & Environmental benefits definitely Economic benefits are marginal!
37 Thank you for your attention! Barry Caslin Teagasc Oakpark Carlow