More than biogas production Agriculture Biogas Energy Dansk Landbrugsrådgivning Landscentret Environment
Biogas rests on tree legs Biogas Energy Dansk Landbrugsrådgivning Landscentret Agriculture Environment
Short status for Denmark, 2008 • • About 60 farm scale biogas plants 5 percent of all manure in Denmark is digested (about 1. 5 million tonnes) Additionally about 0. 3 million tonnes of organic waste is digested and recycled to farmland 20 large shared biogas plants Dansk Landbrugsrådgivning Landscentret
Agricultural advantages, overview • • • Improved utilization of nutrients Homogeneous and light-fluid slurry Reduced costs for transportation Large amount of declared slurry The slurry is free from disease germs and weed seeds Dansk Landbrugsrådgivning Landscentret
Environmental advantages, overview • • • Reduced leaching of nitrate Lower surplus of phosphorus in the soil Reduced emission of green house gasses Reduced odour problems Controlled recycling of organic waste Dansk Landbrugsrådgivning Landscentret
Mixing and digesting slurry change the characteristic of the slurry DM, P, K, % N-tot, NH 4 N, kg/t Digested slurry 4, 8 4, 4 kg/t 3, 5 1, 0 Pig slurry 5, 0 4, 8 2, 9 Cattle slurry 7, 5 3, 9 2, 4 Dansk Landbrugsrådgivning Landscentret p. H NH 4 N, % 2, 3 7, 6 81 1, 1 2, 3 7, 1 74 0, 9 3, 5 6, 9 61
Fertilizer value Dansk Landbrugsrådgivning Landscentret
Fertilizer value Utilization of nitrogen, % of commercial fertilizer 100 90 80 70 60 50 40 30 20 10 0 Pig slurry Cattle slurry Winter wheat Dansk Landbrugsrådgivning Landscentret Digested slurry Spring barley
Improved fertilizer effect of nitrogen - trials in winter wheat Digested slurry, trailing hoses Pig slurry, trailing hoses Cattle slurry, trailing hoses Digested slurry, injected Pig slurry, injected Cattle slurry, injected Dansk Landbrugsrådgivning Landscentret 0 20 40 60 80 100 N-utilization, % (fertilizer equivalent)
NH 3 -loss, % of spread NH 4 -N Ammonia evaporation in spring barley 50 40 30 20 10 0 2002 Untreated pig slurry Dansk Landbrugsrådgivning Landscentret 2003 Digested pig slurry
Fertilizer plan for nitrogen for 1 ha grass Per hectare N-requirement, kg N in slurry, kg total N-utilization, % N- in slurry, utilized, kg Mineral fertilizer Saved, kg Saved, £ Dansk Landbrugsrådgivning Landscentret Cattle slurry Digested slurry 250 170 40 68 182 - 250 170 60 102 148 34 - 17
Log 10 germs per ml slurry Digested slurry is low on germs Test results from Ribe Biogas, bacteria per ml. slurry (1998) 6 Date 3 5 10 Time, weeks Slurry tank, 6 -8°C Mesofile biogas, 35°C Termofil biogas, 53°C Dansk Landbrugsrådgivning Landscentret Before Mar. 18 May 13 July 15 Sept. 9 Nov. 11 1, 300, 000 140, 000 690, 000 9, 000 62, 000 After <5 <5 <5
Digestion reduces odour Dansk Landbrugsrådgivning Landscentret
Digestion reduces odour Winddirection 5 minutes 12 hours Dansk Landbrugsrådgivning Landscentret Untreated slurry Digested slurry
Odour concentration in air samples after spreading Dansk Landbrugsrådgivning Landscentret
Concentration of VFA in slurry Dansk Landbrugsrådgivning Landscentret
Digestion reduces nitrate leaching Source: Grøn Viden Dansk Landbrugsrådgivning Landscentret
Digestion reduces emission of green house gases • The total emission of CO 2 is about 70 million tonnes • Digestion of all slurry in biogas plants can reduce that • • with about 2. 1 million tonnes That is equivalent to 3 percent! The reduction is a combination of lower emission of methane from manure tanks and a reduction of the use of fossil fuels Sommer, Møller and Petersen, 2001 Dansk Landbrugsrådgivning Landscentret
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