Dansk Landbrugsrådgivning Landscentret More than biogas production Biogas Envi- ron- ment Agri- cul- ture Energy

Dansk Landbrugsrådgivning Landscentret Biogas rests on tree legs Biogas EnergyEnvironmentAgriculture

Dansk Landbrugsrådgivning Landscentret 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, % N-tot, kg/t NH 4 - N, kg/t P, kg/t K, kg/t pHNH 4 - N, % Digested slurry Pig slurry Cattle slurry 4,8 5,0 7,5 4,4 4,8 3,9 3,5 2,9 2,4 1,0 1,1 0,9 2,3 3,5 7,6 7,1 6,

Dansk Landbrugsrådgivning Landscentret Fertilizer value

Dansk Landbrugsrådgivning Landscentret Fertilizer value Pig slurryCattle slurryDigested slurry Utilization of nitrogen, % of commercial fertilizer Winter wheatSpring barley

Dansk Landbrugsrådgivning Landscentret Improved fertilizer effect of nitrogen - trials in winter wheat Cattle slurry, injected Pig slurry, injected Digested slurry, injected Cattle slurry, trailing hoses Pig slurry, trailing hoses Digested slurry, trailing hoses N-utilization, % (fertilizer equivalent)

Dansk Landbrugsrådgivning Landscentret Ammonia evaporation in spring barley NH 3 -loss, % of spread NH 4 -N Untreated pig slurryDigested pig slurry

Dansk Landbrugsrådgivning Landscentret Fertilizer plan for nitrogen for 1 ha grass 250 N-requirement, kg 170 N in slurry, kg total 6040N-utilization, % 10268N- in slurry, utilized, kg Saved, kg Saved, £ Mineral fertilizer Digested slurry Cattle slurryPer hectare

Dansk Landbrugsrådgivning Landscentret Digested slurry is low on germs <5 1,300, , ,000 9,000,000 62,000 Mar. 18 May 13 July 15 Sept. 9 Nov. 11 AfterBeforeDate Test results from Ribe Biogas, bacteria per ml. slurry (1998) Log 10 germs per ml slurry Time, weeks Slurry tank, 6-8°C Mesofile biogas, 35°C Termofil biogas, 53°C

Dansk Landbrugsrådgivning Landscentret Digestion reduces odour

Dansk Landbrugsrådgivning Landscentret Digestion reduces odour Wind- direction Untreated slurry Digested slurry 5 minutes 12 hours

Dansk Landbrugsrådgivning Landscentret 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