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

2. Dansk Landbrugsrådgivning Landscentret Biogas rests on tree legs Biogas EnergyEnvironmentAgriculture

3. 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

4. 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

5. 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

6. 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 6,9 81 74 61

7. Dansk Landbrugsrådgivning Landscentret Fertilizer value

8. Dansk Landbrugsrådgivning Landscentret Fertilizer value 0 10 20 30 40 50 60 70 80 90 100 Pig slurryCattle slurryDigested slurry Utilization of nitrogen, % of commercial fertilizer Winter wheatSpring barley

9. Dansk Landbrugsrådgivning Landscentret Improved fertilizer effect of nitrogen - trials in winter wheat 020406080100 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)

10. Dansk Landbrugsrådgivning Landscentret Ammonia evaporation in spring barley 0 10 20 30 40 50 20022003 NH 3 -loss, % of spread NH 4 -N Untreated pig slurryDigested pig slurry

11. 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 34 17 ---- Saved, kg Saved, £ 148182Mineral fertilizer Digested slurry Cattle slurryPer hectare

12. Dansk Landbrugsrådgivning Landscentret Digested slurry is low on germs <5 1,300,000 140,000 690,000 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 10 6 5 3

13. Dansk Landbrugsrådgivning Landscentret Digestion reduces odour

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

15. Dansk Landbrugsrådgivning Landscentret Odour concentration in air samples after spreading

16. Dansk Landbrugsrådgivning Landscentret Concentration of VFA in slurry

17. Dansk Landbrugsrådgivning Landscentret Digestion reduces nitrate leaching Source: Grøn Viden

18. 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