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More than biogas production

Agri- cul- ture. Envi- ron- ment. Energy. More than biogas production. Biogas. Biogas. Biogas rests on tree legs. Energy. Agriculture. Environment. Short status for Denmark, 2008. A bout 60 farm scale biogas plants

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More than biogas production

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

  2. Biogas Biogas rests on tree legs Energy Agriculture Environment

  3. 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. 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. 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. Mixing and digesting slurry change the characteristic of the slurry

  7. Fertilizer value

  8. Fertilizer value 100 90 80 70 60 Utilization of nitrogen, % of commercial fertilizer 50 40 30 20 10 0 Pig slurry Cattle slurry Digested slurry Winter wheat Spring barley

  9. 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 0 20 40 60 80 100 N-utilization, % (fertilizer equivalent)

  10. Ammonia evaporation in spring barley 50 -N 4 40 30 -loss, % of spread NH 20 10 3 NH 0 2002 2003 Untreated pig slurry Digested pig slurry

  11. Fertilizer plan for nitrogen for 1 ha grass Per hectare Cattle slurry Digested slurry N-requirement, kg 250 250 N in slurry, kg total 170 170 N-utilization, % 40 60 N- in slurry, utilized, kg 68 102 Mineral fertilizer 182 148 Saved, kg Saved, £ - - 34 17

  12. Test results from Ribe Biogas, bacteria per ml. slurry (1998) 6 Log10 germs per ml slurry Date Before After 3 Mar. 18 May 13 July 15 Sept. 9 Nov. 11 1,300,000 140,000 690,000 9,000,000 62,000 <5 <5 <5 <5 <5 5 10 Time, weeks Slurry tank, 6-8°C Mesofile biogas, 35°C Termofil biogas, 53°C Digested slurry is low on germs

  13. Digestion reduces odour

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

  15. Odour concentration in air samples after spreading

  16. Concentration of VFA in slurry

  17. Digestion reduces nitrate leaching Source: Grøn Viden

  18. Digestion reduces emission of green house gases • The total emission of CO2 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

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