Environmental aspects of using animal manure as an energy source

1. Environmental aspects of using animal manure as an energy source Jørgen E. Olesen

2. Manure as an energy source Manure contains organic matter (VS – volatile solids), which may be used as an energy source. Anaerobic digestion (biogas) can provide electricity and heat, and at the same time reduce other emissions from manure. Burning (incineration) of the solid parts of the manure may also produce energy and reduce some emissions

3. Manure sources in Denmark (million tons per year) The energy potential i biogas in the slurry has been estimated as 14.2 PJ, and the potential for biogas from all manure is about 25 PJ.

4. Flows affecting GHG emission from manure handling

5. Factors affecting emissions of N2O and CH4

6. Mitigation of GHG emissions - animal manures

7. Biogas • Energy production (electricity and heat - substitution of fossile energy sources – depends on addition of other organic energy sources) • Reduced methane emissions (requires collection of methane after the biogas reactor) • Reduced nitrous oxide from the manure after field application • Easier handling and improved N use efficiency in the field • Possible to combine with treatment of other organic wastes

8. Current trends in biogas in Denmark½ • The building of new biogas plants in Denmark has virtually stopped. • The reason for this is a number of current barriers for the futher implementation: • The subsidy on the electricity production from biogas has been reduced • It is often difficult to get the location of a new biogas plant approved due to resistance from the local community • Increasing difficulties in obtaining low-cost energy rich wastes for improving biogas production

9. Manure flows with and without biogas

10. Scenarios for biogas production

11. Scenarios for biogas production Reference Reference Reference Biogas I Biogas I Biogas I Biogas II Biogas II Biogas II Pigs Cattle Organic waste

12. Centralised biogas plants in Denmark

13. Energy production from biogas plants in Denmark

14. Current trends in biogas in Denmark • The building of new biogas plants in Denmark has virtually stopped. • The reason for this is a number of current barriers for the futher implementation: • The subsidy on the electricity production from biogas has been reduced • It is often difficult to get the location of a new biogas plant approved due to resistance from the local community • Increasing difficulties in obtaining low-cost energy rich wastes for improving biogas production

15. Incineration of solid fraction of separated slurry Reduction in GHG emissions (kg CO2-eq. per ton slurry) from incineration of separated solid fraction.

16. Conclusions • Both biogas from manure and burning of solid manures can produce energy with a potential of >25 PJ in Denmark. • Both biogas and burning of solid manures will reduce other greenhouse gas emission (methane and nitrous oxide) • Biogas will also lead to increases in utilisation of the nitrogen in the field applied manure. • There are a number of barriers for implementation that needs to be dealt with and there is currently a need to subsidise the technology

17. More information at www.manure.dk