Agriculture Reference
In-Depth Information
transportation system is operated and paid for by the biogas plant. The
digested manure is, by the farmer's decision, returned either to the farm or
to a so-called decentralised storage tank somewhere else. Hereby the
farmer
benefits
from
cost savings in manure transportation
(Hjort-
Gregersen 1993).
In a centralised biogas plant pig slurry is mixed with cattle slurry
and various types of organic waste. Danish experience show that the slurry
mix, as a fertiliser, is more advantageous than conventional slurry. This is
due to the additional nutrients from often relatively concentrated organic
waste. But also composition of the slurry mix makes a difference. Pig
slurry often contains a phosphorus surplus but a potassium deficit for a
typical crop rotation on pig farms. Cattle slurry, on the contrary, often
contains a potassium surplus but a phosphorus deficit for typical crop
rotations on cattle farms. Consequently, the digested slurry mix is more
valuable for both pig and cattle farms than their respective conventional
slurry. A higher nutrient utilisation is achieved, and farmers gain benefits
from
cost savings in fertiliser purchase
(Hjort-Gregersen 1993).
Naturally the size of the derived economic benefits are dependent
on the actual situation on each farm. Calculations in Hjort-Gregersen
(1993) show that farmers may gain an average of 5 DKK. per slurry
supplied to the biogas plant. The benefits mainly derive from cost savings
in slurry storage and fertiliser purchase. In addition, less odour nuisances
appear from digested compared to conventional slurry. This is very much
appreciated by farmers, who otherwise
often become increasingly
unpopular in times of slurry spreading.
8. PERSPECTIVES ON A NATIONAL AND EUROPEAN
LEVEL
In Denmark, as well as in many other European countries, considerable
potential for biogas production exists. In 1998 a total of 1.1 million tonnes
of manure and 0.2 million tonnes of organic waste were applied to
centralised biogas plants in Denmark. These biomass amounts account for
approximately 2.5 per cent of total manure, and approximately 8 per cent
of organic waste available in Denmark. It appears that manure and organic
waste represents a tremendous potential for biogas production in Denmark.
Similar potentials can be found in other European countries, which appears
from Table 12.4. It appears that many EU countries have considerable
potentials for biogas production. Particularly those with widespread
livestock production, as animal manure accounts for the vast majority of
biogas production potential in Europe. Based on 1993 data, realisation of
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