BIOENERGY FOR EUROPE: WHICH ONES FIT BEST?

7.1 Country specific life cycle comparisons 103
Biogas from swine excrement versus natural gas for combined heat and electricity production
– Austria
Use of fossil fuels
Greenhouse effect
Acidification
Eutrophication
Summer smog
Nitrous oxide
Human toxicity
How to interpret the diagram
Advantages for
biofuel
-4000 -3000 -2000 -1000 0 1000 2000
Austrian inhabitant equivalents per 100 TJ
Advantages for
fossil fuel
The figure shows the results of comparisons between complete life cycles where natural gas for small
scale combined heat and electricity production is substituted by biogas. The unit refers to an amount of
100 TJ net energy output, the ratio of heat to electricity is 1 to 1.11. In this case for example the amount
of fossil fuel saved is equal to the amount which about 1,100 Austrian citizens would on average consume
in one year (this is what is meant by "Austrian inhabitant equivalents").
Conclusions
In 1999 the total Austrian livestock amounted to 2.14 million LSU (livestock unit). The share in pigs
amounted to 412,510 LSU, including 111,176 LSU in 3118 undertakings of more than 50 LSU. The
production of biogas out of excrement seems to be of interest especially with undertakings of such size.
With the biogas production out of the liquid manure of 100,000 pig-LSU 0.3 PJ fossil fuel and 0.05 Mt
CO2 can be saved. The effect on acidification, eutrophication, summer smog and nitrous oxide will be
low (+ 0.15 kt SO2, + 0.09 kt NO3, - 0.03 kt ethylene eq. and + 0.0002 kt N2O).
Biogas shows advantages concerning the use of fossil energy and clear advantages concerning the emission
of greenhouse gases. 0.02 % of the Austrian demand in primary energy can be covered by the liquid
manure of 5 % of the entire livestock. Biogas can contribute almost 0.6 % to the demanded reduction
in greenhouse gas emissions of 9.4 million tons. The effects on the impact categories acidification,
eutrophication, summer smog, nitrous oxide-emission and human toxicity are minimal.