The environmental effects of anaerobic digestion (AD) plants have not, to date, been thoroughly analysed.
The technology of biogas production has developed enormously in the last 10 years, with equipment
functioning at ever-improving efficiency. In the present study, we aimed to examine the environmental
effects of biogas plants that operate with the same power production capacity, but use different raw
materials during the full life cycle. In addition, the environmental effects that occur during the establishment
of AD plants were defined and contrasted against emissions during the full life cycle. In life
cycle analysis (LCA), the greenhouse gas (GHG) emission effect of biogas production was measured as kg
CO
2
eq/kWh
e
, the acidification potential as kg SO
2
eq/kWh
, and the eutrophication potential as kg
PO
4
eq/kWh
e
e
. The calculations proved that an AD plant that processes only energy crops as raw materials
can be regarded as a CO
2
absorber (188 g/kWh
e
). The CO
emission of all three examined plants was
below the average emission of electrical power currently produced in a conventional manner. The AD
plant that processes low-energy-density agricultural wastes produced 7.7% of its full-life-cycle CO
2
emissions during its construction phase, compared with a 0.9% ratio for the AD plant processing only
energy crops. However, the manure-based AD plant contributed the most to the decline in environmental
acidification.
2