Life cycle assessment of energy generation of biogas fed combined heat and power plants: Environmental impact of different agricultural substrates

Publication Type

Journal contribution (peer reviewed)

Authors

Lansche, J; Müller J

Year of publication

2012

Published in

Eng. Life Sci.

Pubisher

Wiley-VCH

Band/Volume

12/3

DOI

10.1002/elsc.201100061

Page (from - to)

313-320

Keywords

greenhouse gas emission

The utilization of agricultural biomass for anaerobic digestion is increasing in Germany
since the first version of the Renewable Energies Sources Act (EEG) in 2000.
Main products of this conversion process are biogas and digestate, whereby the
biogas is mainly used for generation of heat and electricity in combined heat and
power plants (CHP). This study investigated the potential environmental impact of
anaerobic digestion processes with different agricultural substrates by the life cycle
assessment (LCA) method. It focuses on liquid manure and energy crops as feedstock
on the one hand and a comparison of four virtual model plants on the other hand.
Besides global warming potential (GWP), the impact categories eutrophication potential
(EP) and acidification potential (AP) are presented in this work. The results
show that greenhouse gas emissions can be reduced with anaerobic digestion of
liquid manure as well as energy crops, particularly when digestate storage tanks are
gas-tight.When energy crops are fermented together with liquid manure, the biggest
credit for the avoidance of greenhouse gas emissions was given for the generation
of electricity. The results differ from those of GWP when looking at the AP and the
EP. These impact categories show similar results with a reduction of emissions for
liquid manure in mono-digestion but increasing emissions for digestion of energy
crops together with 0–35% liquid manure.