Page 28 - European Energy Innovation - Autumn 2016 publication
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28  Autumn 2016 European Energy Innovation


Mechanisms of the contribution
of anaerobic digestion (AD) to
GHG-emission abatement:
more than only the substitution
of fossil energy

By Meers, E. *a, Scheidl, S.*, Kirchmeyr, F.*b, Pflüger, S*. Stambasky, J.*c

A naerobic digestion                       energy for these energy applications.    emissions which make anaerobic
               (AD) makes a major                                                   digestion unique as a renewable
               contribution to reduction   IN ADDITION, THERE IS SIGNIFICANT        energy technology. AD therefore brings
               of greenhouse gas (GHG)     POTENTIAL FOR FURTHER BIOGAS             by far the best reduction in CO2 eq per
emissions. The generated products –        PRODUCTION FROM VARIOUS                  unit of energy produced.
biogas, biomethane and biofertilizer       FEEDSTOCKS
– substitute fossil energy, circulate      Taken AD and gasification together,      Avoided methane emission from
nutrients and provide adequate             a conservative estimate for the total    manure storage
waste management as well as more           production of biomethane equivalent      The EU is largely dependent on animal
sustainable agriculture.                   in 2030 is 48 billion Nm3 per year, in   husbandry for feeding the continent
                                           other words a combined renewable         which also produces 1.27 billion
CURRENTLY AD AND GASIFICATION              energy production of 1700 PJ and 62.5    tonnes of manure each year. Methane
PRODUCE THE FOLLOWING IN THE               million tonnes of CO2eq savings for the  emissions from manure storage
EU-28                                      entire EU-28.                            contribute significantly to the overall
Energy for heat, power and transport:                                               GHG emissions, making agriculture one
Currently, around 9.6 billion Nm3          Based on feedstock potential and with    of the major contributors. Nonetheless,
biomethane equivalent are produced         the right policies in place, by 2030,    when manure is brought to a digester
each year (EBA), constituting a calorific  the industry could produce renewable     rather than having it stored for up to nine
value of 420 PJ of energy in the form      energy equivalent to approximately       months, the methane which is naturally
of renewable electricity, heat and         10% of the EU’s current natural gas      produced by anaerobic microorganisms
‘advanced biofuels’ (i.e. fuels made       consumption, for use in electricity      in the manure is captured and put to
from waste). This corresponds to 900       generation, heating/cooling and as a     good use for renewable energy. Since
kg of CO2eq per MWh when producing         transport fuel.                          methane is equivalent to 21 CO2eq
electricity from bituminous coal (US                                                digesting manure has a huge potential in
Energy Information Administration),        ADDITIONAL PATHWAYS OF GHG               lowering the carbon footprint of modern
56.1 kg CO2eq per GJ when using            EMISSION ABATEMENT                       agriculture. Dependent on the animal
natural gas for heating (IPCC Default),    In addition to the current output in     and type of manure, approximately
73.2 kg of CO2eq per GJ when using         renewable energy and the apparent        20-60 Nm3 of biogas is produced per
diesel as car fuel). Approximately 12.5    and obvious link to the GHG emission     tonne, which on average is equivalent to
million tonnes of CO2eq are avoided        abatement by replacing fossil fuels,     approximately 180 kWh of energy or 150
each year in Europe by replacing fossil    there are surplus reductions in GHG      kg CO2eq from energy substitution AND

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