Environmental Engineering Reference
In-Depth Information
natural gas grids; what can be seen as an exceptional case for the utilization
of landfill gas in Europe. In the following years, especially in Sweden and
Switzerland, many new upgrading projects were initiated. For more than
10 years, Sweden and Switzerland were the leading countries in biogas
upgrading to biomethane.
Currently, the most ambitious activities can be found in Germany. The
German government defined targets for the production and sustainable
utilization of biomethane and, as a consequence, 83 biogas upgrading plants
were in operation by the end of 2011. Figure 15.1 shows the number of
biogas upgrading plants and raw biogas upgrading capacities in Europe at
the end of 2011.
Figure 15.2 gives an overview of the development of the upgrading
capacity of identified European biogas upgrading plants since 1987. At the
end of 2011, there were 200 plants in operation. These plants have an
upgrading capacity of
162,000m n 3 /h raw biogas to biomethane. This
upgrading capacity corresponds to an energetic capacity of 1.1GW (upper
heating value, Hs) related to biomethane (assuming average 60% methane
content in the raw biogas and 1% methane loss in the upgrading process).
~
15.3 Biogas cleaning and upgrading technologies
To be able to inject biogas into natural gas grids or for direct utilization as
vehicle fuel, it is necessary to clean and upgrade the raw biogas. Cleaning
means the separation of undesired gas compounds and upgrading refers to
the separation of CO 2 .
15.3.1 Biogas cleaning combined with biogas upgrading
The necessity and applicable technologies or strategies for biogas cleaning as
a preliminary step to upgrading differ compared to the case when the biogas
is to be used directly as raw gas (e.g. in combined heat and power (CHP) or
directly for heat production). The main parameters that define the necessary
biogas cleaning steps are
￿ ￿ ￿ ￿ ￿ ￿
.
composition and origin of the raw biogas (e.g. biowaste, sewage sludge,
energy crops, manure, etc.)
.
subsequent upgrading technology according to the specification of the
upgrading plant provider [8].
Humidity removal and drying
Biogas leaving the digester is saturated with water vapour. This water has to
be separated from the gas flow to avoid disruptions in operation of the
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