Environmental Engineering Reference
In-Depth Information
equipment availability. Results of cost calculations show that for high feed-
in volumes (700m
3
/h biomethane), high equipment availability is a must
and therefore all major units (e.g. the compressor) should be redundant.
Equipment availability cannot only be improved by redundant equipment
but also by preventive maintenance and repair and shorter maintenance
intervals.
Under a macroeconomic perspective, investment in the network connec-
tion is less important than the running costs and therefore particular
attention should be given to the choice of the grid connection point and the
method of gas conditioning.
Lopsided optimization of feed-in facilities should be avoided. Savings in
investment costs by the gas supplier should not be made at the expense of
the gas network operator. There is no single solution available because in
practice many fringe conditions must be considered.
There is a chance that more cost-effective monitoring equipment may
become available in the near future, but associated potential cost reductions
cannot be calculated at this point in time. The possibility of cost reductions
from the manufacture of standardized components in large numbers is far
better and therefore good engineering practice and simple, appropriate
technical standards should be the priority targets.
The gas treatment technologies available in the market are mature and as
such do not allow for major cost reductions. Improved maintenance and
repair strategies and further optimization of energy efficiency might be
overcompensated by stricter safety and emission control standards. It is thus
more likely that the combined cost of biomethane production and feed-in
will remain at the present level. Recompression still has technical
optimization potential because the operating expenditure for recompression
accounts for about 60% of total operating costs. Furthermore, the methane
loss should be reduced to a minimum (lost profit) and product gas lost from
compression be returned to the process.
16.7 Conclusion and future trends
In the first decade of the 21st century in Europe there has been a growing
trend towards upgrading of biogas to pipeline-quality biomethane for feed-
in into natural gas networks. Different countries have approached grid
injection of biomethane in different ways until quite recently. Adoption of
the European renewables directive in 2009 (European Commission, 2009)
formalized the approach to grid injection of biomethane, at least in Europe.
The technical requirements for grid injection set by the European renew-
ables directive have provided an impetus to provide more uniform rules for
implementation. At the same time, the rapid expansion of biomethane
production has demanded the establishment of comprehensive rules for grid
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