Environmental Engineering Reference
In-Depth Information
structure. On a transport grid level, the application of a computer-based
heating value reconstruction method is the most widely practised alternative
to conditioning; in some cases, feed-in as additional gas is also possible. In a
regional network and, particularly, in the end distribution network, the
definition of heating value zones should be envisaged. In the long term,
computer-based heating value reconstruction methods could become
equally cost effective.
16.5 Economic aspects of biomethane injection
The total costs of network connection (investment and operating costs) vary
greatly. The most important factors are volume flow, network pressure and
distance to the gas network (also see Table 16.2). The investment costs are
further governed by the quality of design (redundancy) and the operating
costs due to the nature of the energy value adjustment (LPG admixture or
alternative method).
The highest investment costs are due to the compressor assembly
(approximately 60% of the investment), followed by the measuring
equipment (metering and gas quality measurement) and pipeline construc-
tion costs (connecting pipeline). The operating costs, on the other hand, are
dominated by the costs of the conditioning gas and electricity consumption
for recompression to network pressure. Absolute investment costs hardly
increase with the size of the facility, which explains why small installations
entail relatively high specific costs (Fig. 16.4). A project requiring a long
pipeline should be equipped with a redundant compressor unit. In that case,
the investment costs will double.
As an example, the specific investment costs for connection to a medium-
pressure network (maximum network operating pressure of 16 bar) drop
from 12,240
/m
3
gas throughput per hour (for a facility with 125m
3
/h
biomethane) to 2457
€
/m
3
hourly gas throughput (700m
3
/h biomethane).
The picture is similar for the operating costs (full cost calculation), which
are dominated by the capital costs even for facilities with medium gas
throughputs (up to 350m
3
/h biomethane). Injection into a distribution grid
with a pressure
€
1 bar involves low investment and operating costs. When
biogas is fed into high-pressure pipelines (e.g. 55 bar), compression costs will
go up by up to 50% when the network pressure is raised from 16 bar, but
will still account for only one third of the annual operating costs. Table 16.8
shows examples of costs for gas network connections.
<
16.6 Optimization and efficiency increase
Many mature upgrading technologies for the separation of CO
2
are
commercially available (see Chapter 15 of this topic). Leading suppliers of
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