Environmental Engineering Reference
In-Depth Information
without involvement or checking of the operator, but back-tracing is
possible. After application, the specific amount is depleted and cannot be
used further.
The schemes differ in some respects. In Vertogas, auditing of production
facilities and biomethane amounts takes place on a monthly basis; the
German biogas register does not specify any interval. Biogasregister
Deutschland's amounts are entered manually into the accounts, whereas
Vertogas transfers feed in meter readings automatically to the database. The
smallest unit in Vertogas is 1MWh (about 100Nm
3
of gas equivalent);
Germany's Biogas register's smallest unit is 1 kWh.
19.5
Future trends
Biomethane will be an important piece of the puzzle during the conversion
of our energy system to renewable sources. Production of power on demand
from biomethane directly connects the gas grid and the power grid - the gas
grid can help to balance the power grid. The gas grid may change its face
from distribution of fossil gases to being the energy balancing service
provider with short-term and seasonal storage options.
Increasing integration of decentralized biomethane feed-in into the gas
grid is a new situation for the gas grid infrastructure with new challenges.
New gas sources and therefore new paths of transportation may make grid
adaptations at all pressure levels necessary, starting with the distribution
grid. There are examples in Germany of facilities feeding in more
biomethane to the local distribution network than is discharged in total;
the excess gas is compressed and transferred to a higher level.
With increasing biomethane production from energy crops, its impact on
agriculture will come into sharper focus. The obligation of applying
sustainability criteria to biomethane production may be expected in the near
future. The case of biomethane can make some favorable contribution to the
discussion: by application of digestion residues as fertilizers near the
production site, local nutrient cycles can be closed. Additionally, energy-
intensive production of nitrogen fertilizers and exploitation of declining
global phosphorous reserves can be avoided. Further utilization of biomass
waste potential may also close loops in the recycling economy and is
probably a trend in the coming years.
Biomethane is the most efficient biofuel with regard to fuel production
equivalent per area of crop land. Biomethane is expected to play a bigger
role in the fuel market due to government support, increasing application in
NGVs and with regard to GHG emissions (FNR, 2009).
Slowly increasing awareness of biomethane is evident in the legislation of
European countries. The perception is shifting from being regarded as a sub-
branch of biomass production to being an independent renewable energy
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