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Unformatted text preview: njection into the natural gas grid, and
transport as “Green Gas” to customers, would be more advantageous.
In order to obtain pipeline quality gas, the biogas must pass through two major
(1) A cleaning process, in which trace components (hydrogen sulphide, water,
particles, halogenated hydrocarbons, ammonia, oxygen, and organic silicon
compounds) harmful to the natural gas grid, appliances, or end-users, are
(2) An upgrading process (basically separation of methane and carbon dioxide), in
which the calorific value, Wobbe-index and other parameters are adjusted in order
to meet the pipeline specifications (furthermore, the gas must be odourised before
it is added to the natural gas grid).
In 2001, 27 landfill projects in the Netherlands delivered 2*107 Nm 3 natural gas
equivalent to the gas distribution net, while the contribution of biogas from digestion
projects was about 3*107 Nm 3 natural gas equivalent. Compared to annual Dutch gas
consumption of 4*1010 Nm3, the contribution of landfill gas and digestion gas was,
therefore, 0.1%. Taking into account the additional potential for digestion gas, a total
contribution of about 0.5% of the annual Dutch gas consumption can be achieved.
Although very limited, the short-term exploitation of this potential, as “Green Gas”
would be interesting.
If biogas is distributed in a closed biogas network or in a town gas network, only
cleaning of biogas is necessary. This option has been demonstrated in Sweden and
Denmark. Utilisation of the natural gas grid, as a transporting system for biogas,
plays an important role in promoting the use of biogas as a vehicle fuel, as it will be
possible to produce biogas in any place along the gas grid, with the possibility to trade
100% of the gas as vehicle fuel. In Switzerland gas as a fuel for vehicles is becoming
more and more popular. Both natural gas and biogas are utilised as vehicle fuel. Also in ECN-RX--04-085 5 Sweden biogas has become very popular as a fuel for vehicles (end 2000 about 4000
vehicles operated on biogas). During the last years many upgrading...
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- Spring '08
- Chemical Engineering