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Title:
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Vergassing van natte biomassa / reststromen in superkritiek water (SWG), voor de productie van groen gas(SNG), SNG/H2 mengsels, basis chemicaliën en puur H2
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Author(s):
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Published by:
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Publication date:
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ECN
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1-12-2004
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ECN report number:
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Document type:
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ECN-C--04-107
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ECN publication
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Number of pages:
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Full text:
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35
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Download PDF
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Abstract:
The Dutch government has set the policy
target that in 2020 10% of the total energy consumption has to be provided
by means of renewable energy sources. Biomass is expected to play a
major role in this future renewable energy based supply system.
This study is a feasibility study that has
been carried out, in order to evaluate the potential of supercritical
water gasification (SCWG) of relatively wet biomass / waste streams
(70-95 gew % water) for the production of ?Green Gas? (SNG: Synthetic
Natural Gas), SNG/H2 mixtures, chemicals, or hydrogen. At
temperatures and pressures above the critical point of water (Tc
= 373.95oC, Pc = 220.64 bar) there is no distinction
between gas phase and liquid phase. Also the behaviour of water will
change considerably at these supercritical conditions, and water will
even be consumed as a reactant. At relatively low temperatures, just
below the critical temperature, catalysts are required and gases rich
in methane can be produced. At higher temperatures and supercritical
conditions, hydrogen rich gases are formed, especially from low concentration
feedstock. When the biomass concentration in water increases, the product
will gradually contain more hydrocarbons and full conversion becomes
difficult. Other aspects that also need to be solved are: the feeding
system, pollution / corrosion of the heat exchanger, gas cleanup and
the cleaning of a large volume of wastewater. According to a first rough estimation, the production costs of
the product gas, SNG/H2 mixtures, by the SCWG process are relatively
high, even when the feedstock would be available for free. This is due
to relatively high investment costs of this process, compared to other
biomass/waste-related SNG production technologies. An important potential
to reduce the production costs in the SCWG process is the application
of wet organic waste streams as feedstock, with a negative market value.
Therefore, organic waste treatment is a promising application for the
SCWG process.
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