ECN publication
Vergassing van natte biomassa / reststromen in superkritiek water (SWG), voor de productie van “groen gas”(SNG), SNG/H2 mengsels, basis chemicaliën en puur H2
Hemmes, K.; Beld, L. van de; Kersten, S.R.A.
Published by: Publication date:
ECN 1-12-2004
ECN report number: Document type:
ECN-C--04-107 ECN publication
Number of pages: Full text:
35 Download PDF  


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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