In combination with downstream methanation sng

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Unformatted text preview: ed oxygen- blown gasification with downstream methanation routes are the most promising options for SNG production from relatively dry biomass. In combination with downstream methanation, SNG production efficiencies up to approximately 70% (on LHV basis) can be achieved. The specific investment costs of a system with a thermal biomass input of 100 MW are higher for pressurised oxygen- blown gasification compared to indirect steam- blown gasification, mainly due to the requirement of an oxygen plant. The SNG production costs for a 100 MWth system and biomass costs of 2.3 €/GJwood range from 7.8 to 8.5 €/GJSNG, while based on the Dutch stimulating measures, valid in 2002, the actual market price for “Green Gas” was calculated to be 8.7 €/GJSNG. The CO2 emission reduction costs range from 83 to 95 €/tonne, which is lower than the 100 €/tonne tax exemption for green power. Table 1 Model-based composition and quality of SNG versus Dutch natural gas (Slochteren quality). Property Composition CH4 (incl. C2+) H2 CO2 N2 NG vol.% vol.% vol.% vol.% Calorific value, LHV MJ/kg MJ/Nm3 Wobbe-index MJ/Nm3 O2-blown gasifier indirect gasifier hydrogasifier 84.75 0.00 0.89 14.35 87.67 1.77 8.65 1.84 87.62 1.95 8.90 1.44 82.97 8.02 8.37 0.53 38.0 31.7 38.41 31.26 38.41 31.26 39.57 30.67 43.46-44.41 43.74 43.74 44.03 Table 2 Evaluation data for gasification-based SNG production processes. O2-blown indirect hydrogasification gasification gasification Thermal input biomass hydrogen Efficiency SNG production Carbon conversion Specific investment costs SNG production costs Dutch market price “Green Gas” Costs CO2 avoided MW MW % % €/kWth €/GJSNG €/GJSNG €/tonne 100 100 66.3* 93.3 482 8.5 8.7 95 67.0* 100 449 7.8 8.7 83 50 47 79.1 80.1 616 5.6 5.2 115 * When the separated tar from the product gas is recycled and converted within the gasifier, SNG production efficiencies up to 70% (on LHV basis) can be achieved. ECN-RX--04-085 11 The up-scaling potential of the indirect gasification technology is ex...
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