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Co-production of fuels as an option for Demkolec? : a preliminary review of opportunities for the co-production of liquid or gaseous energy carriers
Gepubliceerd door: Publicatie datum:
ECN BM 1-3-2001
ECN publicatienummer: Publicatie type:
ECN-C--01-004 ECN rapport
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This study comprises a preliminary review of the opportunities for the co-production of liquid or gaseous energy carriers at the 253 MWe coal gasification combined cycle (IGCC) power plant of Demkolec in Buggenum, the Netherlands. Demkolec is actively pursuing various options to optimise the economics of the plant to become a strong competitor on the liberalised power market. In this respect, it has initiated already a substitution of approx. 50% of the coal consumption of this plant by cheaper alternative fuels. Part of this alternative fuel input will provide an extra product income, because this part comprises organic material that is regarded "green". In addition, Demkolec has recognised that fuels co-production may be an opportunity to further improve the economics of the plant.In the present situation, the plant is operated at partial load (approx. 57%) during off-peak hours since off-peak electricity production is not cost-effective. However, by maintaining the gasification unit at full load during off-peak hours, a surplus of syngas could be produced, which could be converted into liquid or gaseous energy carriers. In this study, four options for off-peak co-production have been examined from a technical and economic point of view, viz. co-production of hydrogen, methanol, Fischer-Tropsch transportation fuels and Substitute Natural Gas (SNG). For the co-production of methanol, a further distinction has been made between the Lurgi process including prior adjustment of the H2/CO ratio (CO-shift) and Air Products? Liquid Phase Methanol (LPMEOH TM ) process without this prior adjustment, and between the production of Fuel Grade and AA Grade methanol. For each co-production option, either a specific process configuration has been considered for which specifications of the process streams and costs were available from other studies or only a general configuration with rough estimates for the process stream specifications and costs. This means that for all options other process configurations are possible and that the selected ones have not been optimised for the Demkolec plant. It has been assumed that the gasifier is operated on the new fuel mixture. Hydrogen and Lurgi methanol are identified as technically the most mature options, whilst LPMEOH methanol is the most flexible one. All co-production options, except for Fischer-Tropsch transporations fuels, are found to be financially viable, but the viability appears to be strongly dependent on the product market price. The co-production of Lurgi (AA Grade) Methanol proves to yield the highest net yearly income for the given best estimates of the product market price. The economics of hydrogen and SNG co-production are quite comparable. The co-production of Fischer-Tropsch transportation fuels is not financially viable at the assumed fossil crude oil price of 15 US$/barrel; a price level of at least 23-29 US$/barrel is required. Apart from the viability of the co-production options, two alternative modes of plant operation have been considered. Firstly, it appears that electricity production during off-peak hours can be made cost-effective if the plant switches to the new fuel mixture, through a combination of lower fuel cost and a green premium on the biomass component of the feed. Consequently, full-load power generation may become an attractive alternative. The calculated additional net yearly income is fairly large compared to the values for the different co-production options and no additional investments or risks are involved. However, given the present situation on the liberalised electricity market, continuous full-load power generation is probably not the most profitable alternative. A second alternative is to operate the Demkolec plant in a regulating power mode. This mode of operation enforces the opportunities for fuels co-production. With a sufficient flexibility of the co-production process, load changes in the electricity production can be matched by changing the load on the co-production section. It is recommended to evaluate the alternative of regulating power mode operation in combination with fuels co-production more thoroughly, as it represents the most likely future for the Demkolec plant and it offers important opportunities to further increase its overall financial-economic performance.

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