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Coal is the most abundant fossil fuel in the world and is likely to outlast gas and oil for centuries. However, with global issues like climate change at the forefront of public attention there is a trend towards the development of a carbon constrained economy. As a result, research has intensified in the last decade on modes of operating coal fired power plants with carbon capture and storage (CCS). In particular, pre-combustion options via coal gasification, especially integrated gasification combined cycle (IGCC) processes, are attracting the attention of governments, industry and the research community as an attractive alternative to conventional power generation. It is possible to build an IGCC plant with CCS with conventional technologies however; these processes are energy intensive and likely to reduce power plant efficiencies. Novel ceramic membrane technologies, in particular molecular sieving silica (MSS) and pervoskite membranes, offer the opportunity to reduce efficiency losses by separating gases at high temperatures and pressures. MSS membranes can be made preferentially selective for H 2 , enabling both enhanced production, via a water-gas shift membrane reactor, and recovery of H 2 from the syngas stream at high temperatures. They also allow CO 2 to be concentrated at high pressures, reducing the compression loads for transportation and enabling simple integration with CO 2 storage or sequestration operations. Perovskite membranes provide a viable alternative to cryogenic distillation for air separation by delivering the tonnage of oxygen required for coal gasification at a reduced cost. In this review we examine ceramic membrane technologies for high temperature gas separation and discuss the operational, mechanical, design and process considerations necessary for their successful integration into IGCC with CCS systems.

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n 1996, coal was used to generate 25% of the electricity produced worldwide. Because of its large reserves, coal will certainly continue I to play a major role in energy production in North America and worldwide. During the past decade concern has grown about greenhouse gas emissions (CO, , CH, , N, O) and their potential impact on climate change. Since coal-fired power plants account for about 1 1 % of CO, emissions, clean and efficient combustion technologies need to be developed for use in existing and new coal-fired power generation plants.To reduce CO, , one of the most attractive solutions in the medium term is to remove CO, from flue gas stacks. Studies on post-combustion treatment of stack gases from conventional power plants have demonstrated that the energy penalties for CO, separation are high (Smith and Thambimuthu, 1991; Riemer, 1993). Therefore, CO, capture and sequestriation technologies must be developed that offer substantially reduced costs and, when possible, with value-added benefits.One application that offers secondary economic benefits while reducing CO, emissions from coal-fired power generation plants i s the use of CO, in enhanced oil recovery (EOR) operations. The potential for CO, use in EOR is relatively large in the USA and Canada. For example, in Western Canada, it is estimated that about 277 million tonnes of CO, can be stored over a 15-year period through EORoperations. The estimated CO, capacity in this time frame could reduce up to 5% of the annual Canadian CO, emissions. Another very attractive application is the use of CO, for enhanced coal bed methane (CBM) recovery. Methane i s produced from deep coal seams by injecting CO, and with the CO, being retained underground with its preferential adsorption in the coal seams. In the longer term, other environmentally sound, albeit more costly, methods of gas disposal such as in aquifers and disused gas and oil wells can be found for the permanent stroage of CO, removed from coal-fired power generation plants.Conventional technologies for removing CO, from the stack gas in existing coal-fired power plants are expensive because CO, i s diluted (typically about 14 vol% on a dry basis) and because the flue gas needs to be pretreated. The cost of gas separation can be reduced by increasing the concentration of CO, in the flue gas. This can be achieved by increasing the oxygen in the feed gas and, eventually, by recycling part of the flue gas (weller et al., 1985). Coal combustion at higher oxygen concentration is particularly attractive, not only because it helps reduce the cost of CO, separation in the flue gas, but also because it reduces the volume of inert gas present such as nitrogen, thus increasing boiler *Authors to whom correspondence may be addressed. E-mail addresses: ecroiset@ uwaterloo.ca; kelly. thambimuthu@nrcan.gc.ca thesent address: Department of Chemical Engineering, University of Sydney, NSW 2006, Australia.As part of CO, abatement strategies for climate change, we are investigating coal combusion behaviour in various...

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