Comparison of options for reducing greenhouse gas emissions must take account of many different matters in a consistent manner. A method of full-fuel-cycle analysis has been developed with this aim in mind. In this method, technical options are compared using a measure made up from the ”private costs” of owning and operating a power station together with the ”external costs” representing its environmental impact. The method is tested on three types of power generation plant, each of which incorporates CO2 capture and sequestration technology – these include natural gas-fired and coal-fired power plant, as well as CO2 storage in a disused gas field, in the deep ocean or in an off-set forest. Emissions arising from all stages of the fuel cycle are estimated – from extraction of fossil fuel through to dispatch of power to the grid. All types of emission and their impact at local, regional and global level are assessed and valuation of these impacts is attempted. Previous work in this field has concentrated on local impacts, such as occupational health, and regional impacts, such as ”acid rain”. This study is one of the first to include a comprehensive assessment of global warming impacts, how these will vary with time as well as geographically, including allowance for any potential benefits. From this, the environmental external costs of the fuel cycles are determined.