Greenhouse Gas Analysis of Electricity Generation Systems

All renewable energy systems make some contribution to climate change. This is due to the emission of greenhouse gases from the fossil fuels combusted for their construction, and as back-up energy during their operation. Accurate calculation of greenhouse gas emissions per kilowatt hour of electricity is difficult, but is an important part of policy making and planning. Calculation methodologies and results for different grid-scale electricity generation systems are presented in this paper, with an emphasis on solar thermal systems. Both material inventory and financial-based methods are employed, and the results are compared with other recent studies. For most renewable electricity plants, the emissions have a strong dependence on the capacity factor, back-up fuel, and on the size of the plant. For typical solar thermal plants, the results show that approximately 90 g of CO2 equivalent are released per kWh of electricity generated over the lifetime of the plant.