Nuclear Technology / Volume 160 / Number 2 / November 2007 / Pages 233-243
Technical Paper / Thermal Hydraulics
By using a combination of a nuclear reactor that emits no carbon dioxide and a high-efficiency gas turbine cycle, electric utilities can reduce their generating cost as well as minimize greenhouse gas emissions. The economic competitiveness of pure natural-gas combined-cycle (NGCC), nuclear-assisted NGCC, and pure nuclear power plants is studied, and the level of CO2 emission tax effects on the cost of electricity from each plant is defined.
An advanced gas-cooled nuclear reactor in addition to a conventional NGCC as a heat source for the air exiting the compressor is considered. At a reactor outlet gas temperature of 900°C, the thermal contribution (fossil fuel saving and CO2 reduction) by nuclear energy in the nuclear-assisted NGCC cycle was 46.3%.
To assess the economic competitiveness of the plants, the levelized electricity generation costs were calculated. The economics depend primarily on the cost of natural gas and the capital cost of the nuclear reactor. Obviously, the best plant option for low natural-gas cost is pure NGCC and is pure nuclear power for high natural-gas prices. The intersecting points are affected by the assumed carbon tax.
Several synergetic effects for using nuclear and fossil powers together are quantified. First, since the electricity generation cost of the nuclear-assisted NGCC cycle is not as sensitive to gas price as the NGCC, the economic risk of fluctuations in gas prices can be minimized by adopting a nuclear-assisted NGCC cycle. Second, the high nuclear capital cost can be largely compensated for by the low capital cost of the gas turbine plant. For example, 3000 $/kW(electric) of nuclear capital cost can be effectively reduced to ~1500 $/kW(electric) for the hybrid plant. Third, nuclear-assisted NGCC has several advantages over the two single-fuel options in the reduction of high capital costs and high gas prices. In addition, the greenhouse gas emissions can be reduced by half by using nuclear-assisted NGCC, and the amount of nuclear spent fuel per kilowatt-hour would also be less than that of the pure nuclear option.