ATTRIBUTES OF A NUCLEAR-ASSISTED GAS TURBINE POWER CYCLE

Abstract

By using a combination of a nuclear reactor, which emits no carbon dioxide, and a high efficiency natural gas turbine combined cycle (NGCC), electric utilities can reduce their generation cost as well as minimize the greenhouse gas emissions. In this work, the economic competitiveness of pure NGCC, nuclear assisted NGCC and pure nuclear power plants are studied. An advanced gas cooled nuclear reactor can be added to the conventional NGCC as a heat source for the air exiting the compressor. For this study we assumed a high temperature pebble bed modular reactor (PBMR) with reactor outlet gas temperature of 900ºC. With that temperature, the thermal contribution (fossil fuel savings and CO[subscript 2] reduction) of nuclear energy in the nuclear-assisted NGCC cycle was 46.3%. For assessing the economic competitiveness of the three options, the levelized electricity generation costs were calculated. The economics depend on the cost of natural gas and the capital cost of the nuclear reactor. Obviously, the best option for low natural gas cost is the pure NGCC, whereas the pure nuclear power is the best choice for high natural gas prices. The crossing points vary depending on the level of expected carbon tax. The pure nuclear option is not affected by the level of carbon tax. The nuclear-assisted NGCC cost is in the middle. There are several synergetic effects to using nuclear and fossil powers together. First, since the generation cost of the nuclear-assisted NGCC cycle is not as sensitive to the gas price as the NGCC, the economic risk of an NGCC plant can be minimized by adopting a nuclear-assisted NGCC cycle. Second, by introducing NGCC to nuclear power, the risk from high nuclear capital cost can be mitigated. For example, 3000 $/kW[subscript e] of nuclear capital cost can be reduced to about 1500 $/kW[subscript e]. Third, in addition to minimizing the risk from gas price fluctuation and high capital cost, even though the window is very narrow, the nuclear assisted NGCC can be more advantageous over the other two options in case of high nuclear capital costs and high gas prices. Finally, green house gas emissions can be reduced significantly using nuclear assisted NGCC.