Full Title: A Nuclear Wind/Solar Oil-Shale System for Variable Electricity and Liquid Fuels Production
Author(s): Charles Fosberg
Publication Date: 6/2012
Length: 6 pages, PDF
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The recoverable reserves of oil shale in the United States exceed the total quantity of oil produced to date worldwide. Oil shale contains no oil, rather it contains kerogen which when heated decomposes into oil, gases, and a carbon char. The energy required to heat the kerogen- containing rock to produce the oil is about a quarter of the energy value of the recovered products. If fossil fuels are burned to supply this energy, the greenhouse gas releases are large relative to producing gasoline and diesel from crude oil.
The oil shale can be heated underground with steam from nuclear reactors leaving the carbon char underground—a form of carbon sequestration. Because the thermal conductivity of the oil shale is low, the heating process takes months to years. This process characteristic in a system where the reactor dominates the capital costs creates the option to operate the nuclear reactor at base load while providing variable electricity to meet peak electricity demand and heat for the shale oil at times of low electricity demand. This, in turn, may enable the large scale use of renewables such as wind and solar for electricity production because the base-load nuclear plants can provide lower-cost variable backup electricity.
Nuclear shale oil may reduce the greenhouse gas releases from using gasoline and diesel in half relative to gasoline and diesel produced from conventional oil. The variable electricity replaces electricity that would have been produced by fossil plants. The carbon credits from replacing fossil fuels for variable electricity production, if assigned to shale oil production, results in a carbon footprint from burning gasoline or diesel from shale oil that may half that of conventional crude oil. The U.S. imports about 10 million barrels of oil per day at a cost of a billion dollars per day. It would require about 200 GW of high-temperature nuclear heat to recover this quantity of shale oil—about two-thirds the thermal output of existing nuclear reactors in the United States. With the added variable electricity production to enable renewables, additional nuclear capacity would be required.