Nuclear Energy for Simultaneous Low-Carbon Heavy-Oil Recovery and Gigawatt-Year Heat Storage for Peak Electricity Production

Abstract

In a carbon-constrained world or a world of high natural gas prices, the use of fossil-fueled power plants to satisfy variable electricity demands may be limited. Nuclear power plants operating at full capacity with large-scale energy storage systems could be employed to provide variable intermediate and peak electricity production. One storage option is to use a nuclear-geothermal system for peak electricity production. At times of low electricity demand, heat from a nuclear reactor in the form of pressurized hot water is used to heat underground rock. At times of high electricity demand, the reactor produces electricity. In parallel, cold pressurized water is injected into the bottom of the manmade hot-rock heat source, hot pressurized water is recovered, and the hot pressurized water is used with a geothermal power plant to produce peak electricity. A nuclear geothermal system for peak electricity production is a new concept with many possible configurations. This paper is an initial assessment of converting heavy oil reservoirs with a history of oil production into nuclear-geothermal systems for peak electricity production. Heavy oil is recovered by steam injection into a reservoir and raising the temperature so the heavy oil can flow to production wells. Such a reservoir may be economically attractive for conversion into a nuclear-geothermal peak electricity system because (1) the reservoir has been preheated to high temperatures that would minimize long-term heat losses from a nuclear geothermal system, (2) such geologies are likely to have reasonable permeability to water flow—a requirement for a nuclear-geothermal system, (3) much of the infrastructure is in place, and (4) the local geology is well understood—including effects of adding heat to the rock. The use of a heavy oil field as a nuclear-geothermal peak power system may significantly increase the fraction of heavy oil that is recovered and enable heavy oil recovery from deeper heavy-oil reservoirs. Total recoverable heavy oil resources may be significantly increased. The nuclear-geothermal heat storage facility acts like a washing machine on the heavy oil reservoir over time with oil extracted using the hot pressurized water. The reservoir characteristics (high porosity, etc.) for heat storage would be expected to improve as more oil is removed. The assessment is that this option is potentially attractive but there are significant uncertainties. The next step must include detailed studies of specific sites to develop a realistic understanding of the option.