|Nuclear reactors and ethanol plants in the Corn Belt. Click to enlarge.|
Researchers and engineers at Oak Ridge National Laboratory and the US Department of Energy are suggesting using the steam from existing nuclear power plants in the Corn Belt to reduce the costs of producing ethanol from corn and other biomass.
While current corn-to-ethanol plants provide the near-term market for nuclear steam, future cellulose-to-ethanol plants represent a much larger and longer-term market for nuclear steam. The ethanol market could require hundreds of gigawatts of thermal energy and thus may become the dominant cogeneration market for nuclear heat, according to the authors of a paper on the topic to be presented at the upcoming International Conference on Non-Electrical Applications of Nuclear Power.
The cost of low-pressure steam from nuclear power plants is less than that of natural gas, which is now used to make steam in corn-to-ethanol plants. The use of steam from nuclear power plants reduces greenhouse gases compared with the generation of steam from fossil fuels. Last, in cellulose-to-ethanol plants the liquid fuel produced per unit of biomass can be substantially increased if the ethanol plants also have the capability to convert lignin to liquid fuels. Lignin is the primary non-sugar-based component in cellulosic biomass that can not be converted to ethanol. It is planned to use this lignin as boiler fuel in these ethanol plants; however, if there are other sources of steam it may be feasible to also convert the lignin to liquid fuels and thus increase the yield of liquid fuels per unit of cellulosic biomass. In several decades, this market may become the largest market for cogeneration of steam from nuclear electric power.—from “Fuel Ethanol Production Using Nuclear-Plant Steam”
Although the concept of using steam from nuclear power plants in ethanol production is not new, up until recently the economics and the scale of ethanol production were not particularly compelling.
From a lifecycle perspective, the greenhouse gas releases from consuming fossil fuels—from growing the corn through the conventional production of ethanol—are only about 20% less than from the alternative of producing gasoline from crude oil with an equivalent energy value, according to the authors.
If nuclear energy is used to support ethanol production, however, fossil fuel inputs can be dramatically reduced. The conversion of corn to ethanol primarily requires low-quality, low-cost steam—something nuclear power plants are very good at producing. Using low-quality steam from nuclear power plants in the corn-to-ethanol production process would reduce fossil fuel inputs and the resultant greenhouse gas emissions for the entire process of growing the corn and converting it to ethanol by almost half.
Steam provided by the reactor would be condensed at the ethanol plant, and warm water would be returned to the nuclear power plant. Almost all of the heat required by the production process could come from condensing the steam. Modern steam systems would allow more than a mile of separation between the reactor and the ethanol plant.
Based on the price of electricity, the cost of low temperature steam from a nuclear power plant is about half the cost of steam from natural gas.
(A hat-tip to Charles!)
Producing ethanol from corn using nuclear-generated steam (Nuclear News)
“Fuel Ethanol Production Using Nuclear-Plant Steam”;Charles W. Forsberg, Samuel Rosenbloom, Richard Black; IAEA Conference/Paper Number: IAEA-CN-152-47