Fuel Ethanol Production Using Nuclear-Plant Steam

In the United States, the production of fuel ethanol from corn for cars and light trucks has increased from about 1.6 billion gallons per year in 2000 to 5 billion gallons per year in 2006. It is projected by 2030 that up to 30% of the liquid fuels consumed in the United States could be made from biomass [1, 2] with an ultimate production capability twice as large. Long-term studies [3] indicate that biofuels could provide about 30% of the global demand in an environmentally acceptable way without impacting food production. Rapid expansion of liquid fuels production from biomass is predicted for many other parts of the world as well. Sugarcane and corn are the primary feedstocks today, but future plants are expected to also use abundant cellulose. The rapid growth in biomass-to-ethanol plants is a result of three factors: new biotechnologies that are dramatically improving the economics; increased concern about global warming, which generates renewed interest in renewable liquid fuels; and the high cost of oil. The production of fuel ethanol from biomass requires large quantities of steam. For a large ethanol plant producing 100 million gallons of fuel ethanol from corn per year, about 80 MW(t) of 150-psi (~180oC) steam is required. Within several decades, the steam demand for ethanol plants in the United States is projected to be tens of gigawatts, with the worldwide demand being several times larger. There are strong incentives to use steam from nuclear power plants to meet this requirement. 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 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 in several decades the largest market for cogeneration of steam from nuclear electric power plants.