August 17, 2007

Nuclear reactor steam can lower the cost of ethanol

Steam from nuclear plants could find a significant market by using it for ethanol production

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

There is one economic limitation, however. The cost of the corn delivered to a fuel ethanol plant is strongly dependent upon the cost of transporting the corn from the farm. The only nuclear reactors that can economically provide steam for this application are in the Corn Belt, along the Mississippi River or other waterways where cheap barge transportation is available, or where there is a demand for the by-products of ethanol production.

For a large ethanol plant producing 100 million gallons of fuel ethanol per year, about 80 MWt of steam is required, which represents a potential market for 150-psi (about 180 °C) steam from existing light-water nuclear power plants. This low-temperature steam is of lower value for electricity production, but it could significantly improve ethanol economics, create an expanded market for nuclear energy, reduce greenhouse gas emissions, and reduce foreign oil imports.

For about a decade, steam produced by the Bruce nuclear power station in Ontario was used for ethanol production. Plants in Switzerland and Russia produce both electricity and district heat.

The steam from nuclear reactors has been used for district heating (45 reactors), desalination (10 reactors), and industrial uses (25 reactors). Coproduced steam, however, has never been a major product of nuclear reactors for two reasons: (1) There are few customers near rural nuclear plant sites, and (2) most of the markets for steam are so small as to not be worth the complications of coproducing steam and electricity. The production of fuel ethanol from corn today, and the future production of fuel ethanol from other forms of biomass, change this. The need is for large quantities of steam in rural areas—the same areas in which nuclear power plants are located.

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. Last, ethanol plants traditionally operate at constant production but have the potential to shift some of the steam demand to nighttime. The largest use of energy in the ethanol production process is for distillation, which must operate at steady state. However, the energy demand for drying the animal feed by-products could potentially be shifted to nighttime.

A goal of the U.S. government is to displace 30 percent of the nation’s gasoline
use by 2030, initially by using corn, and then cellulose, for the production of
ethanol. That is an extraordinary challenge that requires increasing ethanol production by more than an order of magnitude. For this scale of operation, the total steam demand at a few hundred plants would be tens of gigawatts.

Congratulations! Now you can use SolidOpinion commenting system in all its magnificence! Click the link to get your password.

Форма для связи

Name

Email *

Message *