Yesterday the New York Times had an article on a new method of producing hydrogen from electrolysis using nuclear power (registration required). The new technique still is not a net production of energy, but it has drastically cut the amount of energy required to isolate the hydrogen:
The heart of the plan is an improvement on the most convenient way to make hydrogen, which is to run electric current through water, splitting the H2O molecule into hydrogen and oxygen. This process, called electrolysis, now has a drawback: if the electricity comes from coal, which is the biggest source of power in this country, then the energy value of the ingredients – the amount of energy given off when the fuel is burned – is three and a half to four times larger than the energy value of the product. Also, carbon dioxide and nitrogen oxide emissions increase when the additional coal is burned.
Hydrogen can also be made by mixing steam with natural gas and breaking apart both molecules, but the price of natural gas is rising rapidly.
The new method involves running electricity through water that has a very high temperature. As the water molecule breaks up, a ceramic sieve separates the oxygen from the hydrogen. The resulting hydrogen has about half the energy value of the energy put into the process, the developers say. Such losses may be acceptable, or even desirable, because hydrogen for a nuclear reactor can be substituted for oil, which is imported and expensive, and because the basic fuel, uranium, is plentiful.
The idea is to build a reactor that would heat the cooling medium in the nuclear core, in this case helium gas, to about 1,000 degrees Celsius, or more than 1,800 degrees Fahrenheit. The existing generation of reactors, used exclusively for electric generation, use water for cooling and heat it to only about 300 degrees Celsius.
The hot gas would be used two ways. It would spin a turbine to make electricity, which could be run through the water being separated. And it would heat that water, to 800 degrees Celsius. But if electricity demand on the power grid ran extremely high, the hydrogen production could easily be shut down for a few hours, and all of the energy could be converted to electricity, designers say.
The kicker here is, of course, building the type of nuclear reactor that would be able to serve such double duty. Perhaps if natural gas prices stay close to $7/mmBTU and oil stays above $40/barrel we’ll see the construction of new nuclear reactors.
Very interesting development.