[ RadSafe ] Nuclear Reactors to Energy sources for Hydrogen

[John Jacobus]

>From IEE Spectrum Online: 
http://www.spectrum.ieee.org/WEBONLY/resource/mar05/0305nhyd.html
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Cheaper Hydrogen Beckons 

But where will we get the energy to make it? 

Energy systems using hydrogen could free us from
dependence on oil and from the threats of smog and
greenhouse gases. Yet three problems make hydrogen
prohibitively expensive: generating it from a clean
source, storing it, and moving it to wherever it's
needed. 

A solution to the first problem—the clean generation
of hydrogen—may be at hand. In November, researchers
at the DOE's Idaho National Engineering and
Environmental Laboratory (INEEL), in Idaho Falls,
found a better way to break water into hydrogen and
oxygen. They run fuel cells in reverse: instead of
turning hydrogen into electricity, they turn
electricity into hydrogen. And by doing so at 850 °C,
they get nearly twice the efficiency of the
electrolysis of water into hydrogen and oxygen. 

"We're taking high-temperature steam and electricity
and producing hydrogen," says Stephen Herring, the
lead researcher for this project. The solid-oxide
electrolysis cells, as they are called, are made by
Ceramatec Inc., of Salt Lake City, which develops
ceramic energy systems, especially fuel cells.  

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[Photo] Fire burn and cauldron bubble: Hydrogen
bubbles from an electrically heated electrolytic cell
at a U.S. Energy Department laboratory in Idaho. A
proposed commercial version would get its input heat
and electricity from a nuclear reactor. 
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The new method could offer advantages over the method
by which the United States now gets 95 percent of its
hydrogen: the re-formation of natural gas. "The
problem with [re-forming] is twofold," says Phil
MacDonald, a nuclear engineer at INEEL. "It releases a
lot of carbon dioxide into the atmosphere. Second, it
would put pressure on the price of natural gas that we
burn for our home heating." In addition, producing and
delivering hydrogen from natural gas costs about US $4
to $5 per kilogram. Since a kilogram of hydrogen has
the energy of a gallon (2.8 kg) of gasoline, this
process would cost about three times the present U.S.
retail price of gasoline. 

Electrolysis of water is currently even more
expensive, at about $7 to $9 per kilogram of hydrogen
produced. This means that the new method makes sense
only if the energy needed for electrolysis comes from
a cheap, non-carbon-emitting source. The only likely
candidate is a nuclear reactor, which would boil water
into steam. Some of the steam, heated to about 850 °C,
would be fed to one of the fuel cell's electrodes,
facilitating electrolysis; the rest would drive a
turbine that would turn a generator, powering the
cell. The plan requires a reactor that can run some
550 °C hotter than today's models, and that would mean
replacing metal components with ceramics or graphite
and cooling with helium gas instead of water. 

The DOE's plans for nuclear hydrogen are ambitious. By
2015, the goal is to demonstrate the first reactor
having a thermal output of 600 megawatts and producing
about 2.5 kg of hydrogen per second, at a cost of
$1.50 per kilogram. These reactors "would supply the
transportation needs of about a quarter million people
[a day]," Herring says. 

It doesn't seem likely to happen without a sea change
in public opinion. No one in the United States has
commissioned a new nuclear plant in 30 years, let
alone one based on a new design requiring a large
capital outlay. "It's not attractive economically...in
an uncertain pricing environment," says Joseph Romm,
former acting assistant secretary of energy and author
of The Hype about Hydrogen: Fact and Fiction in the
Race to Save the Climate (Island Press, Washington,
D.C., 2004). Besides, using nuclear energy doesn't
ease the hydrogen storage problem. A practical scheme
would make hydrogen close to where it will be used,
Romm says, and you can't do that with nuclear sources.
"You are going to be killed on the capital cost and
the transport cost," he says. 

To keep the dream of hydrogen alive, the INEEL
researchers talk of using it to refine low-grade
petroleum and make synthetic fuels. But if the goal is
to cut greenhouse gas emissions, why use the hydrogen
to refine petroleum? In fact, why make hydrogen at
all? If instead we used nuclear energy to replace
coal-fired power plants, it would save four times as
much in carbon dioxide emissions. And if the goal is
to reduce petroleum imports, Romm says, then hydrogen
can be made more efficiently from natural gas. 

Using nuclear power to make hydrogen is "a long
stretch," he says. "It's an idea whose time is not
likely ever to come." 

—Prachi Patel Predd 


+++++++++++++++++++
"A positive attitude may not solve all your problems, but it will annoy
enough people to make it worth the effort." Herm Albright

-- John
John Jacobus, MS
Certified Health Physicist
e-mail:  crispy_bird at yahoo.com


		
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