Cheap Hydrogen Fuel

 

Cheap Hydrogen Fuel
GE says its new machine could make the hydrogen economy affordable, by
slashing the cost of water-splitting technology.

By David Talbot

Among the many daunting challenges to replacing fossil fuels with
hydrogen is how to make hydrogen cheaply in ways that don't pollute the
environment. Splitting water molecules into hydrogen and oxygen using
electricity from energy sources such as wind turbines is one
possibility -- but it's still far too expensive to be widely practical.



Now researchers at GE say they've come up with a prototype version of
an easy-to-manufacture apparatus that they believe could lead to a
commercial machine able to produce hydrogen via electrolysis for about
$3 per kilogram -- a quantity roughly comparable to a gallon of
gasoline -- down from today's $8 per kilogram. That could make it
economically practical for future fuel-cell vehicles that run on
hydrogen.


Electrolyzers are fairly simple technologies: water is mixed with
potassium hydroxide electrolyte and made to flow past a stack of
electrodes. Electricity causes the water molecules to split into
hydrogen and oxygen gases, which bubble out of the solution. The
chemistry makes a good high-school science experiment -- but
commercial-scale quantities of hydrogen are extracted far more cheaply
from natural gas.


The core problem in improving electrolyzers for hydrogen manufacture is
not how to improve the fundamental conversion efficiency, says Richard
Bourgeois, an electrolysis project leader at GE Global Research in
Niskayuna, NY. "You can only make it so much more efficient; there
isn't a lot you can do. So we've attacked the capital costs," he says.


Today's electrolyzers are made of metal plates bolted together
manually, with gaskets between them, and the whole unit is typically
housed in a chamber made of the same metals used in the electrodes,
says Bourgeois. The materials are expensive and assembly requires
costly labor.


Bourgeois' research team came up with a way to make future
electrolyzers largely out of plastic. They used a GE plastic called
Noryl that is extremely resistant to the highly alkaline potassium
hydroxide. And because the plastic is easy to form and join,
manufacturing an electrolyzer is relatively cheap.


Inside the plastic housing, metal electrodes still do the same job. But
because GE is using less electrode material, the reactivity of the
electrodes' surfaces is improved. To do this, the researchers borrowed
a spray-coating process -- normally used to apply coatings for parts on
jet engines -- to coat the electrodes with a proprietary nickel-based
catalyst with a large surface area.


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<snip>
Even if all this were true (and I doubt whether the capital cost of
the electrolysers is a big problem) - it doesn't answer the more
fundemental problems of how you store "a kilogram of hydrogen", or
where you obtain all the electrical energy to do the electrolysis. Nor
even how you are going to convert the world's fleet of vehicles from
petroleum-based to fuel cell/ hydrogen based.

My tuppence worth

Eric

(PS Does anyone have figures on the approximate efficiency of present
electrolysers that are in use commercially? By efficiency, I mean in
terms of the actual quantity of hydrogen produced by a given quantity
of electricity, compared with the theoretical amount).