Lots of good reading material on fuel cells in MIT's Technology Review Magazine.
technologyreview.com
Fuel Cells in Brief
By Alan Leo February 5, 2002
There’s a power revolution coming, and it
will run on hydrogen.
Fuel cells use chemical reactions to produce electricity from hydrogen
fuel (some start with compounds such as methanol and then extract
the hydrogen). Unlike batteries, which store a fixed amount of energy,
fuel cells can produce power as long as they are supplied with fuel.
Today, the world buys several hundred million dollars worth of fuel cells
each year to provide power generation for utilities, buildings, spacecraft
and industrial machinery. As the technology improves, fuel cells are
predicted to overtake batteries in many applications, from backup
power to mobile electronics.
And the fuel cell industry is chasing an even bigger target: the internal
combustion engine. After a century of refinement, the engine in your
car is still only 25% efficient—that is, only a quarter of the energy
stored in its fuel is converted to useful work. Fuel cells, on the other
hand, convert nearly fifty percent of their hydrogen fuel into
electricity—with the potential for further improvement. And where the
internal combustion engine coughs out a cloud of smog, hydrogen fuel
cells produce only water.
But many challenges stand in the way of fuel cell cars, including how to
increase cells' durability, reduce their cost, and improve fuel storage.
The greatest challenge may be to create an infrastructure to extract
and deliver the hydrogen fuel. Last month, the Department of Energy
announced a new effort to tackle these challenges with government
and industry research into automotive fuel cells.
Fuel cells work by harnessing the chemical attraction between oxygen,
which is taken from the air, and hydrogen, which is stored in a tank, to
produce electricity. A catalyst pries apart hydrogen atoms into a
positive ion and electron. The positive ions pass through a membrane to
bond with the oxygen; the electron travels around the membrane and
through a circuit, generating electrical current. On the other side of the
membrane, the oxygen, hydrogen ions and electrons form water.
Because hydrogen is difficult to store and transport, some fuel cells are
designed to use methanol or other hydrocarbon fuels, and work by
extracting the hydrogen. But these designs aren't as efficient, and they
emit carbon dioxide as well as water.
In Technology Review
In November 2000, TR contributor Peter Fairley mapped the road to fuel
cell cars in "Fill 'er Up with Hydrogen." He discussed current efforts by
carmakers, their alliances with fuel cell suppliers, and the challenges
they face.
In April 2001, two TR stories documented fuel cell breakthroughs: the
first, the Prototype "Fuel Cells Clean Up," highlighted a
fuel-cell-powered vacuum cleaner; the second, "Building a Better Fuel
Cell" by technologyreview.com staff editor Alan Leo, detailed efforts at
Caltech to improve on fuel cell membranes.
In March 2001, Fairley returned to the subject of fuel cells in "Power to
the People," a look at fuel cells and a new generation of distributed
generators called microturbines. As backup systems in many commercial
buildings today, these technologies appeal to customers who need
power that is resistant both to failure and to fluctuation.
But big installations are only part of the fuel-cell story, reports TR
contributor David Voss in November 2001's "A Fuel Cell in Your
Phone." Companies are racing to shrink fuel cells for mobile electronics,
and several partnerships have already developed prototype fuel-cell
phones.
In January 2002's "Fuel Cells vs. the Grid," TR contributor David
Freedman examined the fuel cell's potential to compete with the power
grid. Backup power, he writes, will be fuel cells' killer app--paving the
way for longer term advances such as the fuel cell car.
Which brings us back to the Energy Department's announcement last
month that it would boost research into automotive fuel cells. The
initiative, called FreedomCAR, will support fuel cell projects at
government labs, and encourage research by the Big Three automakers.
In January's "FreedomCAR: Will It Drive?" technologyreview.com's Leo
asks the experts what the plan will mean for auto research.
Powerful History
In 1839, Welsh chemist William Grove took a step backwards. It was
well known that adding electricity to water would separate its
component elements, oxygen and hydrogen—a process known as
electrolysis. By the same logic, Grove figured, there must be a way to
reverse the process: to join oxygen and hydrogen to produce water
and electricity. His experiment worked, and the fuel cell was born. But
fuel cells sat on the shelf for more than 100 years, little more than a
laboratory curiosity.
That changed in the 1960s, when the U.S. space program needed a
renewable power source for its Gemini spacecraft. It turned to a new
fuel-cell technology, the proton exchange membrane, which
dramatically increased the amount of energy captured from the
hydrogen-oxygen reaction.
Today, that technology is vying to be the next great power revolution:
clean, decentralized energy, powered by hydrogen.
Alan Leo is a staff editor at technologyreview.com |
