No subject

Scott Kair

----- Original Message -----

Hydrogen fuel cells may harm ozone
Scientists warn about potential for leaks to occur
Carl T. Hall, Chronicle Science Writer
Friday, June 13, 2003
=A92003 San Francisco Chronicle | Feedback

URL:
http://www.sfgate.com/cgi-bin/article.cgi?file=3D/chronicle/archive/2003/06=
/13
/MN296207.DTL

The vision of a clean, green hydrogen economy may have just sprung a leak.

Scientists at the California Institute of Technology in Pasadena report
today that widespread use of hydrogen fuel cells to power everything from
cars to power plants could indirectly deplete the ozone layer that protects
against ultraviolet radiation.

The "hitherto unknown environmental impacts" might also include enigmatic
"noctilucent clouds" that would shine at night far above the planet's
surface, fundamentally changing the way sunlight is absorbed and reflected
by the Earth, the Caltech scientists report in the journal Science.

Hydrogen fuel cells have been touted as an environmentally friendly,
pollution-free solution to the world's energy needs.

President Bush, for instance, has made hydrogen fuel cells the centerpiece
of a $1.2 billion clean-car initiative, claiming fuel cells would generate
"effectively zero emissions," the only waste product being water.

But in the report released today, the Caltech scientists say that if
hydrogen were used as the main energy source, it would leak during
production, distribution and storage on a much larger scale.

How much leakage might occur is anyone's guess, but the Caltech researchers
speculate it could be substantial: 60 trillion to 120 trillion grams a
year, or four to eight times current hydrogen emissions due to human
activity.

Counting the hydrogen already emitted by volcanoes and other natural
sources, the total amount of free hydrogen in the atmosphere would double
or triple. The amount could be reduced somewhat by leak-proofing the
hydrogen infrastructure -- which doesn't exist as yet -- but it's unclear
how well such technology would work and how much it might cost.

Any big increase in runaway hydrogen could wreak havoc in the upper layers
of the atmosphere, reacting with oxygen to produce water vapor where it's
normally clear and dry. Chemical reactions would be similar to those
attributed to leaks of ozone-depleting chlorofluorocarbons, or CFCs, from
old refrigerators and air conditioners.

A complete switch from fossil fuels to a hydrogen-based energy system might
lead indirectly to something on the order of a 10 percent reduction in
atmospheric ozone and an 8 percent widening of the ozone holes at the north
and south poles, the Caltech scientists report.

There would be some obvious benefits, too, including much less soot and
smog in urban areas. An estimated 30,000 deaths a year in the United States
are blamed on toxic gases and other noxious byproducts of burning
conventional fuels.

In a telephone interview, study co-author and Caltech assistant professor
of geochemistry John Eiler conceded that a move away from fossil fuels
would hardly be an environmental calamity on most counts. But he said the
trade-off might be more skin cancer from UV radiation at higher latitudes.

"This is not the central issue in discussions of a hydrogen economy, but
you don't want to decide at the very beginning that a whole set of things
like this don't matter," Eiler said.

He said the best way to minimize any hazard would be to design effective
safeguards now -- long before hydrogen fuel cells enter widespread usage.

"In no way should this be misconstrued as putting a hole in the hull" of
the hydrogen economy, Eiler said. "It's an attempt to illuminate some
potential pitfalls. We should start thinking about it now."

Other experts agreed that the prospect of a leaky hydrogen economy is no
laughing matter.

"It should be taken seriously, seriously enough so that more work like this
is funded and we understand in more detail what kind of problem this might
be, " said Anthony Wexler, an environmental scientist at UC Davis. "There's
no question that this is worth exploring further."

E-mail Carl T. Hall at chall at sfchronicle.com.