“The New Age of Energy” trumpets the cover story in U.S.
News and World Report this week. Illustrating the revolution
is a photo of what looks like a carpenter’s level stuck in the
ground after just arriving from outer space.
In fact, it’s a real facility — the PS10 Solar Tower just
erected in Spain. Writes U.S. News editor Marianne
Lavelle in a breathless report:
Solar energy may be poised to make the leap from the
rooftop down to the floor of the desert — where some advocates say
it needs to be if it’s going to take its rightful place as a member
of Big Energy….Instead of using semiconducting material to
convert energy to sunlight — those familiar black photovoltaic
panels — [the new technology] will use nothing more complicated
than mirrors, lots of them, to concentrate some of the
highest-intensity sunlight in the world. The arrays will heat water
to drive turbines just as in an old-fashioned power
plant.
The Power Tower, in fact, produces only 11 megawatts — about 1
percent of a conventional utility plant. In order to do this it
occupies nearly one-fifth of a square mile.
The angle of the story, however, is that all this excitement has
attracted the interest of Silicon Valley. Vinod Koshla, a
co-founder of Sun Microsystems, and Google.org, the philanthropic
arm of Google, are all investing. “[This] vanguard of entrepreneurs
and financiers…believe their Silicon Valley success stories can
be repeated in green energy,” says Lavelle. “One estimate is that
venture capital funds nearly tripled their investment on green
energy last year, putting $2.4 billion to work.”
Invoking the Valley’s experience with microprocessors and
telecommunication, Koshla promises, “All the innovation came from
little companies that had breakthrough technologies….You should
have a thousand points of innovation and for sure you’ll get a
breakthrough.”
So are we headed for a future of clean, green energy funded by
Silicon Valley entrepreneurs? Don’t bet on it. If I were investing,
I’d short every one of these ventures.
HERE’S A LITTLE BACKGROUND.
In 1980, the Sandia National Laboratory, with the help of the
newly formed Department of Energy, erected Solar One, a central
electric power station, in the Mojave Desert near Barstow,
California. It consisted of an array of computer-controlled mirrors
focused the sun’s rays on a 15-story tower, which raised its
temperatures to 1500o C. The tower contained a synthetic
heat-transfer oil called “therminol,” which does not boil at 1500o
C but passes its heat on to water, which does. The steam drove a
turbine to produce 10 MW of electricity.
Solar One operated until 1988, when it was no longer deemed
practical. The flow of electricity was always interrupted when the
sun went behind a cloud. Over the next few years, however, the
facility developed a method for storing power in molten salts and
reopened in 1996. Solar Two sold electricity to the grid until
going offline again in 1999. The new tower in Spain — subsidized
by the government, of course — has almost the same dimensions,
occupying about one-fifth of a square mile to produce 11 MW. To get
to 500 MW — the size of a small commercial plant — it would have
to cover ten square miles.
When it became clear that Solar One had its limitations, DOE
funded a second facility, called the Solar Electric Generating
System (SEGS), built by the Luz Corporation. U.S. News
offers a nice description: “[S]ince the 1980s, a dazzling
‘parabolic trough’ display has provided reliable power to
California, the only operating concentrating solar power project in
the country.” The facility consists of 100 acres of 40-foot-high
parabolic mirrors that focus the sun’s rays on a small black tube
running along their focal point. The tube once again contains
therminol, which again heats to 1500o C, again producing steam. The
system is more efficient than the power tower, generating 354
MW.
The big problem is maintenance. The 10 million square feet of
mirrors have to be washed every five days and scoured by
high-pressure hoses once a month. The job is very labor-intensive.
Luz went bankrupt in 1991 but the project was soon revived under
the Public Utilities Regulatory Policies Act of 1978 (PURPA), which
allowed states to require that utilities buy electricity from
“alternate providers” no matter what the cost. California was an
enthusiastic participant.
SEGS was soon plagued by fires. On January 10, 1990, a series of
explosions rocked one of its cooling towers and ignited large
quantities of therminol. Thirteen engine companies needed 1500
gallons of foam to quench the flames. (UPI, “Explosions Rock Solar
Energy Plant,” January 10, 1990.) Then on February 27, 1999, almost
a million gallons of therminol caught fire, destroying considerable
portion of the facility. The flames released toxic fumes and a
half-square-mile area had to be evacuated. The Federal Aviation
Administration also set up a no-fly zone around the facility.
(“Authorities Evacuate Area After Blast at Solar Plant,” The
Associated Press, February 27, 1999.)
The good news is the system recovered and SEGS still operates
under California’s new “renewable portfolio” law, which requires
utilities to buy 10 percent of their electricity from renewable
sources. The bad news is this one facility represents 90
percent of the world’s solar thermal electric capacity. At
present there are no plans for its expansion.
Thus, we’ve already been around the block once with thermally
generated solar electricity. The irony is that in the 1990s solar
enthusiasts pretty much abandoned steam-generating solar power
stations as too old-fashioned. Instead, they embraced
photovoltaics, which offered “distributed power” that could be put
on every rooftop.
Photovoltaics utilize Einstein’s “photoelectric effect” — the
ability of a ray of light to knock loose an electron and start an
electric current. Each wavelength of light interacts with different
elements, however, and only a small portion of the sun’s energy —
about 20 percent — can be converted. Silicon has been chosen as
the material for photovoltaic “cells,” not because it is any better
than other elements — it is worse than some — but because it is
the cheapest as a raw material. Unfortunately, this has created the
impression that solar cells will go through a miniaturization
process, as computer chips have done. It can’t happen. Photovoltaic
cells can only be made bigger and more ubiquitous to capture more
solar energy.
Because there is no Moore’s Law for solar power, the price of
photovoltaic cells has not experienced the drops that are supposed
to come with mass production. As U.S. News puts it, “PV
cost estimates span from an uncompetitive 23 to 43 cents per
kilowatt-hour, while residential electricity prices in this country
range from 5.8 to 16.7 cents.” PV cells may eventually find a niche
in providing “peaking power” — the extra electricity needed by
utilities on hot summer days when everybody turns on the air
conditioning. But for base-load electricity, they will probably
never work — particularly since the electricity disappears when
the sun doesn’t shine.
It is because of the failure of photovoltaics to
provide conventional electricity that enthusiasts have now turned
back to the Power Tower.
SO WHAT ELSE IS PART of this “New Age of Energy?” U.S.
News also offers up “deep geothermal,” heat energy drawn from
deep within the earth.
Although not commonly recognized, the earth is a very hot place.
Temperatures at the molten core of the earth reach 7,000 degrees C,
hotter than the surface of the sun. In some regions, this molten
magma comes close enough to the earth’s surface to heat
groundwater. This produces geysers, geothermal vents (called
“fumeroles”), and other forms of steam and superheated water
jetting or leaking from the earth.
Since the 1980s, California, Hawaii and Iceland — all areas of
frequent volcanic activity — have attached steam turbines to some
of these vents to produce modest amounts of electricity. The
largest geothermal plants produce 75 megawatts (about one-twelfth
the size of a conventional plant). California now produces 2
percent of its electricity from geothermal and this represents 90
percent of America’s capacity and 25 percent of the world’s. There
are only so many potential sites and often they are tourist
attractions. So far no one has suggested attaching a power plant to
Old Faithful.
Recently the idea has developed, however, that if we pump water
deep into the earth — about three miles — it will heat to 300
degrees and can then be pumped to the surface again to produce
steam. A recent MIT study suggested that the nation could provide
all its electrical needs from this source.
The problem, once again, is cost. Even on paper, the MIT report
already has the price at running as high as $1.00 per kwh — about
ten times the price of conventional electricity. And that’s before
anybody has even tried it. Once again, deep geothermal will be one
of those far-fetched ideas that is always dangled as an alternative
to doing something in the here and now.
So here’s a suggestion. Instead of pumping water three miles
into the earth to heat it, why don’t we take the source of
that heat and bring it to the surface?
That’s what we do when we build a nuclear plant. The main source
of the earth’s heat is the radioactive breakdown of uranium and
thorium atoms. A nuclear reactor simply brings this process to the
surface and accelerates it under carefully controlled conditions.
Drawing on this terrestrial heat isn’t that much different from
burning the stored solar energy in coal — except that nuclear
reactions produce 2 million times as much energy per ounce without
any exhaust gases.
“Terrestrial energy” — it’s a “green” idea that didn’t make
U.S. News’s “New Age of Energy.” Somehow it hasn’t yet
made it into the environmentalists’ playbook, either. But if we’re
going to solve any of our energy problems — supply, pollution,
global warming — we’re going to have to give it a more serious
look.
