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Power
Larger
Solar Projects Gain Ground as Technology Improves
(enr.construction.com - 04/19/04 issue)
By Paul
Rosta
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| ON THE
TOP The 60,000-sq-ft rooftop solar array on Moscone Center
is part of San Francisco’s program to use only pollution-free
power. (Photo courtesy of Power Light) |
Long a small-scale darling of green-energy
advocates, solar power recently has been bulking up with announcements
of several high-profile, large-scale projects. While solar
still appears to be years away from competing with conventional
generation, innovation and steadily falling prices are speeding
up the timetable.
"The cleanliness of the resource"
is one of solar’s appeals, says Peter Johnston, manager
of technology development at Arizona Public Service Co., Phoenix,
the state’s largest electric utility. APS announced plans
last month to build a 1-MW solar trough plant, the first of
its kind in the U.S. since 1988. Raleigh, N.C.-based SolarGenics
LLC will install the equipment at APS’ Saguaro powerplant
in Red Rock, Ariz., about 30 miles north of Tucson. The plant
is scheduled to come on line by April 2005 at a cost of $5
million to $6 million.
At the Saguaro plant, parabolic mirrors
will concentrate sunlight and heat mineral oil to between
250° and 500°F. Flowing through a heat exchanger,
the heated oil will vaporize pentane, a hydrocarbon, which
in turn will drive the turbine. The vapor then will condense
back into liquid form and the cycle will repeat.
This approach represents a departure
from existing solar thermal plants, which turn turbines with
superheated steam. "If you’re working with superheated
steam, you need a big plant," requiring a $150-million
to $200-million investment, says Johnston. Instead, APS will
use a 1-MW turbine similar to a geothermal plant’s.
Widespread use is "more a question
of investor confidence than further technological development,"
says Terry Peterson, manager of solar and green power marketing
at the Electric Power Research Institute, Palo Alto, Calif.
A commercial-size plant needs investors with deep pockets
"and pretty cold blood and they haven’t been stepping
forward," he says.
As solar thermal awaits further investment,
photovoltaic panels are drawing interest. PowerLight Corp.,
Oakland, Calif., recently completed a 675-kW, $7.4-million
installation and energy-efficiency upgrade at San Francisco’s
Moscone Center. In March, Alameda County, Calif., supervisors
gave PowerLight the go-ahead for a 1.1-MW, $4.8-million program
spread among six county buildings. And Sun Power & Geothermal
Energy Inc., San Francisco, is installing an $8.4-million,
1-MW solar array for Butte County to power two jails and the
county administration building. Interest also continues among
smaller commercial and residential installations, industry
officials say.
Like other renewables, photovoltaic
systems need government subsidies to be attractive to customers.
"If the incentives weren’t there, then savings wouldn’t
be enough to pay for the project," says Matt Muniz, energy
program manager for Alameda County. Yet prices have dropped
significantly, from about $4.50 to $3.83 per Watt installed,
including incentives, says Muniz.
Costs should fall by another 50% over
the next half-dozen years, says Dan Shugar, PowerLight’s
president. "This market, by the end of the decade, will
need very little by way of incentives to make this technology
happen," he predicts. Shugar says initial capital costs
for large solar photovoltaic systems run between $6,000 and
$8,000 per kW. The Moscone project costs exceed that because
an energy efficiency upgrade is included in them.
One potential record-setter faces opposition.
Southern California Edison announced plans last December for
a 5-MW plant near Barstow, Calif., that it claims would be
the world’s largest central solar photovoltaic station.
Critics argue that SCE’s procurement, which resulted
in the selection of Pasadena-based TrueSolar Solutions LLC,
was not competitive and that the project would drain $60 million
from the state fund that provides financial incentives for
renewable technology, says Matt Freedman, an attorney for
The Utility Reform Network, a San Francisco-based consumer
group. Freedman believes the central station concept is outmoded
and that solar photovoltaics are best suited "for distributed
generation, not for covering the desert."
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