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Sempra Generation will turn up juice with expansion of solar-power plant
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Pangea on 10/12/2009 22:00:00
 
The dust had barely settled at the company's 5-month-old 10-megawatt
photovoltaic power generation plant near Boulder City, about 40 miles southeast
of Las Vegas, when it announced plans for an expansion to quintuple capacity. It
will create North America's largest thin-film photovoltaic installation with
enough power for 36,400 homes, the company claims. Nevada's 320 days of sunlight
a year and its broad expanses of undeveloped raw land make it an ideal location
for commercial photovoltaic power installations.
"This would be our largest renewable energy project thus far and move us closer
to our stated goal of becoming the first U.S. company to own 500 megawatts of
solar power," said Sempra Generation President and Chief Executive Officer
Michael Allman in a statement.
Renewable energy is in high demand. California wants renewable energy to make up
33 percent of its power consumption by 2020. Sempra Generation, a unit of San
Diego-based Sempra Energy, last year signed a 20-year power purchase agreement
with San Francisco-based Pacific Gas and Electric for the existing facility's
full output; it has yet to secure buyers for the addition.
"We won't start construction until we have a contract in hand," Sempra spokesman
Art Larson said. "We're talking to a number of utilities and potential customers
to gauge their interest in the facility. We hope to start construction later
this year."
Buyers could come from California and also Arizona, which seeks a 25 percent
renewable benchmark by 2025. Nevada similarly wants 20 percent of its power to
come from renewable resources by 2025, with 5 percent originating from solar.
Sempra's existing facility, El Dorado Solar Energy, rests on 80 acres of desert
land ground-leased from Boulder City for 20 years. It's next to parent Sempra's
480-megawatt natural gas-fired, combined-cycle El Dorado Energy power plant that
opened in May 2000, which means transmission lines are already in place. The
installation consists of 167,000 thin-film photovoltaic panels mounted to
stationary space frames anchored by light-gauge steel pilings. First Solar Inc.,
which built the original facility, is returning for the expansion. The Tempe,
Ariz.-based company will serve as engineering, procurement and construction
contractor, and oversee its operations when complete.
Plans call for another 830,000 thin-film photovoltaic panels, generating 48
megawatts, on 380 acres designated as a renewable energy zone by Boulder City.
The project will create about 200 construction jobs. Panels measure 3.6 feet
long by 2 feet wide and weigh 26.5 pounds; there are 15 panels per frame.
Construction entails drilling 100,000 pilings. Sempra is self-financing the
project and did not disclose costs; it's also taking advantage of a 30 percent
federal investment tax credit. The combined 58-megawatt, 997,000-panel facility,
renamed Copper Mountain Solar, is expected to begin service by late 2010.
"Thin films are about 50 percent less efficient than conventional silicon solar
panels, and require twice as much space to generate the same amount of power,"
said Joe Verrengia, a spokesman with the National Renewable Energy Laboratory in
Golden, Colo. "The potential advantage lies in reducing materials and
manufacturing costs."
First Solar uses cadmium telluride and sulfide semiconductor material with an
assembly-line production process that lowers manufacturing costs to 93 cents a
watt. It's roughly half the production cost of silicon panels, say company
officials. Panels, which have a 25-year life span, can be produced within 2.5
hours. They yield a 10.9 percent conversion rate from sunlight into energy.
Acciona, by comparison, achieves a 25 percent conversion rate at its 64-megawatt
solar power plant, which is also near Boulder City. The 2-year-old Nevada Solar
One facility uses concentrating solar thermal technology. Roughly 190,000 curved
parabolic mirrors concentrate sunlight to 750-degrees Fahrenheit to heat
synthetic oil inside tubes that create steam and drive turbines to produce
electricity. Acciona currently has a 40-year ground lease with Boulder City to
occupy 350 square acres in the Eldorado Valley. The city receives about a $1
million annually in rent payments between Acciona and Sempra.
PowerLight, meanwhile, achieves a 25 percent conversion rate at its 14-megawatt
photovoltaic installation at Nellis Air Force Base. The Solar Star facility,
opened in 2007, uses 72,000 photovoltaic monocrystalline wafer panels containing
nearly 6 million solar cells. It uses a tracking technology that rotates
photovoltaic panels throughout the day to follow the sunlight. Solar Star
consequently achieves a conversion rate that is 10 percent higher than the
industry average, PowerLight CEO Thomas Werner claims.
Photovoltaic film, however, like the kind found at El Dorado Solar Energy, is
lightweight and can be manufactured in large quantities using methods similar to
newspaper printing, officials say. Panels use layers of layers of semiconductor
materials only a few micrometers thick; they require only a tiny fraction of the
materials found in conventional cells. It makes thin film cheap, quick and easy
to mass-produce.
"Researchers and manufacturers are looking at each step in the process to
squeeze efficiencies, boost scale and go faster," Verrengia said. "Thin films
also can be manufactured in more conventional industrial conditions. And rather
than being built into rigid panels, they can be incorporated onto inexpensive
and conventional building materials such as glass or metal. This integrated
approach also has aesthetic advantages because the thin films can be installed
flush into roofs, windows and walls."