The California Public Utilities Commission (CPUC) has approved San Diego
Gas & Electric's (SDG&E) contracts to purchase 300 MW of solar power, with
the potential to grow to 900 MW within 10 years. The project will be one
of the largest solar facilities in the world when fully constructed and
the first commercial deployment of Stirling engine-based solar
concentrators.
SDG&E will purchase the solar energy from Arizona-based Stirling Energy
Systems. SDG&E and Stirling have agreed to a 20-year contract to first
purchase 300 MW from Stirling's SES Solar 2 facility, home to a series of
Stirling solar dishes to be developed on approximately three square miles
in Imperial Valley, Calif.
The Stirling solar dishes use a mirrored array to focus the sun's rays on
a modern Stirling engine. Stirling engines, originally developed in 1816,
have four sealed cylinders containing hydrogen or helium. When a cylinder
is heated by the sun, the gas expands and pushes a piston; when it cools,
the piston retreats. The mechanical action turns a generator and produces
electricity. Because the cylinders are sealed, Stirling engines do not
produce emissions.
SDG&E has options on two future phases that could add an additional 600 MW
of renewable energy and capacity to SDG&E's resource mix. Solar energy is
generally abundant during the hottest parts of the day, making it
available to meet peak demand from customers.
SDG&E said the Stirling projects will require additional transmission
facilities to be built to bring the energy to SDG&E customers. Just days
before this announcement, SDG&E filed with the CPUC explaining the need
for a major new transmission line stretching over 100 miles between the
San Diego region and the Imperial Valley -- by 2010. SDG&E said the
proposed transmission line would help to guarantee delivery of the full
potential of this solar contract. SGG&E estimates the line will cost $1
billion to $1.4 billion but that the exact costs will be determined once a
final proposed route and an alternate route are submitted to the CPUC in
mid-2006. There was no indication whether their involvement with this new
transmission line, which they're calling the Sunrise Powerlink, would be
accompanied by a CPUC request for approval of ratepayer increases.
"The CPUC's approval of our contracts is a win-win situation for our
customers and the communities we serve," said Terry Farrelly, vice
president of electric and gas procurement at SDG&E. "The project will
provide clean, renewable solar energy and move us closer to achieving our
goal to supply 20 percent of our customers' needs from renewable resources
by 2010."
