Thursday, August 5, 2010

Committee Endorses Giant Ivanpah Solar Power Plant in Mojave Desert

A proposed large-scale solar thermal power plant in California's Mojave Desert has moved another step closer to construction.

A siting committee of the California Energy Commission has recommended approval of plans for the Ivanpah Solar Electric Generating System, which would be built next to a flat, dry, ancient lakebed about 4.5 miles from the gambling resort of Primm, Nev.

The solar plant would generate power by a method unrelated to the solar photovoltaic technology that converts sunlight directly into electricity. Ivanpah would use broad fields of mirrors called heliostats to focus heat from the sun on three 459-foot-tall "power towers." The heat would be used to create steam that would drive turbines to generate electricity, as in a conventional power plant.

The project would contain as many as 173,500 heliostats, each holding two mirrors. Each mirror would be about 7-by-10.5 feet. The solar power plant is to be built on 3,582 acres of public land administered by the federal Bureau of Land Management. The development and construction cost is estimated at $1.1 billion. The plant's developers have received a loan guarantee for up to $1.37 billion from the U.S. Department of Energy.

Most of the water used for solar thermal power plants goes to cooling. The Ivanpah plant would be "dry-cooled," reducing its expected water usage to about 100 acre-feet a year. Natural gas would be used to heat the steam boilers more quickly each morning, and also are to be turned on when passing clouds obscure the sun. The natural-gas system would not be able to generate electricity at night or during periods of prolonged cloudiness.

The Ivanpah solar plant is to be built about 1 to 4 miles off Interstate 15, the highway that carries traffic between the Los Angeles area and Las Vegas. "Viewer numbers on this segment of highway are extremely high, particularly on Friday evenings and other peak periods, although the recreational destination for the majority of such motorists is Las Vegas rather than the Mojave Desert and the level of concern with scenic quality thus likely to be moderate or low," the siting committee's proposed decision said.

Construction of the solar plant would likely begin this fall and be completed in three phases by the fall of 2014. During the construction period, an average of about 460 workers would be employed on the project. The completed plant would have about 90 full-time workers.

The Ivanpah project's nominal peak solar generating capacity in the approved configuration would be about 370 megawatts. An existing high-voltage electricity line passes by the site. Some connecting lines and a large new substation would be built. About 36 miles of existing high-voltage lines in California and Nevada would also have to be upgraded, the California Energy Commission's document says.

The electricity would go into the grid system operated by Southern California Edison Co., and the power plant has an estimated working lifetime of at least 50 years. The electricity would be divided between SCE and Pacific Gas and Electric Co; between them, the two utilities cover much of the state.

"Although the project, even with the mitigation measures described in this decision, will have remaining significant impacts on the environment, the commission has found that the benefits the project would provide override those impacts," the proposed decision for approval says. "In addition, the commission has determined that the ISEGS project complies with all applicable laws, ordinances, regulations, and standards."

A 370-megawatt solar power plant, if built today, would be the largest in the world. However, by the time the Ivanpah plant is completed, if it receives final approvals and construction begins later this year, it is likely that one or more solar photovoltaic power plants exceeding its capacity will have been built. Solar PV plants can be constructed faster than a plant using the technology to be deployed at Ivanpah.

The developer of the project is Oakland, Calif.-based Brightsource Energy.

The project would be built in San Bernardino County, whose Board of Supervisors has expressed concern about whether county residents would benefit from the jobs created. The project site is closer to cities and towns in Nevada than California.

The proposed approval by the three-member siting project committee is not the final decision on the project. A full vote of the five-member Energy Commission is needed for a license to be issued. The Bureau of Land Management also has not yet approved the project.


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