Tuesday, November 08, 2011

Space shuttle data leads to better model for solar power production in California

The space shuttle program may have ended, but data the space craft collected over the past three decades are still helping advance science. Researchers at the Jacobs School of Engineering at UC San Diego recently used measurements from NASA's Shuttle Radar Topography Mission to predict how changes in elevation, such as hills and valleys, and the shadows they create, impact power output in California's solar grid.

Current large-scale models used to calculate solar power output do not take elevation into account. The California Public Utilities Commission asked Jan Kleissl, a professor of environmental engineering at the Jacobs School of Engineering at UC San Diego, and postdoctoral researcher Juan Luis Bosch, from the department of mechanical and aerospace engineering, to build a model that does.

This is the first time this kind of model will be made available publicly on such a large scale, including all of Southern California, as well as the San Francisco Bay Area. It took the Triton Supercomputer at the San Diego Supercomputer Center here at UCSD 60,000 processor hours to run calculations for the model. Utility companies and homeowners can use the model to get a more realistic picture of the solar power output they can typically expect to produce. This is an especially important tool for utilities, because it gives them a better idea of how much revenue they can actually generate, Kleissl said.

Changes in elevation can have a significant impact on solar power output. The longer it takes for the sun to rise above the local horizon in the morning and the earlier it sets in the evening, the more solar fuel is lost. Solar days are longest on top of tall mountains. They are shortest in steep valleys oriented north-south, where it can take more than an hour longer for the sun to appear in the east.

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