California took a leap forward in its pledge to get 33% of its power from renewables by 2020 with the opening of the Ivanpah Solar Electric Generating System last week. While not the first solar thermal plant, Ivanpah is the biggest. The five square-mile, 392 megawatt facility can power more than 140,000 homes in California, and it’s now ready to perform at full strength.
When we talk about solar, it’s usually photovoltaics, which convert energy from the sun into usable electricity. Solar thermal is a competing technology that has seen a recent rise in popularity across the Southwest for larger-scale electricity production. Instead of directly converting solar radiation into grid-ready electricity, solar thermal plants function like coal plants, using a heat source to produce steam to drive a turbine, powering a generator to make electricity. Ivanpah uses 170,000 mirrors, synced to the movement of the sun with a unique algorithm, to focus hot beams of light onto three energy towers.
Burning coal releases greenhouse gases, mercury and other pollutants into the atmosphere. Turning to solar thermal plants like Ivanpah cuts down on those emissions, but they carry problems of their own. Environmentalists protested the building of the Ivanpah facility because it’s located in the Mojave’s threatened desert tortoise habitat. The powerful, concentrated beams can also burn or kill birds that fly through the facility.
Ivanpah was expensive to build. The $2.2 billion facility is more in line with a 650 megawatt or greater coal plant. The facility also lacks the molten salt storage technology that other solar thermal plants use to keep producing power after the sun goes down. While it’s not a miracle solution to our energy demand, the technology is proven and could be just one of a number of clean energy sources to displace fossil fuels.