More than 300,000 individually computer-controlled mirrors. Three 459 foot tall towers topped with solar boilers at 1,000 degrees Fahrenheit. 392 megawatts of Power. The Ivanpah Solar Electric Generating System has gone live, a huge solar power plant built by BrightSource with backing from Google, NRG, and others, set to provide clean energy to 140,000 homes. For all its advanced technology, though, Ivanpah may be more important as a gateway to even more advanced solar energy projects.
Fields upon fields of photovoltaic panels aren't new, but Ivanpah takes a new approach to harnessing the sun's energy. Rather than each mirror converting sunlight directly to electricity, they're carefully angled to direct its rays at the sunlight boilers atop each tower.
Those towers, black-coated to absorb more solar energy, each contain water. That's warmed until it reaches the stage of superheated steam, and then that steam is piped down to spin turbines which create electricity. In fact, the turbine technology is just as might be found in a traditional gas or coal power station.
Unlike coal or gas, there are no vast swathes of CO2 being emitted; unlike traditional photovoltaic power installations, the ground beneath each computer-directed mirror needn't be flattened or cleared of vegetation, and Ivanpah's systems can take into account changes in the land's contours.
For all its advanced technology, however, Ivanpah is already arguably outdated. BrightSource is already looking beyond the existing boilers to using salt storage instead, as part of its SolarPLUS system.
Rather than directly heating the water, SolarPLUS heats up a molten salt mix of sodium nitrate and potassium nitrate. That works as a "heat battery" which can then be tapped later on to generate steam and run the turbine.
The advantage is more control over the times when electricity is produced. BrightSource says its SolarPLUS system can store as much as six hours' worth of heat power for later release, meaning that even when the sun isn't shining the plant can still generate electricity; useful given it's often during the evening when surges in demand arrive.
You can take a virtual tour of the whole Ivanpah facility to find out more.