High in the stark Nevada desert, a couple of hundred miles north-west of Las Vegas, is the shimmering circular mirage of Crescent Dunes. Ten thousand silvery glass panes surround a tall central tower, which stands like a twinkling needle in the featureless landscape around it.
Solar Power…at Night?
Every hour the sun beams onto Earth more than enough energy to satisfy global energy needs for an entire year. Since its discovery, harnessing solar energy efficiently has been the subject of researches for many years. But one thing about solar energy collection is that it’s only available during the day—until now.
Composed of a tall central tower surrounded by a total of 10,437 glass panels, with more than one million square meters (~10.8 million square feet) of glass, this solar oasis is capable of storing energy, enough to supply electricity to 75000 households during peak demand periods, 24/7.
Molten-Salt Storage’s Huge Potential
The central tower then secretes a reservoir of potassium and sodium nitrate—about 25,000 metric tonnes (~28,000 US tons) of it—heated in advance to 288°C (550°F), at which temperature the mixture is a clear, water-like liquid.
This is then circulated in narrow, thin-walled tubes, rising dramatically in temperature when exposed to the fearsome, concentrated sunlight at the top of the tower. “We heat it to 560°C (1040°F),” says Smith, “it flows back down the tower and we capture it in a large tank.”
The molten salt efficiently maintains the heat and when the energy is required, it is converted to electricity through a conventional steam turbine.
Highlighting Crescent Dunes’ zero pollutant-emissions and more efficient water consumption than coal or nuclear power plants, Smith believes that their tech is not just a substitute for photovoltaic panels. He believes that it could also be a potential competitor to conventional fuels in the future.
“It’s really an alternative to fossil fuel or even nuclear. You couldn’t power a city with just PV and wind, but you could with CSP, because of the storage capacity.”