BrightSource Energy announced this week that they could chop down the size of their giant 750 MW project in California by 200 MW and yet still make the same 4,000 gigawatt-hours a year of power they are contractually required to produce for California, by adding their proprietary SolarPlus night time storage.
The seven-plant power tower project is under a power purchase contract with Southern California Edison which supplies electricity to customers in Southern California. But BrightSource spokesman Keely Wachs told Todd Woody on Monday that by adding storage for use for several hours at a time that only six of the seven planned solar “power tower” stations will need to be built, saving some 1,280 acres of desert land.
Since land-use has become a contentious issue with some California conservationists, this should be a win-win.
If approved by state regulators, the amended contracts with Southern California Edison will also result in lower costs for utility customers.
The change trades on the competitive advantage of solar thermal, that it can include night time storage, which solar PV cannot.
Unlike traditional solar PV, which makes electricity directly, the various kinds of solar thermal all create heat by reflecting sunlight using mirrors, making steam to drive turbines which then generate power, just like any other thermal power such as gas, coal or nuclear. There are many designs, and improvements are constantly being made as the technology moves to utility-scale.
The storage option is important because as the price of PV keeps dropping, it becomes harder for the other kinds of solar to compete, and some anger has been revved up by the media because utilities signed up for previously cheaper solar thermal contracts that have now become comparatively more expensive with the new lower solar PV rates.
Even just a year or so ago, when PV was expensive, and most of these solar contracts were signed, solar thermal, using mirrors, was the cheaper option.
Making polysilicon for PV out of sand sounds cheap and easy, but it is an extremely finicky process, and so making PV was intitially an expensive, almost artisanal procedure. But, as more factories have been automated for its mass production in China, solar PV prices have now bottomed out.
But on the other hand, solar thermal electricity can store part of the heat it makes, for use later,because it creates heat to make power. Heat can be very efficiently stored in salt solutions (keeping almost 100% of the heat) and tapped later on demand.
For Southern California Edison, BrightSource now suggests it add a newly developed proprietary technology that can store solar heat so it can be released to create steam after dark or when electricity demand spikes, making it a more reliable electricity source than PV.
If the California regulators agree to the updated project including salt storage, this could develop into the standard for solar thermal, and solve a problem of solar intermittency. This breakthrough would be yet another way that the originally Israeli company is creating a first for world solar. BrightSource’ parent company, Luz, proved the efficacy of solar themal in the California desert for several decades – as the world’s only solar project.