Ken Silverstein | Aug 06, 2013

Solar prices are coming way down while the technologies to deliver the product are fast improving. But not all ideas are created equal. The question now is whether developers will focus on rooftop solar panels or whether they will renew their efforts in utility-scale solar power.

Concentrated solar power (CSP) focuses sunlight, usually with mirrors, to heat a fluid to high temperatures to drive the engine. That differs from the more traditional approach of photovoltaic solar power systems in which light interacts with sheets of semiconductors to generate electricity. That technology is more suitable for smaller projects.

Right now, about 520 megawatts of utility-scale solar is installed in the United States while much more rooftop solar are installed. According to the Solar Energy Industries Association, five mega projects are to hit the market by 2014. That would increase that total to1,300 megawatts. Meantime, there are 1,950 megawatts of CSP projects in power purchase agreements.

While concentrated solar power has a wider reach and greater dispatchability than photovoltaic solar power, it is still at least twice the cost of generation powered by fossil fuels. Prices, though, will come down. As more projects are built, the cost curve will fall. And, if such technological progress is combined with federal legislation that puts a price on carbon emissions, solar manufacturers and producers would crank up.

In any event, a key obstacle is that conventional fossil-fired facilities can operate all the time. Green energy plants are used as "peaking" facilities that run typically on the hottest days. "With intermittent renewables, we have to create the storage ourselves," says Michael Winkler, professor at the Schatz Energy Research Center at Humboldt State University, who talked earlier with this reporter.

But some smart people are working on that. AREVA Solar is collaborating with Sandia National Laboratories on a new CSP installation with thermal energy storage, allowing plant operators to provide solar power after sundown. It says that its plants will gather energy during daylight hours to generate power as needed.

Still Untested

To be sure, skeptics say that while the land space may exist to construct solar farms, the technology is still expensive and unreliable. CSPs can take years to build because they need thousands of large mirrors, steam generators and salt tanks. Constructing photovoltaic deals is a much simpler process.

The good news is that solar power, generally, used to cost $1 a kilowatt hour. Right now, such prices are between 12 cents and 30 cents for the same unit, although with federal subsidies they are nearly on par with competing forms of power generation. As new technologies are ushered in, the hope is that prices will fall to around 6 cents a kilowatt hour in the coming years.

The Concentrated Solar Power Alliance profiles three projects: Gemasolar, Brightsource and Solana. Gemasolar, it says, is 20-megawatts, which uses a molten salt storage tank that permits electrical generation for 15 hours without any solar feed. It is based in Spain, which is the globe’s leading location for CSP with 632 megawatts, says Wikipedia.

Brightsource is currently being deployed at the Ivanpah Solar Electric Generating System in California’s Mojave Desert -- a deal that got underway in 2010, says the association. It will deliver solar power for PG&E and Southern California Edison. It is the largest CSP plant to be constructed at 392 megawatts, it adds.

And, lastly, it points to the Solana Generating Station, which is a 280-megawatt plant near Phoenix to be completed this year. It will also be able store energy during non-sunlight hours to better meet Arizona residents’ peak demand, it says.

It is too soon to determine whether smaller-scale or larger-scale projects will be the wave of the future. While concentrated solar power is more efficient and can offer storage, it is still relatively expensive and untested. At the same time, such facilities require extremely large plots of land and, as is the case for all utility-scale projects, they are difficult to get permitted. Photovoltaic energy, by comparison, is proven, less controversial and can be easily connected to existing power lines.

The CSP technology is getting its chance to shine. If such utility-scale solar power can be dispatched from a central location to large urban areas, it would have the potential to change the energy paradigm both in this country and around the world.

 

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