Solar-thermal power supporters often cite energy storage as a benefit the technology brings. But it may not be practical for commercial deployment. At least not now. 

Charles Ricker, senior vice president of marketing and business development at BrightSource Energy, said the company isn’t adding the energy storage component its projects because it doesn’t make financial sense.

“We have the ability to add storage, but we are not doing that in any of the projects we are doing,??? said Ricker during a panel at the UC Berkeley Energy Symposium Monday. “The return on investment isn’t there.??? The Oakland, Calif.-based companies have deals to supply solar power to PG&E and Southern California Edison. 

Increasing the size of the solar-thermal power plant is a better way to design a profitable project, Ricker said.

Solar-thermal power plants are meant to be large-scale projects that, partly because of their sizes, can cost lower to build and operate than projects using other types of solar technologies. Unlike a power plant using solar panels, a solar-thermal power plant requires a lot more land for the array of mirrors to concentrate the sunlight for generating steam, which is then fed to a generator to produce electricity.

During that process, the heat used for steam generation can be stored in a tank containing materials such as molten salt, which remains a liquid when heated above 430-degree Fahrenheit. The salt can be pumped to generate steam at night to run the generator. This process can keep a solar-thermal power plant operating when the sun isn’t shining, a feature that sets this type of solar power plant design apart from solar panel-based systems (attaching batteries is too expensive).

But adding the storage component doesn’t make financial sense at this time, Ricker said, because the most lucrative way to make money from solar is to supply the power when utilities need it the most. That would be in the early afternoon when it’s hot and the air conditioning is on full blast. Power producers can sell electricity at a premium during peak hours. 

“A lot of companies are talking about solar as a baseload plant,??? said Ricker, referring to the idea that a power plant can meet the continuous energy demand of the market it serves. “We don’t see that.???