Israeli firm looks to keep solar power generators running at night

NEGEV DESERT - Reuters

An Israeli firm says it has developed a more efficient and cheaper solar power system that can enable thermal power plants to run during both days and nights. AP Photo

An Israeli solar power company, Brenmiller Energy, says it has developed a new, more efficient way to store heat from the sun that could give a boost to the thermal solar power industry by enabling plants to run at full capacity night and day.

By next year company founder Avi Brenmiller said he will have a 1.5 megawatt (MW), 15-acre (6-hectare) site in the Negev desert connected to Israel’s national grid, and a number of 10 to 20-MW pilots abroad are expected to follow, which will produce electricity at a price which competes with power from fossil-fuelled plants.

“A couple of years from now, not later than that, we will be putting full-size commercial plants to work. Because the basic technology we use here is a bankable technology ... I’m sure that banks will not hesitate to finance such projects,” he said.

Many have tried to find ways to keep solar thermal power generators running after dark, but current solutions have shortcomings and have not always proven cost-effective.

The direct generation of electricity by photovoltaic (PV) solar panels is a far more common way to convert solar energy than by using solar heat to fuel thermal power plants, which take up more space and are not suitable for small-scale applications such as residential homes.

But a row of parabolic mirrors now tracks the sun at Brenmiller’s research site in the searing Negev desert, concentrating the rays to generate the steam needed to drive a turbine for producing electricity.

It is a technique that has been used for years but in addition to immediately generating steam some of the solar heat is also conducted by a fluid into a novel storage system buried beneath the mirrors which operates at 550 degrees Celsius.

This store can then be tapped at night or on cloudy days to keep the steam supply to the turbines flowing night and day, said Avi Brenmiller, chief executive of Brenmiller Energy.

Competitive price

The innovation is in the cement-like medium that stores the heat, a technology that Brenmiller says is more efficient than other systems on the market, such as those using molten salt, which has severe price and operational drawbacks.

“We will have this technology at conventional fuel prices with the same availability around the clock. I think that’s the major breakthrough here,” he said from the control room of the project, which he called a working proof of concept.

Brenmiller was a co-founder and chief executive of Solel Solar, a producer of concentrated solar power fields which was bought by Siemens in 2009 for $418 million but subsequently closed by the German group last year. He has already poured $20 million of his own money into the latest venture over the past two years.

An hour of sun produces enough energy to sustain three hours of equivalent electricity generation, Brenmiller said, and with every 24 hours of storage, 5 percent of the heat is lost.