Bright Source Energy

Solar Concentrator Molten Salt System


A molten salt system1 is a means to store thermal energy, thus mitigating the problem of an intermittent source for generating electricity at night or during cloudy weather. It is one of Tom Konrad2’s top ten favorites for an alternative energy future because it’s cheaper to store heat than it is to store electricity and concentrating solar power can produce a ton of heat without pollution or fuel.

Renewable Energy Access reports that the technical team that “developed the solar trough technology used in nine solar thermal plants built in Southern California between 1984 and 1990″ is back at it, again.

BrightSource Energy, Inc., a utility scale solar thermal company, announced last week that it has filed an Application For Construction (AFC) with the California Energy Commission (CEC) for development of a 400 megawatt (MW) solar power plant site. This is the first AFC to be filed in California since 1989 for the construction of solar thermal power plants.

BrightSource plans to build three separate solar plants on a site in California known as Ivanpah, about five miles southwest of Primm, Nevada. The site is located on federally owned land administered by the Bureau of Land Management (BLM).

BrightSource has applied to the BLM for a right-of-way grant to use the land for its solar power complex, which will consist of two 100 MW solar power plants and one 200 MW solar power plant. The plants will utilize Distributed Power Tower (DPT) solar field technology developed by Luz II, a wholly owned subsidiary of BrightSource Energy.

“BrightSource is in negotiations with California utilities for the purchase of the electricity that these solar power plants will generate,” noted John Woolard, CEO of BrightSource Energy.

The BrightSource technical team previously developed the solar trough technology used in nine solar thermal plants built in Southern California between 1984 and 1990. The company’s Luz Distributed Power Tower technology consists of mirrors called heliostats, which reflect the sun’s light to a central tower to heat water and run a steam turbine to create electricity.

Given how much solar thermal electric power has been in the renewable energy news, to include Federal encouragement, it may be worth noting that prospects can change when the incentive is removed and the project is unprofitable. RE commentator Jim Berry opines:

Oh God, this technology is back again. I remember one of these going bankrupt in the mid 90s. It used a molten salt core that remained liquefied by the solar. It never made a dollar for the investors, just the lawyers, banks, and management team, that held on to control and got an equity stake in the new corporation, which later went bust.

Sun Edison Solar Thermal Tower


Credit: Joe Flores, Southern California Edison

Large tracking mirrors or heliostats move to keep sunlight focussed onto a tower-mounted central receiver filled with a working fluid. The heated fluid produces steam that drives a turbine to produce electricity. The Sun Edison facility shown above also makes use of a thermal storage system and has gas fired boilers for backup to ensure that enthalpy is maintained. Even though the mirrors can be comprised of low cost material, such a field of heliostats accounts for 50-60 percent of the cost of this type of solar thermal power plant.

To which Steven Beckendorf responds:

I think you are confused about the solar technology that Bright Source is planning to use. The bankruptcy you refer to was Luz I, the company that built 9 parabolic trough plants in the Mojave during the 1980s. It failed when energy prices plunged in the early 1990s and government incentives for renewable energy development were withdrawn.

Bright Source and its subsidiary Luz II, while featuring many of the same people, has a new technology, a smaller version of the power tower technology that was also developed in the Mojave in the 1990s (Solar One) but was not commercialized in the US. Solar One was, at least partly, a victim of reduced research funding by DOE. The design has been successfully implemented in Spain, drawing on the lessons learned by Solar One in the US.

The Bright Source mini-tower version uses smaller mirrors that are easier to manufacture, transport and set up and thus should reduce the initial cost. It’s future is expected to be Bright, to coin a phrase.

Continue reading here: Sun Technics

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