Energy storage is becoming a vogue technology for concentrating solar thermal project developers, particularly as they face intense pressure to reduce costs. BrightSource Energy said Wednesday it, too, will offer an energy storage option made from molten salt for its power plant design.
BrightSource will use the molten salt to store electricity produced by its concentrating solar thermal power plants, which use flat mirrors to concentrate and direct the sunlight to heat up water in a tank atop a tower (see image). The process generates steam, which is then sent to a turbine to produce electricity.
In a design with storage, the steam will be used to heat the molten salt, which is particularly good at trapping heat. Power plant operators can use the hot molten salt to produce steam and then electricity whenever it’s needed.
Energy storage makes it possible for developers to say their solar thermal power plants can provide electricity around the clock, much like what coal- and natural gas-fired plants can do now. The ability to produce power at any time of day is a big advantage that fossil fuel power plants have that solar and wind power largely don’t have today. However, some solar power plants in Spain already are operating with storage attached.
Utilities in the country are facing increasing mandates to add more renewable electricity to their energy mix, so their interest in energy storage has grown tremendously in recent years. Although the interest is there, utilities are quite cautious about investing in energy storage, partly because the more promising technologies, such as lithium-ion batteries, haven’t been proven to be economical at scale.
The Electric Power Research Institute pegs 2012 as a turning point for electric grid energy storage technology development because by then, companies that have collectively received more than $250 million in federal stimulus funding are expected to complete research and development work and move into field trial stages.
Adding energy storage hasn’t always made financial sense. In fact, a BrightSource executive expressed that sentiment in 2009. Now, solar thermal project developers often say adding storage will both increase the hours and lower the cost of electricity generation from their plants.
Storage as a way to compete with photovoltaics
The truth is that adding energy storage has become one way for solar thermal power developers to compete with the competing tech solar photovoltaics (PV) that uses solar panels to generate electricity. Solar panel prices have plummeted more than half over the past two years, and PV power projects don’t need the large land and amount of water that solar thermal power plants require.
The combo of lower panel prices, among other trends, has prompted some solar thermal players to jump into the PV power plant development business. For example, Solar Trust of America is doing that, and so is SolarReserve. In addition, some PV project developers, such as Solon, also are looking at adding storage.
Beyond BrightSource, solar thermal project developers already are incorporating molten salt storage into their projects. Abengoa Solar and SolarReserve have added storage to their projects that are getting federal government loans. Abengoa, which has gotten a $1.45 billion loan, plans to add storage to its 250 MW Solana project in Arizona. SolarReserve is working on closing a $737 million loan for its 110 MW Crescent Dunes project in Nevada that also will include storage.
The company announced plans to go public in April this year. The initial public offering will provide some of the capital for BrightSource to complete other projects that it’s developing to sell power to California utilities.
Images courtesy of BrightSource Energy