Mark Mehos explains Concentrating Solar Power technology

Mehos believes this technology – known as CSP – is particularly promising because it can store up energy to be used on cloudy days.

Mark Mehos: Concentrating Solar Power, or what we call CSP, is a technology that takes the energy from the sun, converts that energy to thermal energy or high temperatures, and takes those high temperatures to run a typical turbine, to generate power.

Mark Mehos manages the Concentrating Solar Power Program at National Renewable Energy Laboratory in Golden, Colorado. Mehos is describing a type of solar power plant that can power thousands of homes.

Mark Mehos: The thing about CSP, is that they use concentrating optics, typically mirrors or sometimes lenses, to concentrate sunlight.

Large arrays of mirrors or lenses, he said, can be located in sun-saturated regions such as Spain, and the American Southwest. The sunlight they collect is converted to electricity through a turbine, or it can be saved in a thermal storage system.

Mark Mehos: The advantage there – and it is a significant advantage – is that if the day is cloudy, but you still want to generate electricity, you can draw from that thermal storage system and still generate electricity.

Mehos said this system can store up to six hours of solar energy. Within the storage tanks are millions of gallons of molten salt. The salt can reach up to 400 degrees Celsius, or 750 Fahrenheit as it retains the sun’s heat, to be transferred later into electricity. Mehos said scientists are still working to make this kind of solar power cheaper, and more efficient.

Mehos explained that there are three main types of Concentrated Solar Power: the parabolic trough, the solar power tower, and the parabolic dish. EarthSky asked why there is a need for so many different variations on solar power.

Mark Mehos: The reason for that is the infancy of the technologies right now. What we have is a number of different technologies that are being tried. Different companies feel a particular technology may be the technology that will win. It’s possible that one may win. It’s possible that all of the technologies might win. They’re just different approaches to generating electricity from sunlight.

Some of these plants – such as the parabolic trough – have been operating for twenty years. But the technology continues to develop. Spain has been a leader in pioneering new Concentrating Solar Power plants, and America is following.

Mark Mehos: Spain is a good example of where a lot of plants are being built. Those plants are all on the order of 50 megawatts. In the U.S. we are starting to see much, much larger installations being proposed. There are companies now proposing installations of 280 megawatts, for example.

Mehos said 100 megawatts powers 30,000 homes, on average. He said a choice of these solar technologies is available to utilities now.

Mark Mehos: So it is an option, but it is a higher cost than conventional technology with the current incentives. So what’s needed is to continue the research and development that we are doing, continue and enhance policies, to try to increase manufacturing base. Make lands available. It takes a combination of research and policy for this to happen.

Lindsay Patterson