As 2013 begins, the concentrated solar power (CSP) industry in the U.S. is on the brink of a major turning point. After years of hesitancy to invest in CSP due to required increases in efficiency and cost reductions, a wide market acceptance of solar thermal power plants is knocking at the door, driven by the development of next generation technologies in thermal storage, heat transfer and plant components. These developments, along with the current U.S. political and solar power market, will drive lower costs and make utility-scale CSP commercially viable for the first time.
First, let’s look at recent developments in solar thermal storage and heat transfer. Significant technological breakthroughs have been made in molten salts, the technology that allows utility-scale CSP plants to generate baseload power and differentiates CSP from other renewable power sources. Next generation ternary molten salts using potassium calcium nitrate (CN-K) have an expanded temperature range, enhanced storage ability and improved safety over current salts and thermal oils. The lower melting point means the salts require less energy to reach their effective range, providing improved heat transfer and storage performance for plant operators. The lower melting also reduces the risk of damage or accidents from salts freezing in circuits, a serious issue for the continuous operation of a plant.
There have also been significant improvements to components of CSP plants such as receivers and collectors due to new coatings and improved design. New coatings being used on vacuum-insulated receivers, which convert the rays of sun into heat, are now able to operate with a 95.5 percent degree of absorption. Further improvements to the design of receivers have expanded the active surface to 96.7 percent of the length, which also increases absorption capacity. Research continues to create new reflective films, reflector panels and adaptive optics for solar collectors, in order to increase the performance of solar collectors over existing designs as well.
More importantly, these same technologies have also decreased the capital and operating expenditures for utility-scale CSP projects, making them more profitable for investors and plant owners. To start, the price of new ternary molten salts is more competitive than current binary salts, a trend that will likely increase over the coming years. Additional cost savings are due to the salts’ lower temperature range, which means less salts need to be purchased overall and these are less expensive to heat during the melting process. In addition, purer and less-corrosive synthetic molecules have been developed which help reduce corrosion of plant components, as well as related maintenance costs and safety issues.
Improvements and efficiencies are also being made in other areas of CSP plant technology, including mirrors, receivers and tubes. For instance, the National Renewable Energy Laboratory (NREL) has developed less expensive CSP collectors by replacing glass-based models with a silver polymer sheet that has the same performance as the heavy glass mirrors, but at much lower cost and weight. Improving collector designs and using advanced optical materials that have lower cost and higher performance will continue to reduce the cost of collectors, which can comprise up to 40 percent of the total CSP system costs.
In addition to technological improvements, the U.S. solar industry can take advantage of favorable state and federal policies, which continue to drive developments and cost reductions in renewable energy technologies through a mix of tax incentives, government loans, loan-guarantees and grants. One notable example is the federal government’s SunShot CSP Research and Development program, which recently announced a $55 million investment in 21 projects at various companies, universities and federal agencies to address the technical barriers all four major CSP subsystems: solar fields, receivers, power plants and thermal storage. The program seeks to reduce the cost of CSP from a current price of $0.21/kWh to a goal of $0.06/kWh.
Factors other than government policies also make the U.S. perfectly positioned for the rapid development of competitive, clean and renewable utility-scale solar thermal power. First, the country’s geography provides natural advantages for developers. Some of the world’s best irradiation locations are located in the U.S. Southwest, where high-land availability also means plant managers can develop larger, more-efficient CSP plants which will lower costs and produce better yields. Additionally, the size of the U.S. economy, coupled with the size and depth of its financial markets, puts the country in position to dramatically ramp up utility-scale CSP capacity.
The time for utility-scale CSP has never been better. Technological breakthroughs in thermal storage, transfer and collection, coupled the current U.S. political and solar power market have the potential to provide affordable and reliable solar thermal power for generations to come. Now for the easy part: seizing this unique opportunity.
Lead image: CSP plant via Shutterstock