A press statement has revealed that the National Renewable Energy Laboratory (NREL) and the Department of Energy (DoE) are both working on the next generation of CPS facilities as part of the DoE’s plans to reach an energy cost goal of 5 cents per kWh. In order to achieve this goal, a U.S. government agency awarded NREL $2 million to create a prototype for a system that can harness the great energy potential of molten salts while curbing their corrosive properties.
Concentrated Solar Power (CPS) makes use of a large array of mirrors, or heliostats to direct sunlight into collection towers that are used to store energy in the form of heat in the sand, rocks, or molten salt. As it can store long-lasting thermal energy, it can dispatch the energy as well at any time of the day. It is particularly useful in areas that might rely on traditional solar PV energy during peak hours.
Three key areas of innovation for CPS have been identified by the DoE. And these are: storing heat in liquids like molten salts, sand-like particles, and also in gases. The U.S. government agency has provided funding for NREL to run a two-year liquid molten salt research program.
Moreover, it is easy to work with molten salts as they can easily move through pipes and can exchange heat. But a few challenges are there. For example, the material is corrosive. It can cause damage to holding tanks during the process of transferring energy. However, according to Craig Turchi, who leads thermal energy science and technologies research at NREL, the researchers have “actually solved that problem by and large. NREL and partners did a lot of great science on salt chemistry — how to purify it, how to make it relatively noncorrosive if you control the chemistry, and we demonstrated that in the lab.”
In its bid to harness molten salts, NREL decided to utilize chloride salts as opposed to nitrate salts typically used in other molten salt applications. The DoE awarded NREL $2 million for the creation of a prototype tank that uses extra insulation to keep the molten salts, which freeze at 725 Degrees Fahrenheit. This, alongside the work NREL has carried out on the corrosion problem, means we might be a step closer to viable molten salt CPS.
Moreover, the cost of CPS has fallen by 47 percent between 2010 and 2019 due to some more innovations, and the price will only continue to fall. According to Kerry Rippy, NREL expert in inorganic chemistry, “there are multiple potential avenues for this research to be valuable. It can be beneficial for solar fuel synthesis; it could enable high-temperature fuel cells, and the nuclear industry is also really interested in this research.”
More about CSP can be accessed from here.