US Researchers Pursue 5¢/kWh Energy Cost Goal with New CSP System

The US National Renewable Energy Laboratory (NREL) and the Department of Energy (DoE) are working on a state-of-the-art concentrated solar power (CSP) facility as the government looks to reduce the energy cost to a mere 5 cents per kWh.

The new technology is expected to have the potential to lower the cost of renewable energy and ensure that dispatchable energy is available – that too any time of the day.

For this the Department of Energy has given $2 million to NREL to develop a prototype or a model of a system that can harness energy potentials of molten salts. The process has to incorporate the elimination of the corrosive properties of the molten salts.

The CSP and the Molten Salts

Concentrated solar power is basically a constellation of a large array of mirrors (heliostats at times) that directs sunlight into towers that are especially erected to store the directed solar energy in the form of heat in sand, rocks and molten salt. This is actually a long lasting thermal heat storage. This means that this stored energy can be dispatched at any time of the day to fulfil the human energy demands.

The Department of Energy says that far flung areas that usually rely on traditional solar PV during peak hours can benefit from it. The agency has identified three imminent areas of innovation for novel concentrated solar power to be successful. The heat is stored in liquids like molten salts. The government has this time released funds for the first time outside ‘particle based storage’ research and development and NREL is directed to run a two-year liquid molten salt based program.

The key benefit of working with molten salts is that they can easily move through pipes and heat exchangers. The molten salts have an inherent challenge they corrode and damage the holding tanks during the process of transferring heat energy. But, the NREL says that it has largely solved this problem by making it relatively noncorrosive while controlling the chemistry and this has already been demonstrated in the lab.

The NREL has decided to use chloride salts to harness molten salts. The industry usually employs nitrate salts in most applications, the company says that nitrate salts maintain a greater level of stability under extreme temperatures.

NREL now has $2 million to build a prototype tank that utilizes extra insulation to keep the molten salts. These salts freeze at 400°C which is a very high temperature. Other things might also help the two agencies to get to the government target of producing CSP based energy at a price of 5 cents per kWh. First, the cost of CSP has fallen by 47 percent between 2010 and 2019. This will continue to dive.

“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,” says Kerry Rippy, who deals in inorganic chemistry at NREL.