Argonne Mechanical Engineer Wenhua Yu installs a cylinder of high-conductivity foam into a prototype container as former postdoctoral fellow Taeil Kim, makes adjustments to a heat transfer loop in the background. Argonne researchers received funding from the U.S. Department of Energy SunShot Initiative to scale up and demonstrate their novel thermal energy storage system, which efficiently stores solar energy as heat for later use generating electricity. Total project funding is $1.6 million and includes an industry cost sharing arrangement.Photo courtesy of Argonne National LaboratoryOn September 16, 2015, the U.S. Department of Energy SunShot Initiative program announced funding awards to several research projects that aim to make concentrating solar power (CSP) plants cost competitive with traditional forms of electricity. Argonne National Laboratory and its industrial partners, Koppers Inc. and Parker Hannifin Corp., received a SunShot award to scale up and demonstrate Argonne’s novel thermal energy storage system, which efficiently stores solar energy as heat for later use as electricity on the electrical grid. Total project funding is $1.6 million and includes an industry cost sharing arrangement.

Current CSP plants use an array of mirrors or lenses to concentrate sunlight to heat a fluid that creates steam to then power electricity-producing turbines. Thermal storage systems are able to store solar energy so that the turbines can continue to run at night or on cloudy days when the sun isn’t shining. This dramatically improves plant capacity.

To maximize plant efficiency, however, it is essential that thermal storage systems operate at temperatures more than 200°C higher than current systems. For this purpose, high-temperature phase-change heat storage materials are being investigated that store heat as they melt, a property that is associated with the latent heat of the material. When the melted phase change material freezes, heat is released and can be recovered. Phase-change materials use much less material than current systems, lowering the cost of the thermal storage. Use of such materials, however, has been hindered by the fact that they conduct heat very poorly.

A team of researchers at Argonne has developed a composite heat storage material that receives and releases heat very rapidly. This material consists of high-conductivity foams that have been infiltrated with a high-temperature phase-changing material. The awarded scale-up and demonstration project will yield an energy storage system that has three times the capacity of the current lab-scale system.

In awarding a total of $32 million, the SunShot Initiative is funding transformative projects that promise to meet the targets set out in the SunShot Vision Study. One of the key findings of this study is that achieving the level of price reductions envisioned in the SunShot Initiative could result in solar energy meeting 14% of U.S. electricity needs by 2030 and 27% by 2050.