U.S. Department of Energy - Energy Efficiency and Renewable Energy

SunShot Initiative

Dual-Purpose Heat Transfer Fluids for CSP

argonne logo Photo of three gray circular shapes that are overlapping.

A high-resolution TEM of the core/shell nano particle synthesized and dispersed in a high-temperature fluid for thermal energy storage. The outer shell encapsulates an inner phase-change material that melts during heating and releases the stored latent energy when the core freezes.

Argonne National Laboratory, under an ARRA CSP Award, is developing advanced heat transfer fluids (HTFs) by incorporating multifunctional engineered nanoparticles in heat transfer applications and thermal energy storage.


Current high-temperature energy storage fluids, such as molten salts or oils, are relatively limited in terms of their thermal energy storage capacity. By improving the conversion of solar (optical) energy to thermal energy, net energy stored in the fluid will be greatly enhanced. The development of high-efficiency and high-heat-capacity thermal storage fluids:

  • Reduces the overall thermal storage costs
  • Increases system efficiency
  • Reduces structural storage volume
  • Contributes to reaching overall Sunshot cost targets


Argonne is adding solid particles to HTFs to increase their heat capacity. If the solid particles happen to be phase change materials, then the specific heat and heat capacitance of the fluid will increase substantially. Regardless of whether or not the solid particles are a phase change material, adding them to an HTF has the potential to reduce the thermal resistances in the HTF loop because of the enhanced thermal properties.

Publications, Patents, and Awards

At this time, this project does not have published articles, patents, or awards.

SunShot logo

Quarterly Progress Reports

Learn about other DOE competitive awards for concentrating solar power research that are in progress.