-- This project is inactive --

US Solar Holdings, under the Thermal Storage FOA, is aiming to demonstrate commercial, utility-scale thermal energy storage technologies and provide a path to cost-effective energy storage for CSP plants >50 MW.


The project's key objectives include:

  • Further proof and cost reduction for thermocline technology
  • Development of the novel two-silo sand storage ("SandShifter") technology
  • Optimization of capital costs and full life-cycle costs through design approach, materials selection, and construction techniques
  • Development of system operation strategies
  • Maximization of overall utility value (particularly in terms of capacity maximization and time of energy delivery)
  • Analysis and optimization of operation and maintenance issues

US Solar Holdings is developing a method for storing thermal energy in sand by passing it over the surface of a heat exchanger.


For the thermocline portion, US Solar Holdings is creating a reference facility to support financing and operation of thermoclines at future, larger CSP plants. For the SandShifter, the project is focusing on identification and vetting of key issues for this novel thermal energy storage (TES) concept, with a goal of moving through these issues into an operational facility. Expected outcomes include:

  • Construction and operation of a 1-MW demonstration project
  • Cost-estimation and analysis showing cost-effectiveness (or not) at the 50+ MW scale.

By the end of the project they hope to show that these novel concepts for TES have the potential to reduce the cost of TES to <$15/kWth and achieve round-trip efficiencies >93%.

Publications, Patents, and Awards

Learn about other concentrating solar power research.