Sandia, with partners Georgia Tech, Bucknell University, King Saud University, and DLR (the Institute of Solar Research of the German Aerospace Center), was awarded funding to develop a concentrating solar power falling-particle receiver and heat-exchanger system under the DOE SunShot Initiative.
Conventional central receiver technologies are limited to temperatures of ~600 °C with power-cycle efficiencies ~40%. At higher temperatures, nitrate salt fluids become chemically unstable. In contrast, direct-absorption receivers using solid particles can increase the heat-transfer media’s maximum temperature to >1,000 °C, also increasing power-cycle efficiencies (>50%).
Thermal energy storage costs can be significantly reduced by storing heat at higher temperatures in an inexpensive medium (i.e., sand-like particles)—lowering the levelized cost of energy toward the SunShot goal of $0.06/kWh.
Once heated, the particles may be stored in an insulated tank and/or used immediately to heat the power cycle’s working fluid (e.g., steam, supercritical CO2, air). The falling-particle receiver appears well-suited for 10–100 MWe power-tower systems.
The research team is pursuing technical innovations in
- receiver design, with consideration of particle recirculation, air recirculation, and novel particle-heating designs;
- particle materials to increase solar absorptance and durability; and
- balance of plant for falling-particle receivers (thermal storage, heat exchange, particle conveyance).