Harnessing the sun’s energy with tiny particles
Engineers at Sandia National Laboratories, along with partner institutions Georgia Institute of Technology, Bucknell Univ., King Saud Univ. and the German Aerospace Center (DLR), are using a falling particle receiver to more efficiently convert the sun’s energy to electricity in large-scale, concentrating solar power plants.
Falling particle receiver technology is attractive because it can cost-effectively capture and store heat at higher temperatures without breaking down, which is an issue for conventional molten salts. The falling particle receiver developed at Sandia drops sand-like ceramic particles through a beam of concentrated sunlight, and captures and stores the heated particles in an insulated container below. The technique enables operating temperatures of nearly 1,000 C. Such high temperatures translate into greater availability of energy and cheaper storage costs because at higher temperatures, less heat-transfer material is needed.
Central receiver systems use mirrors to concentrate sunlight on a target, typically a fluid, to generate heat, which powers a turbine and generator to produce electricity. Currently, such systems offer about 40% thermal-to-electric efficiency. The falling particle receiver enables higher temperatures and can work with higher-temperature power cycles that can achieve efficiencies of 50% or more.
“Our goal is to develop a prototype falling particle receiver to demonstrate the potential for greater than 90% thermal efficiency, achieve particle temperatures of at least 700 C, and be cost competitive,” said the project’s principal investigator, Sandia engineer Cliff Ho. “The combination of these factors would dramatically improve the system performance and lower the cost of energy storage for large-scale electricity production.”
The project is funded up to $4 million by the U.S. Dept. of Energy (DOE)’s SunShot Initiative, which aims to drive down solar energy production costs and pave the way to widespread use of concentrating solar power and photovoltaics.
Source: Sandia National Laboratories