0710ctt falling particle receiver lo res

[Image above] Technologists John Kelton and Daniel Ray perform inspection of the Falling Particle Receiver during a cloud delay atop the National Solar Thermal Test Facility at Sandia National Laboratories. Credit: Randy Montoya

About a year ago, I reported on a project at Sandia National Lab that was developing a novel solar energy storage technique that used ceramic particles. The lab was, at that time, just beginning to test its falling particle receivers, using the intense heat of concentrated sunlight to heat sand-like ceramic particles that cascade through the system.

Although similar energy collection and storage systems that use molten salt already exist, ceramics offer greater energy storage capability at a cheaper cost—really important parameters when it comes to solar technologies, which need efficient and viable solutions to offer up stored energy on demand for times when the sun isn’t shining.

In the year since I last wrote about Sandia’s falling ceramic particle receivers, the national lab has completed testing within its 3.5-year project to develop the technology.

And the results?

I’m going to go with “success” on this one.

According to a recent press release, “Sandia constructed and successfully demonstrated the world’s first continuously recirculating high-temperature 1 MWt falling particle receiver, achieving peak particle temperatures over 900°C and bulk temperatures over 800°C.”

The release continues, “The particle heating rate reached 100–300°C per meter of illuminated drop distance at concentrated solar irradiances of ~1,000 kW/m2 and thermal conversion efficiencies of ~80%.”

Compared to efficiencies of more conventional solar cell technologies, which hover right around the 20% mark, Sandia’s falling particle receiver offers up big potential for more widespread and economical use of solar energy.

However, these massive systems cannot be installed just anywhere—collecting concentrated sunlight requires a lot of mirrors to reflect that sunlight onto a central location. And with the recent fire at the Ivanpah concentrated solar facility in California, the safety of concentrated solar facilities has definitely been called into question.

Nonetheless, solar energy is a renewable resource that still offers some of the best potential to harness for our energy needs here on earth. Novel technologies will undoubtedly continue to evolve to better collect and store this invaluable resource for our continually demanding energy needs.

In the case of falling particle receivers, the project at Sandia continues forward. The national lab has been awarded additional SunShot Initiative funding, which extends through 2018, to develop a particle/supercritical carbon dioxide heat exchanger for the technology, according to the release.