Here comes the sun: Tethered-balloon tests ensure safety of new solar-power technology

April 22, 2021 8:19 am Published by

What do tiny dust particles, 22-foot-wide red balloons and “concentrated” sunlight have in common?

Two small balloons against a blue sky to the left of a large tower with a solar power receiver attached at the top.
A team of researchers from Sandia National Laboratories recently used tethered balloons to collect samples of airborne dust particles to ensure the safety of a falling-particle receiver for concentrating solar power, an emerging solar power technology. (Photo by Randy Montoya)

Researchers from Sandia National Laboratories recently used 22-foot-wide tethered balloons to collect samples of airborne dust particles to ensure the safety of an emerging solar-power technology. The study determined that the dust created by the new technology is far below hazardous levels, said Cliff Ho, the lead researcher on the project. Ho’s team just received $25 million from the Department of Energy to build a pilot plant that will incorporate this technology.

This next-generation renewable energy technology is called a high-temperature, falling-particle receiver for concentrating solar power. Concentrating solar power, while not as common as solar panels or wind turbines, has several advantages over those renewable energy sources, including the ability to store energy in the form of heat before converting it into electricity for the power grid.

One concentrating solar power plant in Arizona uses molten salt to store this heat for six hours, while other plants, in theory, could store heat for days or weeks, said Ho, Sandia’s concentrating solar power expert. This would help power companies even out the daily and seasonal variation of power produced by solar panels and wind turbines.

The falling-particle receiver works by dropping dark, sand-like ceramic particles through a beam of concentrated sunlight, then storing the heated particles. These round particles cost about $1 for 2.2 pounds and can get a lot hotter than conventional molten-salt-based concentrating solar power systems, which increases efficiency and drives down cost. The Sandia team also evaluated other particles like sand, which costs only a few cents per pound, but they determined that due to the ceramic particles’ ability to absorb more solar energy and provide smoother flow, ceramic particles were the best way to go. The Department of Energy’s goal is to get the cost of electricity from concentrating solar power down to five cents per kilowatt hour, comparable to conventional fossil-fuel-based power.

However, the re-used particles can eventually break down into fine dust. The Environmental Protection Agency and the Occupational Safety and Health Administration regulates tiny dust particles, finer than talcum powder, that are known to pose a risk for lung damage.

“The motivation for doing the particle sampling was to make sure that this new technology for renewable energy wasn’t creating any environmental- or worker-safety issues,” Ho said. “There are particles being emitted from the falling-particle receiver, but the amounts are well below the standards set by the EPA and National Institute for Occupational Safety and Health.”

Read the complete news release for more about how the research team is using tethered balloons to catch dust and ensure safety of new solar-power technology.

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