ALBUQUERQUE, N.M. — Researchers at Sandia National Laboratories are
working to lower the cost of solar energy systems and
improve efficiencies in a big way, thanks to a system of small
particles. This month, engineers lifted Sandia’s continuously recirculating falling particle receiver to the top of the tower at the National Solar Thermal Test Facility, marking
the start of first-of-its-kind testing that will continue through 2015.
The Sandia-developed falling particle receiver works by dropping
sand-like ceramic particles through a beam of concentrated sunlight,
capturing and storing the heated particles in an insulated tank. The
technology can capture and store heat at high temperatures without
breaking down, unlike conventional molten salt systems.
Conventional central receiver technologies
are limited to temperatures close to 600 degrees Celsius (1112 degrees
Fahrenheit), while operating temperatures for the falling particle
receiver could exceed 1,000 degrees Celsius. Higher temperatures mean
more available energy and cheaper storage costs because less material is
needed to transfer heat.
Sandia engineer Cliff Ho, the project’s principal investigator, said
the goal of the testing is to develop a prototype, cost-competitive
falling particle receiver that demonstrates the potential for thermal
efficiency greater than 90 percent, while achieving particle
temperatures of at least 700 degrees Celsius.
“This technology will enable higher temperatures and higher
efficiency power cycles that will bring down the cost of electricity
produced from concentrating solar power,” Ho said. “In addition, the
ability to cheaply and efficiently store thermal energy directly in the
heated particles will enable power production at night and on cloudy
days.”
Falling particle receiver technology is expected to further advance the state-of-the art in concentrating solar power tower systems capable of generating up to 100 megawatts of electricity. Sandia’s partners in the Department of Energy project are the Georgia
Institute of Technology, Bucknell University, King Saud University in
Saudi Arabia and the German Aerospace Center. The project is funded by
the U.S. Department of Energy’s SunShot Initiative, which aims to reduce solar energy costs and expand the use of solar energy technologies throughout the United States.
Sandia design engineer Josh Christian said the on-sun testing at the
solar tower will occur in two phases. First, researchers will test an
insert designed by Georgia Tech that slows falling particles inside the
receiver like a Pachinko board to increase the temperatures of the
particles as they fall through.
Sandia engineer Joshua Christian helped design the falling
particle receiver system, which converts the sun’s energy to electricity
for large-scale, concentrating solar power plants. (Video courtesy of Sandia National Laboratories) Click to view video.
Later this summer, Sandia engineers will remove the Georgia Tech
insert from the receiver and evaluate free-falling curtain
configurations. Weather and other factors will affect the pace of the testing.“New Mexico is great for this project because our state has pretty
consistent solar insolation throughout the year,” Christian explained.
“However the biggest thing we need to know is how much power is going
into the falling particle receiver. So a cloudy or hazy day is a big
challenge for us. An ideal day for testing is a clear day with no clouds
and no wind.” The tower at Sandia’s National Solar Thermal Test Facility stands 200 feet tall and is the only testing facility of its kind in the United States.
http://www.renewableenergyworld.com/articles/2015/07/testing-heats-up-at-sandias-solar-tower.html