CSIRO Claims Falling Particle Concentrated Solar Power Can Lead To A Net Zero Economy

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A few days ago, we reported on a new plan by researchers at MIT that would create clean hydrogen from water using only sunlight. Not just ordinary sunlight, but the power of the sun focused on a single point by an array of mirrors, a technology known as concentrated solar power, or CSP.

It really is just a scaled-up version on that experiment you learned at summer camp where you used a magnifying glass to focus sunlight until it was hot enough to burn your initials onto a piece of wood. The difference between a CSP facility and a conventional solar farm is the captured heat can power conventional supercritical steam turbines for up to 15 hours, whereas the solar farm only produces electricity while the sun is shining.

Now Australia’s Commonwealth Scientific and Industrial Research Organization — popularly known as CSIRO — says its CSP research facility in Newcastle north of Sydney has announced a breakthrough in its investigation of “falling ceramic particles” technology that captures and stores solar energy as heat.

Dr. Jin-Soo Kim, who leads the solar technologies team, said this week the group has reached a critical milestone temperature of 803 °C (1477º F) for the first time at the falling particle receiver by using a new and novel concept. “This is significant because it creates the opportunity for greater renewable energy storage when combined with our patented heat exchanger,” Jin-Soo said. “This technology is key to delivering low cost renewable energy at scale for the decarbonization of Australia’s heavy industries. Over eight years of development and thousands of hours were invested to reach this outcome.”

The basic idea behind CSP dates back to the 1800s when European inventors tinkered with sunlight concentration. In recent decades, several different concentrated solar thermal power technologies have evolved, ranging from a parabolic dish circled by mirrors to tower systems filled with molten salt. The problem with molten salt is that it cannot get hot enough to take full advantage of the power of concentrated sunlight.

CSP With Falling Ceramic Particles

The research team in Newcastle is using ceramic particles as fine as grains of sand that are able to reach ultra high temperatures that are ideal for storing significant amounts of heat. Those heated particles act like a battery, storing energy as heat for up to 15 hours.

“The technology is a smart, cost effective way to store a large amount of high temperature heat for 10 to 15 hours,” said Dominic Zaal, the director of the Australian Solar Thermal Research Institute. He added that traditional CSP facilities are limited by the fluids they use. Molten salt can only handle temperatures of up to 600º C while high temperature oil can only manage 400° C.

However, the ceramic particles the team is working with can endure temperatures of 1000° C. They not only absorb the sun’s heat but also store it, which simplifies the system and reduces costs.

The “falling” part of this method uses gravity to heat these tiny, dark colored ceramic particles less than half a millimeter in size. When dropped from a hopper at the top of the tower, they are heated as they pass through a beam of focused solar energy. As they fall, their temperature can increase quickly from 500° C to 800° C. With more advanced setups, temperatures of more than 1000° C. are possible. Once heated, they are stored in a silo, then used to produce steam for power generation or other industrial tasks.

At first, the particles fell too fast, which allowed them to spread out. That let the sunlight through and reduced efficiency. The answer was a “catch and release” method system that captures them in a trough, slowing them before they are released to fall into the next trough.

CSP & PV Complement Each Other

“CST doesn’t compete with PV solar energy,” Dominic Zall said. “PV gives you power when the sun is shining, whereas CST takes energy from the sun, stores it and then allows the user to use that energy when the sun isn’t shining, such as overnight or on cloudy days.”

CSIRO says CSP with ceramic particles can offer a dependable and green power source that will make it possible for Australia to meet its goal of closing all of its coal-fired generating stations by 2033. At present, those thermal facilities provide 62% of Australia’s electricity.

Image courtesy of CSIRO

As Bill McKibben said recently, the sun can provide all the energy humans will ever need for free. All we have to do is figure out how to harness that energy and put it to use. It will take all the cleverness and inventiveness humans are capable of to make the transition away from fossil fuels. CSP will almost certainly be part of the energy mix of the future.