A team at Australian National University (ANU) have set a world record for efficiency for a solar concentrator dish, achieving a 97 percent conversion of sunlight into steam.
By designing and building a new receiver for the solar concentrator dish at ANU, the scientists were able to half the losses, and achieve an unprecedented conversion efficiency. The breakthrough, which could be applicable to power stations, could lead to the generation of cheaper base-load electricity from renewable energy, helping lower carbon emissions that cause global warming.
According to Dr John Pye, one of the ANU engineers, the computer model predicted an "alarmingly high" efficiency for the design.
"But when we built it and tested it, sure enough, the performance was amazing," he said.
Concentrating solar thermal systems use reflectors to concentrate sunlight in order to generate steam, which then drives conventional power station turbines. It can be combined with efficient heat storage systems and can supply power on demand at a significantly lower cost than solar energy from photovoltaic panels that has been stored in batteries.
The global concentrating solar thermal capacity has grown by a factor of 10 in the past decade, so any moves to reduce the cost of energy generation using this method is of commercial interest.
"Our aim is to get costs down to 12 cents per kilowatt-hour of electricity, so that this technology will be competitive," Dr Pye explained.
"This new design could result in a 10 percent reduction in the cost of solar thermal electricity. I'm optimistic that our technology can play a role in the grid, by helping to provide power at night without fossil fuel power stations running."
The ANU solar concentrator is the largest of its kind in the world, at 500 square metres large. It focuses the power of 2,100 suns onto the receiver, through which water is pumped and heated to 500 degrees Celsius.
The new, ultra-efficient receiver design is a cavity that resembles a top hat with a narrow opening and a wide brim. Water pipes spiral around the underside of the brim and up into the hat.
The sunlight is focused onto the pipes, heating the water as it enters at the brim and spirals up into the cavity. The water reaches peak temperature in the deepest reaches of the cavity, which minimises heat loss. Any heat which leaks out of the cavity can be absorbed by the cooler water around the hat's brim.
The power of the concentrated radiation is so strong that it can damage componentry if not aligned properly, so the team calibrated the dish using the full moon.