(3BL Media/Justmeans) -- Most people think that concentrating solar thermal (CSP) power plants must be large and expensive. Systems are generally based on very large steam turbines with a high overhead cost that can only be amortized over large scale production rates (typically 50-100MW, or more). This amount of power requires thousands of reflectors spread out over a large area. That means it will most likely be sited in some remote area, far from where the power will be used, thereby subject to significant transmission losses.
Aora Solar has developed a different kind of CSP technology that breaks out of this mold.
“Our strategy,” says Zev Rosenzweig, Aora Solar’s CEO and Founder, “is to create CSP that is capable of distributed generation. We take the plant to the user, rather than taking the electricity to the user.”
He calls their system, “micro-CSP technology.”
It is based on a micro gas turbine with a capacity of 100kW, and a compact heliostat (tracking mirror) field, with the heliostats close to the tower. This field directs intensified sunlight on to the solar receiver which is located at the top of the tower. The operating fluid is compressed air, which is heated to 1000 degrees C, and then expanded through a gas turbine.
It’s a hybrid system that can be set to automatically burn biogas or other fuels to heat the air when the sun isn’t shining or if the sunlight isn’t strong enough. This results in a system that can produce renewable power around the clock, 24 hours a day and can continue to produce power even if the sun doesn’t come out for several days in a row.
Rosenzweig considers these systems more nimble than conventional CSP plants, which he refers to as "dinosaurs." Aora's target market is isolated, off-grid villages in developing countries.
“One small plant can easily serve the needs of an entire village on a micro-grid in a manner more cost-effective than individual household PV, without bringing in power from a distant power grid.”
The government of Ethiopia recently signed a memorandum of understanding for several plants after visiting Aora’s demonstration plant in Almeria, Spain. A typical village there, requires around 68 kW, well within the capacity of Aora’s system which seems to be a good fit. Additional units could be added fairly easily.
The compact solar field takes up only about 2,700 square meters, which is about two-thirds an acre. It consists of 45-50 heliostats using parabolic mirrors. These mirrors lose less energy because they are close to the tower. This results in a lower amount of glass per MW, compared to the larger CSP plants.