Last year in October, we talked about University of California’s specially contrived composite nanomaterial that could convert a whopping 90 percent of sunlight to usable heat energy (that is further used for generating electricity via steam-based turbines). Unfortunately, the said technology has still not crossed the threshold of development phase. But when it comes to the real deal of practical efficiency, the above pictured solar electric project based in the Kalahari Desert, South Africa, might just take the cake. Designed as a small-scale Concentrated Solar Power (CSP) system by Ripasso (a Swedish energy company), the installation has been tested and found to have impressive efficiency figures that pertain to 34 percent conversion rate of sun’s light into pure electricity (not heat). For comparison’s sake, a conventional photovoltaic system accounts for around 23 percent efficiency, which is further reduced to 15 percent before being used by the grid.
Quite intriguingly, the setup in question here is based on the Stirling engine – which was originally developed in 1826 by Scottish engineer and clergyman Reverend Robert Stirling. Designed as a closed-cycle regenerative heat engine, it was basically envisaged as an alternative to the renowned steam engine – with utilization of enclosed gas that could drive pistons and turn a flywheel. And now, after 189 years, the system is once again back into the unexpected limelight courtesy of human kind’s dabbling with renewable sources of energy.
In terms of its working scope, the small-scale CSP system combines the aforementioned Stirling engine with a parabolic mirror. As we can make out from the images, the 1,000 sq ft automated dishes function as the so-called ‘concentrators’ by focusing the sun’s energy into a singularly heated point, which in turn fuels the Stirling engine. When translated to figures, the setup has the enviable capacity to produce around 75 to 85 megawatt hours of electricity a year. This is good enough to power around 8 typical American homes in a year. And just to give a perspective, a similar quantity of electricity produced by a coal-based thermal system would have resulted in emanation of around 81 metric tons of carbon-dioxide in the atmosphere.
Finally, we should also remember that this particular CSP system totally eschews water for producing electricity – thus going against the convention of regular CSP systems. This potentially cuts down on the resources required for the installations, especially in the context of arid regions like the Kalahari Desert and even present-day California.
Via: Inhabitat / Images Credit: Ripasso