The U.S. National Renewable Energy Laboratory lived up to its name earlier this year by creating the world’s most efficient solar cell. The gallium-indium cell boasts a confirmed efficiency of 40.8%. You might read this and think “That’s terrible”, but that’s just because you don’t really understand how efficiency works.
Let us tell you a little bit about factors involved with energy efficiency. Every singe energy transaction in existence loses juice to friction, heat, and its surroundings. Your body, for example, is about five per cent efficient. For every twenty thousand calories your pull in you barely use one thousand for actually “moving around and staying alive.” The rest is used up in all the en-route steps of chemical processes or poured out of your flesh in the form of heat – and then you have to use more energy to sweat and get rid of it.
How about plants, the worlds ultimate solar collectors. Appalling! All the organic energy on the planet comes via green plants in one way or another and their chlorophyll-chemical conversion barely scores six-point-six percent efficiency. If you scored six-point-six on a test, you’d be fairly unimpressed. And that’s only counting the actual energy-harvesting chlorophyll reaction itself – take into account the rest of the plant required to soak up the sun and the efficiency falls to less than a per cent. Hundreds of millions of years to hone systems dedicated to harvesting the sun and nothing else, and the best nature can manage is less than a percent – those man-made solar panels are beginning to look better already, aren’t they?
In fact, they’re among the best things we’re even able to build. Think of the ultimate in designed systems: the car engine. Beloved of entire cultures and they’ve been around for almost a century, with thousands of engineers honing and refining the system in peace, war and spare time besides.
Thirty-seven per cent. And that’s the IDEAL efficiency – the absolute maximum efficiency that could be extracted if God turned off friction, MacGyver built the camshaft and Haphaestus himself provided perfect metals to construct it with. Real engines only score a twenty per cent conversion of the possible gas power – and solar panels have already beaten what the ultimate engine in a Heaven-bound cadillac could ever achieve.
So yes, 40.8 is good. Very good.