Solar power may not be the end-all be-all covering our energy needs, but it is clean, which makes it a good investment into our future.
On problem, however, has to do with the efficiency of solar power. According to research, an oil well puts out about 27 W/m2 (watts per square meter), while PV (photovoltaic) solar panels, generate just 6 W/m2, meaning that lots of lots of area is required to generate enough power to outweigh an equivalent fossil-fuel source. Of course, this explains why renewable energy sources aren’t taking over for non-renewable energy sources.
We’ve talked about space-based solar power before, and most figure the technology is many decades away. PV solar panels themselves are nothing new, and neither are satellites bearing PV solar panels. So, the idea of a space-based solar power generator, placed in geosynchronous orbit, actually isn’t that far-fetched. Solar power generated in space has a couple of advantages, such as the elimination of efficiency-reducing day cycles, dust, and weather. On the other hand, once that power is generated, we can’t just plug in a 36,000-km extension cord, can we?
Taking place of the extension cord from our space-based solar power generator would be microwave energy, according to JAXA (Japan Aerospace Exploration Agency), a 1 GW solar power collector in space would transmit a 5.8 GHz microwave signal on the order of 1 KW/m2 power intensity. Of course, such a microwave beam would be about 100x higher than save human exposure limits of 10 W/m2, so JAXA couldn’t put the receiving antenna just anywhere. Instead, a manmade island, 3 km in diameter, would function as a receiver, possibly up to 80% efficient, which would convert microwave energy to DC power, and then to AC for the power grid. JAXA expects to have a 100 kW demonstration in place by 2020, possibly getting up to 1 GW by 2040.