Solar Based Solar Energy

A major drawback of most if not all sustainable sources of energy is the matter of intermittency. Power can’t be generated by wind turbines if the wind doesn’t blow, and solar panels don’t generate power when the sun doesn’t shine.

There are three ways to deal with this. One is to simply expect to use power when it is available. This is impractical for homes or hospitals or industries where power is necessary 24/7, but it is conceivable that certain industries could run their industrial processes when power is available. Sources such as wind and solar are intermittent, but reliably so. A major problem with this strategy is that expensive equipment can’t be used for sizable amounts of time, making the industry less efficient and therefore less competitive.

The obvious solution is energy storage for leveling the availability of power, and there are a number of different strategies. Pairing energy sources to level access to power may be possible in some cases. In some areas the wind blows more at night. This could be combined with daytime solar PV. Actually this is already occurring to some degree via our electrical grid that utilizes both wind and solar inputs.

The holy grail of sustainable but intermittent energy is inexpensive grid scale battery storage. This is a major forefront of sustainable energy research today. Some Japanese researchers are taking another tack however. What if you could find a place to put solar panels where the sun always shines, with no shadows or clouds, just sunlight 24/7. No problem, just head out into space about 20,000 miles. Solar panels are already hard at work powering hundreds, even thousands of satellites and of course the international space station.

The Japan Aerospace Exploration Agency (JAXA) has a 25 year plan to develop gigawatt scale solar panels in space and then beam that energy back to earth. For perspective the average nuclear power plant produces a little less than a gigawatt. The two reactors at Arkansas Nuclear one combined output is about 1.8 Gigawatts.

This will be a BIG project. To produce that kind of power requires an array of solar panels that weigh on the order of 10,000 tonnes and covers an area of a couple square miles, but this is the easy part. Getting that power back to earth is the really tricky part of the plan. The idea is to beam the power back from space via microwaves. Satellites in geosynchronous orbit would point a sending device towards an earthbound antenna which would absorb the microwave power, then convert it to electrical energy that could be sent to grid along with all the other energy sources.

We use microwave ovens to heat up cold cup of coffee, but in this application the power is sent only a few inches, not tens of thousands of miles. Microwaves are sent long distances in the form of radar, but the relative power level is extremely low. To beam relevant amounts of power tens of thousands of miles is the real challenge.

So far testing has only involved sending kilowatts of energy over a fraction of that distance. Stay tuned.

RIP David Bowie 1947-2016

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