Space Solar Power

Number 10 in Top Ten Blatant Misapplications of Science!

Solar power has many quirks, but by far the biggest, which literally overshadows (har har) the rest, is that the sun doesn't shine at night. The function of solar power plants limits them answering peak loads only during the day, as they cannot function as baseload plants. They also have the added issue of uncontrolled variable production due to weather conditions, much like wind power - although this issue is somewhat mitigated by proper siting of the plants.

A logical solution to this condition it to simple move the solar plants somewhere were the sun always shines, and without variation - space. An added benefit would seemingly be the the lack of attenuation of the energy by earth's atmosphere, thus providing more energy. The power could then be beamed down as microwaves to a receiving station on the earth's surface, and distributed from there in a normal matter.

So why not starting shunting space-power satellites into orbit?

Well, there are some MAJOR challenges, both economic and technical. To make them produce any significant power, the stations would need to be very large, on the order of football fields in size. This would make them heavy, and at $15,000 a pound, its starts to get a little out of hand. The second problem is construction and maintenance. They would need to be assembled and fixed in orbit - and remember, the simple repairs to the hubble space telescope, an object only the size of a school bus, cost over $1.5 billion and took almost a year to get fixed. The same peice of hardware, located on the ground, could be fixed for probably less than 1 million.

So lets assume we somehow solve the economics issue by providing dirt-cheap space travel. Then enters the technical issues. Remember the proposed efficiency gains? Well the station may be receiving more energy than it would on earth, but the microwave beam still has to travel through and be attenuated by earth's atmosphere, so there goes that advantage. To actually be able to send power to the same receiving station, the satellite would have to be in geostationary orbit, which is over 22,000 miles out. At this point you run into a beam divergance issue, it would be nearly impossible to focus the microwave energy into something narrow enough to not require a massively large collector on earth, probably as big as simple solar power plant. The technology does not exist yet to make microwave lasers, so we've hit a bit of a wall. The other problem is that solar cells (if they were to be used), actually have shorter service lives in space due to degradation from cosmic and solar radiation which is normally filtered by atmosphere. We could just use mirrors and steam generators instead, but that just makes everything heavier, and require more maintenance, because of the introduction of moving parts.

There are a lot of parallels between the notion held by advocates of space power and Nikola Tesla's dream of broadcasting wireless power. We don't have "magnifying transmitters" sending us power because of the inverse square law - power drops off at the square of the distance. This is a difficult law to overcome, not just a theory :)

As it might be evident this idea actually introduces more problems than it fixes. It requires cheap space travel, microwave lasers, and cheap solar cells, none of which exist today.

Since storing electricity at "grid level" is economically questionable, the simplest way to solve the "night" problem is to stagger the terrestrial stations at evenly spaced intervals on the planet, thus relying on the forward stations to power the darkened areas. There is no new technology to be developed, someone just needs to build it. A whackier but still cheaper than space satellites idea would be to float the solar stations on huge hydrogen blimps which could float above and avoid clouds, and beam the power only a few hundred feet in the form of concentrated light to ultra-efficient high temperature solar cell collectors the size of swimming pools. If this sounds silly to you, then there is no reason the the space idea shouldn't.