When I wrote my earlier post about parabolic mirror solar projects, I mentioned that I had seen several Google ads for home parabolic mirror kits. My objective with that post was to describe certain large-scale commercial projects, so I didn’t follow up on the home market.
A large-scale solar power plant now operating in Spain and others being planned elsewhere show a great deal of promise. After all, the mirrors work by concentrating heat, not directly creating electricity from photovoltaic cells. It is much easier to store heat than to store electricity. Therefore, the heat can be used to operate a turbine whether the sun is shining at the moment or not.
Unfortunately, building such a plant has high environmental costs. It is not at all certain at this point if the advantages of generating large amounts of clean energy will actually outweigh the costs of clearing vast tracts of land of its vegetation and the heavy use of fossil fuels needed for construction.
I have consistently written that small is better, so I returned to parabolic mirror technology hoping to report on an alternative to solar panels for homes and small businesses. What I found instead is a lot of kits for hobbyists.
One of my roommates in graduate school (the mid-1970s) made it forever impossible for me to scorn what hobbyists can accomplish. He was building his own computer. Every time I opened my mouth, he said there was a possible computer application for that. He predicted that before long, nearly everyone would have their own computer. I thought he was crazy, but look what happened!
I hope someday some entrepreneur working out of his or her garage will find a way to scale parabolic mirror technology for local use. It may never be practical on the level of a single-family house, but it may become useful for apartment complexes, office buildings, or maybe even neighborhoods.
So far, however, it appears that existing kits aren’t generating electricity at all. They’re for solar cookers and hot water heaters. People are building their own systems from kits simply because the technology does not work well enough for commercial applications.
According to an article in Homepower Magazine, thousands of parabolic trough solar collectors were installed in the 1980s for hot water heating, but they all failed to work as planned.
As the sun moves across the sky, flowers track its arc. Troughs of parabolic mirrors must track it, too, in order to be properly aimed to concentrate heat from the sun at any given moment. Eventually, the tracking machinery got dirty, or perhaps froze in bad weather, and stopped working.
Simpler flat solar panel systems worked better at a much lower cost. While advancing technology can surely come up with a dependable way for parabolic mirrors to track the sun, they will always be more expensive and more complicated than ordinary solar panels.
I still hope that parabolic mirror technology can be successful on a scale that doesn’t require removing all the vegetation thousands of acres desert and piping enough water there to operate turbines. For the near future, at least, we can only continue to rely on solar panels in combination with wind power and other technologies for small-scale generation of electricity.
Photo credit: Some rights reserved by frankenstoen. Link to Flickr no longer works.