Cool (Earth) Solar

Now this is some cool solar technology. How do you make concentrating solar collectors cheap? Make them out of plastic sheeting and blow them up to the right shape like balloons! That's the basic idea from CoolEarth Solar. The inflatable collectors can be cheap enough to replace every two years, and they are so light, that the structure for mounting them and tracking the sun can also be light and fairly simple. As they say in this PDF presentation, "solar farming" should be taken more literally - make the individual parts cheap and scalable, like growing wheat in a big field, as opposed to growing it in a greenhouse.

Concentrating sunlight onto photovoltaic cells means you need a lot fewer cells. This approach combines clever use of optics and mechanics, with cheap, ubiquitous materials (plastic sheeting, air, a tiny amount of aluminum to coat the reflecting surface). Here's the basic environmental impact (from the notes in the PDF presentation, slide 4):

Our approach is to suspend concentrators on support and control cables stretched between poles. The ground under the concentrators is shaded only by about 10% and remains free for other uses like farming or ranching. Suspending the concentrators also preserves habitat. It is also inexpensive: telephone companies, ranchers, and farmers have already figured out how to set posts cheaply across vast spaces.

Cool indeed.