Fresnel lenses have several uses for self sufficiency. At a web site called Green Power Science, large Fresnel lenses are sold. They can be bought in a tilting frame, much like a full length mirror frame. If you want one for free, you can look on craigslist for old big screen TV's people are giving away. Those TV's have a Fresnel lens in them. If you're willing to haul the TV away, you can get your big lens for free and frame it yourself.
You can purchase one here.
http://greenpowerscience.com/SHOPFRESNELHOME.htmlThese lenses are extremely hands-on, meaning you can't just set it and forget it; you have to be there to operate it to ensure that nothing catches fire and to move it as the sun crosses the sky. But, the sun is free and if you're willing to spend the time using one, there are a lot of things you can accomplish with it.
As mentioned already, you can cook with them. I watched a video of a woman who used one to cook scrambled eggs in a matter of seconds, as well as another where a pasta dinner was cooked using only a Fresnel lens. They are excellent fire starters, of course, capable of lighting a 2X4 in a matter of seconds. They can easily distill water quickly by focusing the beam on a heat exchanger.
There are YouTube videos of people doing these things. Green Power Science has quite a few of them up for viewing and I'd suggest viewing those.
A few things that I haven't seen done yet, but that should be possible, are:
Using a Fresnel lens as the heat source in a wood or coal gasifier.
Using a Fresnel lens as the heat source for a TEG, (thermal electric generator)
Using a Fresnel lens as the heat source to flash steam water, the resulting steam used to power a micro turbine to produce electricity or do other useful work.
Using a Fresnel lens as the heat source for distilling fuel alcohol.
Using a Fresnel lens to heat rocks or clay pots full of sand during the day, then bringing those hot rocks or clay pots in at night for a radiant heat source.
I think survivalists and preppers need to really look into the uses of a Fresnel lens for emergency purposes. Who knows, with enough information and experimentation, maybe we can figure out how to use Fresnel lenses in a more set-it-and-forget-it way. Seems like using a solar tracker is a first step toward that. And perhaps a metal shield that sits much closer to the lens than the focal point, stopping the beam from focusing too hot, might make these things safer, in terms of accidental fires starting.
