Off-grid Cooking: How to Make a Fresnel Solar Cooker
By Daniel Barker | Natural News
(NaturalNews) For those interested in living off-grid, solar energy offers one of the best and most readily-available sources of energy. There are many ways to harness the sun’s power for performing a number of tasks, such as creating electricity and heating a home.
The sun’s rays can also be used to cook meals. Building a simple cooker using a Fresnel lens to focus sunlight on a cooking apparatus is easier, cheaper and more effective than you might have imagined.
Fresnel lenses are devices you’ve seen used in many ways, perhaps without realizing what they are or how they work. Essentially a Fresnel lens accomplishes the same thing as a convex lens — it concentrates light by bending the rays towards a focal point, creating a powerful beam that can be projected for long distances, or aimed at something nearby, such as a cooking pot!
The difference between a convex lens and a Fresnel lens is that the latter performs the same function, but with a much smaller thickness. Its design incorporates “steps” comprised of ridges arranged in concentric rings which are progressively angled to focus light towards a central point, thereby eliminating the need for a thick convex lens.
Fresnel lenses are the ones used in lighthouse beacons, but they are also found in the plastic covers of car headlights, taillights and other common devices. The solar cookers I will be discussing here are made from the Fresnel lenses found in old rear-projection wide-screen television sets.
They are easy to find on eBay, where you can purchase one very cheaply, or on Craigslist, where you will often find them being given away. You may also see one of these old TV screens discarded on the side of the road, waiting to be picked up by the trash disposal trucks. You may already have one laying around your garage or storeroom.
Once you’ve found or purchased your own Fresnel lens, making a frame for the lens and a stand for holding the cooking apparatus (frying pan, dutch oven, etc.) is a relatively simple undertaking and you may already have all the materials you need just lying around the house.
There are many designs to be found on the Internet, some with detailed plans and others that just give a general idea of how they work. There are lots of YouTube videos on the subject, as well.
http://graywolfsurvival.com/84068/solar-diy-building-fresnel-solar-cooker/