Solar forge

A solar forge is a device that uses the power of the sun to melt materials, such as asphalt. A large Fresnel lens, usually rectangular and several feet long on each side, is positioned as a lid of a hollow standing cylinder. The lens focuses the sun's radiation to a point inside the cylinder, where the material to be melted is placed. The effect is the same as a magnifying glass used to burn a dry leaf, except that the heat achieved is much greater.

Solar forges work best in desert areas where there is plenty of sunlight. They are dangerous to approach because they intensely concentrate heat and light from the sun. A safe way to handle the danger is to cover the lens when not in use. Solar forges are easy to build, because they consist of only two parts. Other optional parts are: a cover, a pollution-control device (for the smoke), a vent, a temperature gauge, protective fire-proof clothing, and gas masks. Solar forges have the benefit of cheap construction and no fuel cost, unlike other forges.