"I wonder how much embedded energy is there in that giant fresnel lens. These things are notoriously expensive." It is basically a transparent sheet of plastic

"I wonder how much embedded energy is there in that giant fresnel lens. These things are notoriously expensive." It is basically a transparent sheet of plastic with some of the plastic carved out. So likely not much energy. They are only expensive to buy in large, because there is not really a market yet, except hobbyists.