Check out this solar-powered 3D printer
Yo dawg, I heard you like solar power, so I put some solar power in your 3D printer so you can solar power while you 3D print.
The Solar Sinter, an art project by Markus Kayser, is probably not actually going to replace energy-hog fabrication processes. It's more of a concept piece, but it's a pretty spectacular one that beautifully demonstrates the awesome power of the sun. Kayser uses the strong sun in the Sahara desert (yes, contrary to appearances, he is not on the Black Rock playa) to melt sand into layers of glass, building gnarled glass objects that look more like sandstone than like anything you'd get at Crate & Barrel. This is probably not going to be the future of glassware, granted, but if anyone doubts the sun's ability to provide truly massive amounts of energy, just show them this video of sand bubbling under the concentrated solar rays.