Fireflies light up summer lawns at dusk through chemical reactions, which take place between a light-emitting substance and its related enzyme. Luciferin and luciferase, respectively, could provide a natural, electricity-free glow for ambient lighting and other uses. But previous experiments to this end have not yielded very bright light.
As the world — and its landfills and water treatment plants — get more and more crowded, future houses will have to cut down on their waste. Or they could just repurpose it. For instance, they could use household sludge to feed bioluminescent bacteria to light up a room. It’s so simple! Really!