Combustible fuels have been around ever since humans realized that they could burn wood. Over time, we discovered new energy sources—fossil fuels, which still dominate the world’s energy portfolio. But what if we could find another fuel source, one that was abundant, easy to procure, and people were happy to give it away? Something like municipal or agricultural waste? One fuel, called hydrochar, which is a proposed replacement for coal, can be made in a laboratory from waste using water and some low-cost catalysts. It might be the answer to a burning energy question.