You can make candles from beeswax, which is expensive, or tallow, which is made of cows and thus bad for the environment, but I’m going to make a wild guess and say that your bog standard cheap candle is ultimately made out of some kind of hydrocarbon. So, in our glorious net zero future, when the power grid has a little oopsie we’ll be huddled around a little blob of oil for light and heat….