But even efficient fuels cost money—so the less of them you burn, the better. Compared to using age-old technology such as an open-coal fire, most modern heating appliances are actually pretty efficient; look at the red bars in the chart below and you'll see that, for every joule (...
In theory, if you could turn about seven billion hydrogen atoms completely to energy, you'd get about one joule (that's about as much energy as a 10-watt lightbulb consumes in a tenth of a second). Remember, though, these are just ballpark, guesstimate numbers. The only point we ...