Those are not limited to oil and coal. Wind, water, the sun, natural gas, geothermal energy, methane produced from biomass (like manure) --all have been and can be put to use as power.
時至今日，電源的種類早已不限於一兩種；除了核能發電所需的鈾之外，石油、煤炭是我們所熟悉的，此外還有風、水，甚至地熱、生質能（如豬的排洩物發酵可產生沼氣）、天然汽和太陽能。