Assumptions: The Three Gorges Dam is rated at its full design capacity of 18 gigawatts. A nuclear power plant is postulated to be the equivalent of a 1.1-GW unit at the Diablo Canyon plant in California. A coal plant is one rated at 500 megawatts. A wind turbine is one with a 100‑meter blade span, and rated at 1.65 MW. A solar panel is a 2.1‑­kilowatt system made for home roofs. In comparing ­categories, bear in mind that the average amount of time that power is produced varies among them, so that total energy obtained is not a simple function of power rating.