Let's start with hurricanes, with their low-pressure "eye" and multitudes of thunderstorms spinning around it. You probably know that these large tropical cyclones are releasing a lot of energy. But how much is a lot, really?
Well, that depends on how you measure it, but any way you slice it, hurricanes release a phenomenal amount of energy. If we start by looking at just the energy generated by the winds, we find that for a typical mature hurricane, we get numbers in the range of 1.5 x 10^12 Watts or 1.3 x 10^17 Joules/day (this is according to the Atlantic Oceanographic and Meteorological Laboratory.)
This is equivalent to about half of the total electrical generating capacity on the planet! For a single hurricane!
But that's not all, we're just getting started. A hurricane also releases energy through the formation of clouds and rain (it takes energy to evaporate all that water). If we crunch the numbers for an average hurricane (1.5 cm/day of rain, circle radius of 665 km), we get a gigantic amount of energy: 6.0 x 10^14 Watts or 5.2 x 10^19 Joules/day!
This is equivalent to about 200 times the total electrical generating capacity on the planet! NASA says that "during its life cycle a hurricane can expend as much energy as 10,000 nuclear bombs!" And we're just talking about average hurricanes here, not Katrina.