Temperature gradients are the basis of thermoelectric generators. The potential difference allows for the creation of electrical current. What does this have to do with Tornadoes?
One scientist, Louis Michaud, plans on harvesting a by-product of large scale temperature gradients – tornadoes – to generate electricity. The core of his proposed power plant, called the Atmospheric Vortex Engine (AVE), will generate a tornado and harvest energy from the resulting air currents. In order to supercharge and sustain the vortex, the power plant will feed it waste heat generated by the turbines. This creates a cutoff switch in case of emergency, such as if a giant, permanent tornado next door to your house escapes its earthly bondage to reign destruction upon its human oppressors. If the waste heat is cut off from the vortex, the vortex dries up.
Early calculations by Michaud predict a possible 200 megawatt output from such a power plant, enough to power a small city. (source)