Wind

From EcoReality

Wind energy, like all energy sources except nuclear and tidal, is a form of solar energy. The sun shines on oceans and on forests, on rocky mountains and on snowfields. These surfaces absorb different amounts of energy, and this differential heating causes convection currents to flow. We call this wind.

Wind pushes on things. Humans have been using this since very soon after they learned to build things that could float across the water. And not long after that, we learned how to grind our grain with the help of the wind.

Today, wind power is the fastest growing alternative electric power source. But it still produces less than 1% of energy in North America.

But the wind does not blow all the time, and when it does, it's typically not steady, but gusty. This would not be so bad if doubling the wind speed merely doubled the power that had to be dealt with, but wind energy is proportional to the volume of the swept area, so doubling the wind speed results in eight times as much power. Or try this on: if the wind speed goes up ten times, the power is 1,000 times greater!

You might think it's a good thing to get such an increase in power for such a small increase in wind speed. But it's fiendishly difficult to built wind plants that can function over such huge ranges. You end up either getting very little energy at low wind speeds, or you have a machine that self-destructs in even moderately high winds.