Typically they produce tens of billions of watts of electrical power, but there is no known way to harness this energy because of the vast scales over which it is produced, and the very low density of this power. Even the most powerful aurora at 1,000 billion watts are spread over millions of square miles of land surface. The actual power of such a storm is less than a megawatt per square mile. This still sounds like a lot, but it is about equal to a watt per 25 square feet - hardly a goldmine of energy compared to solar energy. It would be like trying to harness the mechanical energy of a flock of mosquitoes!

If you want to keep up with the actual daily/hourly power output of aurora, have a look at the NOAA/POES satellite website. They produce plots like the one above which give the total equivalent power of auroral activity in the north and south hemisphere. The numbers in their archive show a range from 4 billion to over 900 billion watts of power in the northern hemisphere alone. The total world production would be about twice this amount because there are nearly identical aurora in the southern hemisphere too.

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