Based on reputable estimates, as of 2006, total world energy consumption has just topped 400 quadrillion BTU’s. Check the Infoplease website for a good summary of world energy consumption by region and by decade, including forecasts.

If it takes 3,413 BTUs to equal one kilowatt-hour (it does), and if you assume all energy consumption in the world is electrical, this would mean that in 2006 the world will consume about 13,370 gigawatt-years of electricity.

There are many critics of photovoltaic power, and one of their claims is you couldn’t possibly squeeze enough of these panels onto the planet to fulfill humanity’s energy needs. The purpose of this entry is to prove that criticism dead wrong.

How much panel area would be necessary to power the entire world with nothing but photovoltaic energy? How large a panel would it take to generate 13,370 gigawatts of electric power, all year around?

First of all, triple the power requirement, under the assumption that you only will get 8 hours of full sun per day. In reality the output of photovoltaics is somewhat better than that, but let’s satisfy the skeptics and stay conservative.

This means you will have to generate not 13,370 gigawatts of energy, but 40,109 gigawatts - all using photovoltaic panels. If you spread them all over the earth, in every time zone, you’ll be fine. How much land would it take?

Assuming 10 watts per square foot - and that is definitely conservative nowadays - you would need to cover 143,872 miles of the earth’s surface with photovoltaic panels. Does that sound like a lot? It isn’t.

This area equates to only .2% of the 56 million square miles of land on earth. It equates to barely one acre per square mile, or for our metric readers, about one quarter of one hectare per square kilometer.

Put another way, enough photovotaics to provide 100% of the energy currently produced from all sources in the world in 2006 would equate to only 668 square feet of photovoltaic panel per person, or not quite 70 square meters per person.

The entire world could be powered using photovoltaics while consuming no space other the rooftops of the world. The algebra is immutable.

Read The Coming Boom in Photovoltaics for an explanation as to why the price of photovoltaics is about to plunge, and read The True Cost of Photovoltaic Power for an explanation as to why photovoltaics are already a compelling long term investment, even at today’s prices and without subsidies.