People often think that solar photovoltaic panels are OK to put on a roof to cut ones electric bill a little but really doesn’t go far to fill the needs of the nation when it comes to electricity. Or that it’s OK for light weight usages like lighting in parking lots but can’t provide for heavy industries like steel mills. I would like to disabuse those folks of the idea that solar can’t keep us going.
First some fundamentals. Electrical energy is measured in Watt-hours (Wh) or multiples there of. If your monthly electric bill is about a hundred dollars, close to the Arkansas average, you are using a MegaWatt-hour (MWh), which is a million times a Watt-hour. This amount of electricity is available year around from a space about twenty seven feet on a side. It easily fits on a south facing roof. A system like this will not just lower your bill but eliminate it.
Let’s talk about power for heavy industry, and it doesn’t get much heavier than steel mills. Nucor Corporation operates twenty-three steel millsacross the United States producing twenty-two million tons of steel annually employing electric arc furnaces. If we can figure out how to do this with solar panels we can do anything.
It takes about one and a half Mwh electric to produce a ton of steel. On average each plant produces a million tons of steel a year, so we need one and a half TeraWatt-hours;a TeraWatt is a million times a MegaWatt. How much land do we need per plant? It works out to one thousand five hundred acres. This is equal to the land use of less than four average farms in Arkansas. That’s it. The land occupied by four farms in Arkansas will provide enough sunlight to power a steel mill. Cool, huh?
When you look at total electric use in the United States over a year the numbers get really big. The national annual electric use is four PetaWatt-hours; a PetaWatt is a billion times a MegaWatt. So how much land would it take to generate all the electric power we use in the United States? A surprisingly small nine thousand square miles. This is an area smaller than Rhode Island.
The numbers I cite are good for the amount of sunlight in Arkansas using flat plate collectors. If the national power grid originated in Nevada using tracking panels, the area needed is less than five thousand square miles. There are counties in Nevada much larger than that. There is no question that sunlight alone can provide all the electric power we need in this country.
The obvious fly in the ointment is the need for storage when the sun doesn’t shine, or transmission to where the sun doesn’t shine, but both those limitations are under study and are an achievable goal in the near future. And that’s just solar Photovoltaics as an energy source. That amount of energy is available from wind turbines and the potential for geothermal is greater still.