Where Did the Carter White House's Solar Panels Go?: Scientific American
...it would take producing roughly a square meter of photovoltaic panels or the mirrors for a solar thermal system every few seconds for the next 40 years to harvest one terrawatt of energy from the sun by 2050—using present technologies—according to engineer Saul Griffith of Other Lab in San Francisco. The U.S. presently uses almost four terrawatts of energy a year.
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I’m an engineer, so I know how to use a cocktail napkin to do a sanity check.
Should I trade in my car for an electric vehicle?
My lovely Maxima gets (let’s say) 20MPG. Each gallon of gas contains about 34kW/hr of power. My commute (round trip) is 20 miles. So, I use 680kW to get back and forth to work. Let’s say I get 30% effciency in my use of a gallon of gas in my car. So, I use 204kW/hr for my commute. On average, I can get 300W/hr from a square meter of solar panel (this includes the conversion losses from photons to electrical charge in my car’s battery pack and that we only get 10 hours or so of usable sunlight per day). So, I need 680 square meters of solar panels. Do I want to dedicate this much of the earth’s surface just to my commute? No. Do I want to pay for that many panels and installation? No. If a solar panel lasts 20 years, will I get my money back? No.
You might not like my conversion factors. Use your own. You might be happy with a smaller, lighter car. That’s cool.
When I do buy a hybrid vehicle–I am an electrical engineer–I’ll immediately devise a method for driving power back into the grid…selling cheap petrol-power at highly-subsizided rates…until the green police to stop me or the economy is destroyed by $10 gallons of gas.
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