Solar panels are an attractive source of apparently clean electricity.
But it costs a lot of energy to make a solar panel, they aren't very efficient (turning about
15% of the solar energy that falls on them into electricity), and they don't last long enough to
repay the energy cost it requires to make them.
Then it costs more energy to recycle them.
The efficiencies on solar panels are poorly understood, mostly because of the “lag”
inefficiencies in economic costing of oil-based energy (used to make solar panels), a lag
which makes oil cheaper than it would be if it were priced at its energy utility.
But to make this clear in energy terms: it takes more energy to make a solar panel right now
than it develops during its useful lifetime. So we won't be able to use the energy derived
from solar panels to make more solar panels. Right now it’s a losing game.
I think, however, they are an absolutely crucial part of our long term energy solution and we
need to invest considerable resources in improving them to the point where they net more
energy than they cost.
A BTU is the amount of heat required to raise the temperature of one pound (0.45 kg) of
water 1 degree Fahrenheit (0.56 degrees Celsius).
America consumed 98 quadrillion BTUs in 2003, or 338 million BTUs per person.
That's 926,000 BTU every day for each American.
3,600 joules = 1 watt-hour
11,307 watt-hours per hour or 11.3 kilowatt-hours
The amount of energy consumed every day by each American citizen is the equivalent of
113 lights of 100 watts operating continuously. In a single 24-hour period, the bill would be
for 271,369 watt-hours.
A high-quality 4-ft by 6-ft solar panel can be rated at 300 watts (in an environment with bright
consistent light). That's 12.5 watts per square foot. Sunlight falls on a solar panel for 5
hours per day; so under excellent conditions we can get 62.5 watt-hours per square foot.
We would need 4,342 square feet of solar panel to return 271,369 watt-hours, or 926,000
BTU each day. That's 181 panels of typical 4-ft by 6-ft dimension. Note that in bulk, 300
watt panels cost $2,000 each, so just the panels for this project would cost $362,000 (and
they would last about 15-20 years).
4,342 square feet is a square 66 feet by 66 feet. That is just for one American.
An acre is 43,500 square feet, or almost exactly the amount of solar panel surface area
needed for 10 people.
For 296 million people, we would need 29.6 million acres of solar panel.
A square mile contains 640 acres. The conversion gives us 46,250 square miles of solar
panel.
Virginia 39,594
Pennsylvania 44,817
Mississippi 46,907
New York 47,214
Alabama 50,744
So we need an area the size of Mississippi in a desert.
The oil and gas contribution
A barrel of oil contains 42 gallons.
A barrel of oil equivalent (BOE) is 5,800,000 BTU.
America consumes 20 million barrels of oil per day; or 0.068 barrels (2.8 gallons) per person
per day. This is 391,891 BTUs per day of oil energy, or 42% of the average citizen's energy
basket. If we derived all of our energy from oil, we would be consuming 6.7 gallons per
person per day.
The point here is that 6.7 gallons of oil is equivalent to one day's output from 4,342 square
feet of solar panel.
Gas provides 195,945 BTUs -- 21% of the average citizen's energy basket.
One billion tons of coal are mined and burned in America each year, or 3.378 tons per
person. That's 7,432 pounds of coal per person per year.
Or 20.36 pounds per day, or 0.84 pounds per hour.
Energy / Solar / Resources
Bureau of Land Management
Mother Jones / Bill McKibben
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