Gram for Gram, Solar Is Ten Times
More Powerful than Nuclear
Jan 10, 2011 - Susan Kraemer
A novel way of comparing solar power
with nuclear power finds that solar easily bests
nuclear. Ken Zweibel has an analysis at The Solar
Review that compares the two kinds of electrical
energy, in terms of how much power is packed into
each gram of its respective material: cadmium telluride,
He provides data showing that CdTe thin film solar
power (using cadmium telluride) takes ten times less
PV material to make 1 kilowatt hour of electricity,
than nuclear uses of uranium, to make an identical
1 kilowatt hour of electricity.
This is even comparing the two as if solar "used
up" each gram of cadmium telluride the way that
nuclear power uses up its uranium fuel (pretty much
- some can be recycled, theoretically). But of course,
solar doesn't burn up fuel. You can get electricity
from the same grams of PV material for at least thirty
years, and then the material can be recycled and
still used again.
By contrast, the equivalent grams of nuclear uranium
must be replaced with newly mined uranium once the
first has yielded its energy.
Here's his math. It takes 12 grams of CdTe to make
a one square meter solar thin film module.
"In a year in an average US location, we harvest
about 11% x 1750 kWh/m2-yr, or 154 kWh/yr (after
accounting for another 20% in losses)" he notes.
So we need 0.08 of a gram per kilowatt hour for
one year's supply of electricity. But that assumes
we've used up the gram by the end of the year.
"But wait!" he cries. "We don't burn
PV modules, and they don't die after one year - warranties
are about 30 years, so this is really one thirtieth
of that, or 2.6 milligrams per kWh".
So, compared with nuclear, solar packs a punch:
using one-tenth as much material to make the same
But check out the comparison to coal. According
to his calculations, even assuming just thirty years
use, then tossing the solar, the thin film photovoltaic
material uses just five millionths of the weight
of coal needed to make the same kilowatt hour of
"Compared to coal, of course, the numbers are
out of this world. These differences in resource
needs bear on the ultimate sustainability of the
PV in comparison to other more resource-intense energy
Indeed. Solar looks to provide us with not just
a cleaner, safer and healthier form of electricity,
but also, one that is much more sustainably mined.
It takes just a fraction of the stuff from the earth
that coal or nuclear takes.