There’s something about solar energy that turns otherwise
intelligent brains to mush. Paul Krugman, the celebrated Nobel
Prize-winning economist, has now joined the crowd.
In an op-ed last week entitled “Here
Comes the Sun,” Krugman invoked Moore’s Law, of Silicon Valley
fame, to marshal the case that solar energy will soon be taking the
place of coal, oil, gas nuclear and all those other nasty things.
Here’s the way he went about it:
For decades the story of technology has been dominated, in
the popular mind and to a large extent in reality, by computing and
the things you can do with it. Moore’s Law — in which the price of
computing power falls roughly 50 percent every 18 months — has
powered an ever-expanding range of applications, from faxes
to Facebook.
Our mastery of the material world… has advanced much more
slowly.… But that may be about to change. We are, or at least we
should be, on the cusp of an energy transformation, driven by the
rapidly falling cost of solar power.… [A]s a blog post at
Scientific American put it, “there’s now frequent talk
of a ‘Moore’s law’ in solar energy,” with prices adjusted for
inflation falling around 7 percent a year.
Well, serves you right for relying on Scientific
American. As anyone who has read that once venerable magazine
of late can tell you, it’s much more about politics than
science.
In the first place, Moore’s Law has nothing to do with
price. It’s about information. Literally, it
describes the number of components that can be placed in an
integrated circuit. Moore noted in a 1965 paper that the figure had
doubled every two years from 1958 to 1965 and thought it would
probably continue at that pace “for at least ten years.” In fact
it’s continued that way ever since and has now accelerated to once
every 18 months.
Moore’s Law is not a Law of Nature, like the Laws of
Gravity. It is only an empirical observation about our rate of
innovation. We may eventually run out of room at the bottom. Moore
himself predicted in 2005 that in twenty years we would reach the
dimensions of individual atoms and progress might end — unless we
started working at the subatomic level. Other commentators have
pushed the limits even much further out.
So what does all this have to do with solar energy? Well,
nothing. “It is a common (but mistaken) belief,”
says the
Wikipedia page, “that Moore’s Law makes predictions regarding all
forms of technology, when it has only actually been demonstrated
clearly for semiconductor circuits.”
Not that people haven’t tried. Al Gore started the whole
thing in The Earth in Balance when he referred to solar
collectors as “small flat panels of silicon or similar
materials that are designed to produce currents of electricity
[emphasis added].” Somehow he got the idea that because computer
chips and solar panels were both made from silicon, they would
follow a similar trajectory. Even Silicon Valley entrepreneurs and
venture capitalists seem to have gotten the bug around 2004 when
they jumped into “alternate” technologies, proclaiming they would
do for energy what they had done for computing.
Moore’s Law is about
information, not
energy. The reason computer chips have
gotten smaller and smaller is that we keep using less
and less energy to store the same amount
of information. Think of each logic gate as a light
bulb that can be turned on and off to represent a “1” or a “0.” The
original computers used vacuum tubes that consumed lots of
electricity. Now we use transistors printed on microscopic circuit
boards that require only the faintest electrical current. We may
eventually get down to the level of individual electrons, but the
point is that all this is accomplished by using smaller
and smaller energy differentials to represent the
ones and zeroes.
When you go looking for energy,
however, you can’t do that. You can’t go down, down, down into the
microcosm using less and less energy to produce more
and more energy or even the same amount of energy.
Energy is energy. You’re stuck with what’s available.
With solar energy this is all very easy to calculate. The
average amount of solar energy falling on a square meter of earth
is 400 watts. It will never be any different. With present
technology, we can convert 25 percent of this to electricity. This
means powering a 100-watt light bulb on a space the size a card
table. If we could raise this conversion to 35 percent — a 40
percent increase — it would be a technological marvel. That’s a
lot different than doubling every two years.
What that means is that the only practical way to produce
more solar energy is to build bigger and bigger projects. It now
takes a facility of about 20 square miles to produce 1000 megawatts
— the same output as a large coal or nuclear plant. The Department
of Interior is talking about covering 400 square miles of Western
desert with solar collectors to produce the output of about ten
reactors. We’ll see what the environmentalists have to say about
that. All this works in America because we have lots of empty
space, but it is not likely to work in densely populated
areas.
There is always the possibility of rooftops. This has
potential, particularly since solar peaks at the right time, on hot
summer days when air conditioning strains the grid. Solar could be
very useful in helping utilities meet the perennial problem of
supplying peak demand. But all this is not going to be cheap.
However prices may be dropping, they are not going to follow any
exponential path. Solar electricity is now three times as expensive
as nuclear and five times the price of gas. Even if it becomes
competitive, it is only available one-quarter of the time. It won’t
be replacing nuclear, gas, or coal any time soon.
After I wrote my book, Terrestrial Energy, in
2008, I started giving a Power Point speech in which I pointed out
the staggering land requirements of so-called “renewable” energy. I
used a 2005 quote from Oliver Morton, news editor of
Nature, who had proclaimed, “If scientists can discover a
Moore’s Law of solar energy, it could change the world.” Lately,
however, I have been leaving it out because it seemed too outmoded.
It wasn’t fair to be holding Morton responsible for this early
naïveté.
Thank goodness for Paul Krugman. Now I don’t have to rely
on Oliver Morton anymore.
