Republicans and Democrats are currently at loggerheads in the
Senate over a bill to require the nation’s utilities to draw a
fixed percentage of their electricity from so-called “renewable
energy.”
The Democratic bill, sponsored by Democratic Energy Committee
Chairman Dave Bingaman, of New Mexico, would have utilities get 15
percent of their electricity from wind, solar and other “renewable”
sources by 2020. This version seems to be one vote short of beating
a promised Republican filibuster.
Republican Senator Pete Domenici, also of New Mexico, has
offered an alternate bill that would keep the same requirement but
allow nuclear power and — bizarrely — “clean coal” to be included
under the rubric of “renewable.” That bill was soundly defeated,
56-39, with seven Republicans joining the Democrats to defeat the
measure. A special committee is now trying to work out a
compromise.
There is only one small point that makes this whole discussion
rather irrelevant. According to the laws of physics, there is no
such thing as “renewable energy.”
The Second Law of Thermodynamics, developed during the 19th
century, is said to be the only principle of Newtonian physics that
survived the Einsteinian revolution. Therefore it is worthy of
respect. The Second Law is expressed in a variety of ways —
“entropy,” “disorder,” the “dispersal of energy,” the
irreversibility of time. For the sake of this discussion, one of
its principal corollaries is more than sufficient — “Energy cannot
be recycled.”
The First Law of Thermodynamics (actually discovered after the
Second Law) says that energy is always conserved and never
destroyed. This seems to suggest perpetual motion. If we could only
keep recycling the same energy, we would never run out.
The Second Law — first posited by Sadi Carnot in 1824 —
contravenes this possibility. It holds that as energy is used
to do work, some of it inevitably becomes irrecoverable.
Energy is never destroyed. It transmutes from one form to
another — heat to mechanical motion to electricity to mechanical
motion and perhaps back again to heat. In the process, however,
some of the energy inevitably becomes inaccessible as
“waste” or low-grade heat. Once dispersed, this energy achieves a
state of high disorder or entropy. It cannot be reused, renewed, or
recycled because it would take more energy to reassemble it
than could be recovered.
The gasoline in your automobile engine, for example, transforms
into mechanical motion. As it is consumed, however, some energy is
inevitably thrown off as engine heat or friction against the road.
Eventually all the momentum of your car will eventually be
transformed into low-grade heat. The energy is still out there but
it cannot be recycled or renewed. Therefore you will need a
refill.
Calling some sources of energy “renewable” suggests that they
can be used over and over, as opposed to other forms of energy,
which will eventually run out. This is very misleading. What we
really mean is that some forms of energy are
inexhaustible, at least for our purposes. The energy of
the sun is inexhaustible with respect to life on the planet. But it
is not infinite. The solar energy falling on New York
would not be enough to run the city, even if 100 percent of it were
utilized. Therefore it must be collected elsewhere and transported,
which itself consumes energy. The sun may come up day after day,
but it does not provide unlimited amounts of energy.
Most “solar energy” actually comes to us in indirect forms,
where the gathering and transporting is the limiting factor.
Hydroelectricity derives from the sun’s power to evaporate water
and return it as rain. Yet there are only so many good dam sites.
Hydro power supplied 20 percent of our electricity in 1980 but only
10 percent today, since most of its potential has been used. Wind
comes from the sun’s uneven heating of the atmosphere, but wind
power is highly dispersed and must also be gathered and
transformed. The wind is unpredictable and cannot be relied upon
for large amounts of dispatchable electricity. Once wind reaches 20
percent of a grid, it begins to create voltage balance
problems.
Direct solar electricity is free for the taking but does not
arrive in very large amounts. The solar energy falling on a
square-meter card table is enough to power one 100-watt light bulb.
At best it could probably provide our indoor lighting. It is not
enough, however, to run industrial machinery or highly
sophisticated electronic networks. The great advantage of solar
electricity is that it is strongest when it is needed most — on
hot summer afternoons when electrical demand peaks. Solar
electricity could definitely relieve natural gas peaking plants in
powering our summer air conditioning.
Fossil fuels are stored solar energy and renewable over the
geological ages. We just don’t have time to wait around for them to
renew. Oil and gas supplies are somewhat limited and now lie mostly
in countries that are politically unpredictable. We have so much
coal in the U.S. we will probably never run out, but it is the
prime source of air pollution and greenhouses gases. “Clean coal”
is extremely expensive and will create huge problems in trying to
bury whole oil fields worth of liquid carbon dioxide deep in the
earth.
“Biofuels” are a gray area. They are “solar” and “renewable” but
only within very strict limits. Sunshine is just one contributing
factor. Much more important are land, water, fertilizer and other
agricultural resources. Growing energy will compete with growing
food. Nor are biofuels “carbon neutral.” Burning this year’s crop
instead of leaving it in any of the numerous carbon sinks — plant
material, soil, the food chain — increases the amount of
greenhouse gases in the atmosphere. Calling biofuels “carbon
neutral” is just poor accounting. They will both strain
agricultural resources and contribute to global warming.
There is one other source of energy that is close to being as
inexhaustible as the sun. That is nuclear power, which might be
called “terrestrial energy.” Our planet generates huge amounts of
heat. The temperature in its interior — 7,000 degrees C. — is
hotter than the surface of the sun. What is the source of this
heat? Some of it comes from the pressures of gravitational
collapse, but almost half is generated by the disintegration of two
tiny elements, uranium and thorium.
Terrestrial energy is tapped at geothermal sites, where heat
from the earth’s molten core comes in contact with groundwater. We
perform this same heat exchange in what is called a “nuclear
reactor.” A nuclear plant is simply the duplication of a geothermal
site under more controlled conditions.
Terrestrial energy is not infinitely renewable, but then neither
is any other source of energy. It does not rely on solar energy
stored in carbon bonds and therefore does not put carbon dioxide
back into the atmosphere. It is about as “green” as energy can get.
It can probably stand by itself but is definitely worth including
in any portfolio of “clean, renewable energy.”
