Today, carbon dioxide and energy. The University of
Houston's College of Engineering presents this
series about the machines that make our
civilization run, and the people whose ingenuity
created them.
A carbon atom can combine
with either one or two atoms of oxygen. Carbon
monoxide is pretty reactive. It readily
burns in oxygen to create carbon dioxide,
or CO2. CO2 is completely
stable. It won't burn, and you can breathe it all
day with no ill effects. You do breathe carbon
dioxide, all the time.
The major component of any fossil fuel is carbon.
It forms seventy-five percent of methane, the major
component of high-grade natural gas. Carbon forms
eighty-four percent of octane, which typifies most
gasolines. It forms eighty percent of good
anthracite coal.
Now here's the catch. Since each carbon atom joins
with two heavier oxygen atoms, CO2
molecules are much heavier than the carbon in
fuels. Each pound of fuel yields almost three
pounds of CO2. That takes some
digesting. Our first reaction is, "It's only a gas;
it surely can't amount to much." But each gallon of
gasoline produces twenty pounds of carbon
dioxide.
Our consumption of fossil fuels has now caused the
CO2 content of Earth's air to be higher
than it should be. It's certainly impacting our
climates. How much is subject to a pretty fierce
debate, but global temperatures are definitely on
the rise. While better analysts than I try to
determine exactly what part of the rise comes from
CO2 greenhouse effects, we'd be crazy
not to look for ways of reducing the CO2
in our air.
We leave it to plants to turn carbon dioxide back
into burnable carbon and oxygen. So far, lowered
fuel consumption seems to be the only answer to
increased CO2 levels. Cleaning up
emissions won't get rid of it. And the only way to
avoid producing it is to quit burning carbon. But
now I find a set of odd new technologies in a
recent Mechanical Engineering magazine.
These are means for collecting CO2 and
storing it away much as we do with nuclear waste.
One trick is to gather in CO2, compress
it, and pump it into the ocean bottom, where the
pressure holds it in liquid form. As a liquid, it's
much heavier than water and will stay on the
bottom. A plant in the North Sea is presently
burying 2800 tons of CO2 in the ocean
every day. That's roughly the output of a big
140-megawatt coal-fired power plant.
Another process converts CO2 into a
solid carbonate. The product is a brick that's
one-fifth CO2. The bricks are still far
too expensive to be practical, but they get me
thinking. While I worry about these so-called
sequestering methods taking carbon out of
circulation, they might just offer a temporary stay
-- as we keep hesitating to use nuclear and
renewable energy.
In any case, my aim today is modest. I just want to
offer CO2 as a contemplation object -- a
focus for our thoughts as we continue the ongoing
struggle with rising energy demands and the
terrible problems they bring with them.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
work.
(Theme music)
J. Winters, Carbon Underground. Mechanical
Engineering, Vol. 25, No. 2., February 2003,pp.
46-48.
The Engines of Our Ingenuity is
Copyright © 1988-2003 by John H.
Lienhard.
