Climate Science

August 1, 2010

Coal consumption: carbon dioxide and Earth's energy imbalance

There is a huge coal-burning plant in Lamar County, Ga., that produces a lot of electricity.

In order to do so it burns a lot of coal. Each and every day three coal trains arrive and each one is two miles long. This is described in Bill McKibben's new book "Eaarth" published in April 2010 (p187).

Now let's just do a little math.

Each rail car is about 50 feet long and has a capacity of about 120 tons each. This works out to about 105 coal cars per mile (5,280 feet) or 630 in a three-train day. This corresponds to about 75,600 tons of coal delivered, and consumed, a day. That is every day. One more calculation suggests that this one plant alone consumes about 27,594,000 tons per year. Now that is a mountain of coal.

If we connected together all these coal cars used in one year, it would stretch for 2,190 miles, or the distance from Plattsburgh to just short of Salt Lake City, Utah. Incidentally, according to the U.S. Energy Information Administration (EIA) website, in 2008 there were 599 coal-burning plants of varying sizes in the United States though none apparently as large as this one in Georgia.

When the carbon in coal from this one Georgia plant alone is burned, it combines with oxygen to form carbon dioxide gas with a total weight of over 100 million tons annually. And guess where this goes — yup, into the atmosphere. And this is only a tiny fraction of the total emissions that we produce.

Coal formation and consumption

Note that in the map (inset) of the coal fields of the United States, the EIA reports that over 1 billion short tons (1 short ton equals 2,000 pounds) of coal was mined, and burned, in 2009. Small amounts of this coal are exported but additional coal is also imported from Colombia, Venezuela and Indonesia. The United States coal was laid down long, long ago during four periods of the Earth's history when the planet was very, very warm and humid, and with carbon dioxide levels several times higher than today.

These periods are the Carboniferous from 280 million to 360 million years ago, the Triassic from 205 million to 245 million years ago, the Cretaceous from 70 million to 140 million years ago, and the Tertiary from 2 million to 7 million years ago. In just a few centuries we will return most of this fossil carbon, locked away for up to hundreds of millions of years, into the atmosphere.

Here is one more interesting fact that might bring these numbers closer to home. If we run one 100-watt light bulb continuously for one year it would require the combustion of 966 pounds of coal, or almost one half ton.

It takes a moment for numbers this big to register and settle in. At least they do for me. What they do show is the enormous nature of the problem that we face in the United States, and globally, as we try to grapple with how we can reduce our fossil fuel consumption as we follow our energy intensive lifestyle.

But why is this consumption and the resulting carbon dioxide emissions a problem? Let's take a closer look.

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