Energy by the numbers

The United States burns about 1 billion tons of coal a year. Most of it is used to generate electricity. The world’s total coal consumption is 5 billion tons. Although some coal goes from mine to power plant by barge, truck, etc., most coal transport is by coal train. A coal car is about 100 feet long and hauls about 100 tons. If all 5 billion annual tons were hauled by train, that train would go around the earth 40 times.

If coal were replaced by some renewable resource, such as switch grass, the energy density would be about one-fifth the energy density of coal. The switch-grass train would go around the Earth 200 times hauling the annual supply. All renewable energies pay a penalty for their lack of energy density. Wind, solar, biomass, etc. – an awful lot of that stuff is needed to accomplish very little.