For a moment, ignore all the environmental and climatic consequences of burning coal. Thought of only as an energy source, it is nonetheless demonstrably finite. Cambridge Professor (and Chief Scientific Adviser of the Department of Energy and Climate Change in the United Kingdom) David MacKay ran some of the math on the stuff:
In 2006, the coal consumption rate was 6.3 Gt per year. Comparing this with reserves of 1600 Gt of coal, people often say “there’s 250 years of coal left.” But if we assume “business as usual” implies a growing consumption, we get a different answer. If the growth rate of coal consumption were to continue at 2% per year (which gives a reasonable fit to the data from 1930 to 2000), then all the coal would be gone in 2096. If the growth rate is 3.4% per year (the growth rate over the last decade), the end of business-as-usual is coming before 2072. Not 250 years, but 60!
And, going back to climate change for a moment, we ought to remember that coal-fired power plants with carbon capture and storage equipment will use coal less efficiently to produce electricity. This is because some of the energy contains in the fuel will need to be dedicated to separating the carbon dioxide from the other flue gases (which, like air, are mostly nitrogen), then to pressurizing or liquefying the CO2, transporting it, and injecting it underground. It will also take energy to build the infrastructure necessary to perform these tasks.
Another thing to keep in mind is energy return on investment. Naturally, we started by exploiting the fossil fuel resources that were cheapest and easiest to extract: oil that literally shot up into the air when you sank a well. Now, we are in the world of difficult and expensive fossil fuels: those that take a lot of energy to get at and then process into usable fuels. We are certainly farther along when it comes to unconventional oil than when it comes to coal, but the same logic will eventually bite for the solid fuel. As such, the last portions of the global coal reserve will surely yield less energy for us than the first ones did, provided we don’t shift away from coal long before we get to those last reserves (which, because of climate change, we must).
As with all fossil fuels, coal has no long-term future. All of this is relevant because it illuminates the choice we are making. It’s not between a future that runs forever on coal (with climate change risks) and a future that runs on inexhaustible renewable forms of energy. It is between moving away from coal now, when it is still possible to save the climate, or doing so at the bitter end, once we have severely undermined the ability of the planet to support human life and prosperity. For everyone who isn’t the owner of a coal mine or a coal-fired power plant, this seems like a pretty easy choice.