Coal in a nice shade of green

Thomas Homer-Dixon and S. Julio Friedmann suggest using a new-type energy source known as gasification. What is it?

Here’s how it works: In a type of power plant called an integrated gasification combined-cycle facility, we change any fossil fuel, including coal, into a superhot gas that is rich in hydrogen – and in the process strip out pollutants like sulfur and mercury. As in a traditional combustion power plant, the heat generates large amounts of electricity; but in this case, the gas byproducts can be pure streams of hydrogen and carbon dioxide.

This matters for several reasons. The hydrogen produced could be used as a transportation fuel. Equally important, the harmful carbon dioxide waste is in a form that can be pumped deep underground and stored, theoretically for millions of years, in old oil and gas fields or saline aquifers. This process is called geologic storage, or carbon sequestration, and recent field demonstrations in Canada and Norway have shown it can work and work safely.

The marriage of gasified coal plants and geologic storage could allow us to build power plants that produce vast amounts of energy with virtually no carbon dioxide emissions in the air. Moreover, these plants are very flexible: Although coal is the most obvious fuel source, they could burn almost any organic material, including waste cornhusks and woodchips.

There are hurdles. For example, we need a crash program of research to find out which geological formations best lock up the carbon dioxide for the longest time.

On balance, though, this combination of technologies is probably among the best ways to provide the energy needed by modern societies – including populous, energy-hungry and coal-rich societies like China and India – without wrecking the global climate. The combination of gasified coal plants and geologic storage can be our bridge to the clean energy of the 22nd century and beyond.