Coal In A Nice Shade of Green

To replace just America's surface transportation with cars and trucks running on fuel cells powered by hydrogen, America would have to produce 230,000 tons of the gas - or enough to fill 13,000 Hindenburg dirigibles - every day.

Published: 25-Mar-2005

ONG>After petroleum

 
When it comes to energy, we are trapped between a rock and several hard places. The world's soaring demand for oil is pushing against the limits of production, lifting the price of crude nearly 90 percent in the last 18 months.

Relief isn't likely to come anytime soon from drilling elsewhere: Oil companies spent $8 billion on exploration in 2003, but discovered only $4 billion of commercially useful oil.

Sadly, most alternatives to conventional oil can't give us the immense amount of energy we need without damaging our environment, jeopardizing our national security or bankrupting us. The obvious alternatives are other fossil fuels: natural gas and oil products derived from tar sands, oil shale and even coal. But natural gas supplies are tightening, at least in North America. And, of course, burning fossil fuels releases carbon dioxide, a greenhouse gas that may contribute to climate change.

As for energy sources not based on carbon, it would be enormously hard to meet a major percentage of America's energy needs at a reasonable cost, at least in the near term.

Take nuclear power - a source that produces no greenhouse emissions. To meet the expected growth in total American energy demand over the next 50 years would require building 1,200 new nuclear power plants in addition to the current 104 - or one plant every two weeks until 2050.

Solar power? To satisfy its current electricity demand using today's technology, the United States would need 10 billion square meters of photovoltaic panels; this would cost $5 trillion, or nearly half the country's annual gross domestic product.

Hydrogen? To replace just America's surface transportation with cars and trucks running on fuel cells powered by hydrogen, America would have to produce 230,000 tons of the gas - or enough to fill 13,000 Hindenburg dirigibles - every day.

For the near term, there is no silver bullet. So the important thing is to come up with so-called bridge technologies that can power our cities, factories and cars with fewer emissions than traditional fossil fuels while we move to clean energy like solar, wind and safe nuclear power.

A prime example of a bridge technology - one that exists right now - is gasification.

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.

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