TCS Daily


Black Hydrogen?

By Russell Seitz - May 1, 2003 12:00 AM

Coal is carbon, like charcoal or diamonds, right? Wrong - try to grill a steak over it and you'll notice there's more to it than meets the eye.

Coal is not a mineral, with a fixed chemical formula. It is a sedimentary rock rich in organic compounds of highly variable composition. It rarely contains as much as 90% of fixed carbon (indeed, such 'hard coals', or anthracites, make up a very small fraction of the coal trade).

Most coals are bituminous: "bitumen" is a biblical term for pitch or asphalt - a very heavy crude oil. Oil and gas are mixtures of hydrocarbons, some are hydrogen rich, and some are less so. For example, Methane is 80 molecular percent hydrogen, and liquefied natural gas is around 75%, while acetylene (C2H2) and benzene (C6H6) are 50% hydrogen.

Coal gets some of its energy of combustion from hydrogen, too. This is a fact that both carbon taxes and power plant emission permit prices should rationally reflect, since neither carbon content nor CO2 emissions potential can be gauged merely by the weight of coal used as fuel. Fuels, after all, get consumed one atom at a time.

A gram of hydrogen contains twelve times as many atoms as a gram of carbon. It follows that a coal containing 3% hydrogen by weight and, say, 72% carbon (the balance being oxygen, nitrogen, sulfur and ash), contains not one hydrogen atom per 24 carbon atoms, but one for every two. That's half the hydrogen to carbon ratio of liquid benzene or acetylene gas. Only a factor of 2 separates the heaviest fuel oils from some high volatile bituminous coals. Since both are derived from ancient plant remains, this is not too surprising.

This is not the way most analysts think about carbon dioxide sources - yet. Things may change as they realize that a one percentage point rise in the hydrogen content of coal used for America's electrical power would save far more in CO2 emissions than eliminating SUV's globally.

Environmentalists should take heart that there is enough good coal around to drive the bad out of circulation . Macroeconomic models of how coal quality arbitrage can minimize CO2 emissions are clearly worth developing, because coal is the only fossil fuel reserve so large that we can freely pick and choose from it. Apart from hydrogen, coal has another shock in store for those who demonize it - some contains less sulfur than crude oil.

A policy that promotes CO2 abatement by using the highest hydrogen coals fits into the operational philosophy of the school of international affairs analysis termed Realism, which contends that national interests - not competing political ideals within nations - should determine the course of policy. The Realists are well represented in Washington these days, and rethinking coal could widen the focus of their oil-centered analytical agenda. Hydrogen is central to the Bush administration's views on alternative energy - if using more hydrogen and less carbon is its goal, changing the diet of existing thermal power stations ranks beside raising their thermodynamic efficiency as the most sensible of policies.

'Dark Greens' may expect all the coal in China to go up in smoke, but the reality is that Beijing's view of technology policy is not so solitary, brutish, nasty or short. For all of China's lip service to Marx, her beau ideal is not Engels' dark satanic mills, but the gleaming nuclear plants that halted coal mining in France long before its reserves were exhausted.

It takes a committed pessimist to deny posterity's capacity to get nuclear, fusion, and renewable energy on line within the life span of bituminous coal reserves. Environmentalists should stop confusing anthrax and anthracite, and realize that hydrogen comes in all colors. Basic black is one with a bright future.

The author was a Visiting Scholar and Associate at the Harvard University Center for International Affairs, his work and commentary has appeared in Science, Nature, The New York Times, & The Wall Street Journal.
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