Now that the big climate conference in Bali is over, questions are arising about how (or whether) the U.S. and other countries can reduce their CO2 emissions. Meanwhile, the U.S. presidential race has gone into full swing. As it garners more attention, so do the energy platforms of the various candidates, who are all being scrutinized over how their energy views square with the greenhouse gas issue.

Remarkably, through the blizzard of speeches, talking points, and recriminations about whose plan has the most potential (and of course, recriminations about the U.S.), two of the most promising trends in global energy use have gone largely unnoticed: the ongoing decarbonization of the world’s fuel supply and the growing role that natural gas is playing in that mix.

Although many pundits talk about peak oil, there’s not much talk about “peak gas.” That’s because there continues to be a surfeit of gas, and more gas is being discovered all the time. Between 1995 and 2005, global proved natural gas reserves increased 25 percent, to some 6,348 trillion cubic feet. At current rates of extraction and assuming no new discoveries, that’s enough gas to supply the world for another six decades. But better still, new gas reserves are being discovered faster than new oil reserves.

This is good news regardless of your positions on peak oil or global warming. Gas is the cleanest of the fossil fuels. It emits about half as much carbon dioxide as coal and creates far fewer air pollutants. Plus, it’s cheaper than oil (on a Btu basis) and it’s abundant. Despite those facts, environmental groups and presidential candidates rarely (if ever) tout gas as a way to reduce carbon dioxide emissions or imports of foreign oil.

The decarbonization of the world’s energy mix has been ongoing for about two centuries. From pre-history through the 1700s and early 1800s, wood was the world’s most common fuel. Wood has a carbon-to-hydrogen ratio (C:H) of 10 to 1. That is, wood has about 10 carbon atoms for every hydrogen atom. But as the Western world industrialized, wood lost its dominance to coal. Coal was a dramatic improvement over wood because it is a far denser source of energy, with a C:H ratio of about 2 to 1. But coal was destined to lose out to oil as the fuel of choice, particularly for transportation, because of oil’s superior energy density, a product of its 1 to 2 C:H ratio. Over the coming decades natural gas (CH4) consumption will increase, thanks to its 1 to 4 C:H ratio.

This decarbonization occurs because energy consumers always seek cleaner, ever-denser forms of energy to allow them to do ever more work with ever more precision. (Lasers are a prime example of this trend toward super-concentrated energy forms.) Jesse Ausubel, director of Rockefeller University’s program for the human environment in New York City, said that although the trend toward decarbonization may waver for a decade or two as countries like India and China add new coal-fired power plants, “over the long term H gains in the mix at the expense of C, like cars replacing horses, color TV substituting for black-and-white, or e-mail gaining the market over hard copies sent through the post office.” (For more on Ausubel, see ET, September 2007.)

Consumers’ preference for ever-greater energy densities can be seen by looking at the world’s insatiable appetite for electricity, a super-dense form that can be used for a myriad of purposes. And one of the best fuels for electricity production is natural gas.

Although governmental action hasn’t had much to do with the decarbonization trend, it could be doing more to encourage it. So why isn’t that part of the current energy discussion? Rather than embrace a technology that’s available and relatively cheap, and promote gas – particularly for use in the automotive sector – Congress and the presidential candidates are spouting nonsense about ethanol (and ethanol-fueled cars).

Wood dominated the global energy scene through the 18th century, coal dominated the 19th century, and oil dominated the 20th century. With any luck, natural gas will be the dominant fuel of the 21st century. Just don’t expect to hear about it from Al Gore or the presidential candidates.