Originally published on 6/28/10
Many energy experts contend natural gas is the ideal fuel as the world makes the transition to renewable energy. But since much of that gas will come from underground shale, potentially at high environmental cost, it would be far better to skip the natural gas phase and move straight to massive deployment of solar and wind power.
by Daniel B. Botkin
For several years, many voices, including Texas energy baron T. Boone Pickens, have been touting natural gas as the best energy source to form a bridge between the current fossil-fuel economy and a renewable energy future. Proponents contend that not only is natural gas a cleaner-burning fuel than coal, producing lower greenhouse gas emissions, but that reserves of natural gas are far greater than previously believed because of vast reserves trapped throughout the U.S — and around the world — in huge underground formations of shale.
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But what is the reality behind the optimistic claims for shale gas? The U.S. Geological Survey lists natural gas “reserves” — the amount believed to be in the ground — in four categories: readily available with current technologies, which accounts for only 1 percent of the known natural gas in U.S. territorial limits; technically recoverable (5 percent); marginal targets for accelerated technology (6 percent); and unknown but probable (84 percent). Shale gas shares the fourth category with coal gas and methyl hydrates. The latter are a kind of water ice with methane embedded in it and occur only where it is very cold, in Arctic permafrost and below 3,000 feet in the oceans.
In researching how best to make the transition to the green energy future, one of the first calculations I made was to find out how long the natural gas in each of the four categories would last if we obtained it independently — that is, only from U.S. territory. I was shocked by the result: Just using our 2006 rates of use of natural gas consumption — not including any major transition to fueling our cars and trucks — the “readily available” gas within the United States would be exhausted in just one year. That, plus what is called “technically recoverable” gas, would be gone in less than a decade. What is termed “unknown but probable” would last about a century.
This means that any significant increase in our consumption of natural gas will have to come from the “unknown but probable” reserves, much of which will be from formations of shale, a sedimentary rock formed from muds in which bacteria released methane. Most of this gas is so deep underground or otherwise not very accessible that nobody is really sure that we can get at a lot of it, or of how high an environmental price we must pay to retrieve it.
Read entire piece at e360.yale.edu