The U.S.'s natural-gas resource base, including proved reserves, stood at 1,205 trillion cubic feet (Tcf) at the end of 1998 and is expanding, indicates the biennial report of the Potential Gas Committee, a volunteer organization of 165 geologists and engineers from the gas industry, government, and academia. At current levels of production, that means the U.S. has about a 63-year supply of the clean-burning fuel, which is seen as a "bridge" between the oil-dominated energy-consumption pattern of today and tomorrow's reliance on alternative fuels. The committee's estimate of the resource base is 2.8% higher than it was in 1990. "The 1998 assessment reaffirms the committee's evaluation of an abundant natural-gas resource potential," comments John B. Curtis, director of the Potential Gas Agency at the Colorado School of Mines, Golden, Colo., which provides technical assistance to the estimate. Adds Chris McGill, director of gas supply and transportation for the American Gas Assn., the Washington, D.C.-based trade group of gas utilities: "Despite a 35% increase in natural-gas consumption since the mid-1980s, advances in new exploration technologies have helped to open new sources to development. We in the natural-gas utility business view these figures as a testament to the sustainability of future natural-gas production at even greater annual rates, in line with current projections of consumption reaching nearly 30Tcf for 2010."