"But among cities, few are as sustainable as Austin, Texas, which recycles its trash so assiduously that residents generated only 0.79 tons of garbage per household last year, down from 1.14 tons in 1992. Austin's city-owned electric company estimates that "renewable" power, mostly from west Texas wind farms, will account for 6 percent of its capacity this year, nearly doubling to 11 percent by 2008. Beginning in 2001, customers were allowed to purchase wind power at a price guaranteed for 10 years. But since it was more costly than conventional power, most people who signed up did so out of conviction—until last fall, when rising natural-gas prices meant that conventional customers were paying more, and suddenly the company was overwhelmed with new converts to sustainable power."