On the face of it, silver-heeled Aspen and salt-of-the-earth Greensburg, Kansas, would seem to have virtually nothing in common. For starters, few people travel to Greensburg for leisure. Located in pancake-flat south-central Kansas, the town of 1,300 was almost completely leveled by a tornado in 2007. But when it began rebuilding, it sought to become one of the most sustainable municipalities on the planet.

As part of that transformation, Greensburg in 2008 began drawing its electricity from a bank of ten new wind turbines located four miles away. Oil and gas production remains a staple of the local economy, says Mayor Bob Dixson, but the wind that ruffles the fields of alfalfa, corn, and soybeans is free—and averages seventeen m.p.h., enough to help the local electric utility become 100 percent renewable.

Hence the connection to Aspen, whose Aspen Electric in August joined the municipal electric utilities of Greensburg and Burlington, Vermont, to become only the third utility of its kind to achieve 100 percent renewable power. Perhaps more notable, in this enclave of philanthropy and wealth, has been the cost: Aspen Electric went the full green monty without jacking up rates. The utility’s customers have among the lowest residential rates in Colorado, a state whose average rate of 12.47 cents per kilowatt-hour during August 2015 lagged the national average of 12.93 cents, according to the U.S. Energy Information Administration.

The bottom-line message from this trio of municipal utilities is that achieving 100 percent renewable portfolios is not as pie-in-the-sky as some might think. Other municipalities in Texas, Colorado, and especially California—including much bigger ones—have adopted similar goals.

Aspen Electric got there by starting early to develop local resources. Driven by a desire for energy security, the city government in the 1980s committed $4.5 million to retrofit the nearby federal Ruedi dam with five megawatts of generating capacity. The city utility in the early 1990s invested in another hydro project on Maroon Creek, just outside of town, in addition to buying power from Colorado River Basin dams. About half of the utility’s electricity now comes from hydro—including, for the first time last winter, the Ridgway dam in west-central Colorado. As long as snow and rain fall, once the capital investment has been paid off, the electricity becomes crazy cheap.

“It’s important to acknowledge what your comparative advantage is in terms of renewable energy in your area,” says Will Dolan, the former renewable energy manager for Aspen Electric. “It could be landfill gas, it could be biomass, it could be geothermal.”

In addition, at about the time Aspen adopted the Canary Initiative—the city’s ambitious greenhouse gas–reduction goal—in 2005, it began buying power from wind turbines in Nebraska and South Dakota. Now wind is the source of 53 percent of the utility’s power. The final 1 percent of Aspen’s portfolio comes from electricity created by burning methane from an Iowa landfill. (For the record, Aspen Electric’s six thousand customers represent only about half of the municipality and don’t include the four local ski areas. For reasons too complex to explain here, the other half of Aspen’s energy consumers are served by Holy Cross Energy.)

Burlington, a classic New England city of 42,000 whose downtown is watched over by the white spire of the Unitarian church, offers another example of how going renewable can be frugal and practical.

“The common wisdom of renewable power is that it will cost customers a lot,” says Neale Lunderville, general manager of the municipal utility. “But we serve 100 percent of our power from renewable generation, and we have not raised our rates since 2009—nor do we anticipate raising our rates anytime in the near future. And we accomplished this through very standard financing and power-purchase types of agreements.”

Critics can find fault with these communities’ electrical portfolios, and they have. Some have questioned the use of biomass by Burlington Electric. Aspen’s power comes partly from giant dams that have drowned Glen Canyon and other treasured chasms of the West. And some electricity in each of these towns is ultimately traceable to coal or gas. That’s true even when the utility pays for transmission, called wheeling, such as Aspen does for use of high-voltage lines from Nebraska.

Aspen, Burlington, and Greensburg all also employ a financial device called renewable energy credits, which allows utilities to claim environmental attributes of the energy generation without having the electrons themselves. Using this financial device, Palo Alto, California also claimed carbon neutrality in its electrical supply beginning in 2013. Seattle City Light achieved carbon neutrality even earlier, in 2005, and now secures 94 percent of its electricity from hydro, wind, and landfills for its more than 750,000 residential
consumers.

And of course, Aspen has had bumps in its road toward 100 percent renewables. City officials thought they had a green light from the local citizenry to re-create a hydroelectric plant on Castle Creek that had served the city from 1885 to 1962. Some 70 percent of voters approved the bond issue in November 2007. Then, things went south—and after an ensuing 2012 vote, Aspen has a $2 million turbine sitting in cold storage.

While some bad feelings remain, Aspen’s road-to-renewables story resonates as a positive one. At the American Renewable Energy Day conference in August, Aspen Mayor Steve Skadron announced that having achieved 100 percent renewables, the city now wants to confront transportation, which accounts for 19 percent of the city’s total emissions.

It’s a significant challenge for any community, even those whose energy consumers don't arrive in private jets. But give yourself credit, Aspen: you set out to achieve a goal, and you succeeded. And hooray for that.