America's Top 50 Green Cities

Want to see a model for successful and rapid environmental action? Check out our list of 50 leading green communities.

Case Study: Oakland's Zero Emission Bus

The East Bay cuts pollution with hydrogen-powered transit The buses are 40-foot-long behemoths, but they glide along downtown streets as silently as sleds coasting over snow; passersby barely turn their heads. The local AC Transit agency, which serves Oakland, Berkeley and other East Bay cities, hopes its fleet of three hydrogen-powered busesa€”the largest in the nationa€”will help to leave the environment just as undisturbed. Jaimie Levin, AC Transit's director of alternative-fuels policy, had his conversion experience in 1999 when he attended a demonstration. a€œI couldn't believe the potential for addressing environmental-health issues,a€ he says. a€œThe only emission from this bus was water vapor.a€ When the California Air Resources Board passed a regulation in 2000 requiring transit agencies to switch to cleaner buses, AC Transit had the impetus it needed to start a project. Over the next few years, it amassed more than $12 million in grants and forged partnerships with multiple companies that helped them design the hydrogen-powered buses. The first buses took to the streets in 2005, and the fleet should grow to eight in 2009. Although the buses substantially reduce transit pollution (diesel buses emit 130 tons of carbon dioxide per year), initiatives like AC Transit's remain largely showcase projects. Custom components drive the price of each bus to $2 million, more than five times the cost of diesel buses. Levin believes this will change if U.S. authorities throw their full political and financial weight behind hydrogena€”which seems a more feasible goal now that the Federal Transit Administration has started parceling out $49 million in research grants for fuel-cell buses. a€œUltimately, this becomes a public-policy decision,a€ he says. a€œWe can bring costs down by building the buses on a large scale, and local governments can help accelerate that.a€Graham Murdoch

Case Study: Make Power, Save the Heat

Chicago produces twice the energy with a third the carbon A typical fuel-burning power plant is wasteful in two ways: It produces harmful emissions, and it squanders two thirds of the energy it generates. The primary reason? Heat, the natural by-product of fuel combustion, dissipates into the atmosphere unused. Chicago is among the first cities to confront energy loss head-on. The city government has invested in cogeneration, the simultaneous production of heat and electricity, which is twice as efficient as conventional fuel-burning power production. The strategy is also a potent means of reducing greenhouse-gas emissions. A cogeneration plant produces only one third the CO2 of a coal-fired power plant. In its most recent energy plan, Chicago committed to producing 1.5 billion kilowatt-hours of electricity from cogeneration by 2010a€”25 percent of the city's increased energy needs from 2000 to 2010. Rather than allowing accumulated heat to escape through exhaust vents, a cogeneration facility collects the hot steam exhaust produced by natural gas combustion and channels it into a network of pipes that distributes it throughout the building. a€œYou can take steam and use it directly for heating the building, cooking, and hot water,a€ says John Kelly of Illinois-based Endurant Energy. a€œThat's huge.a€ Chicago's famed Museum of Science and Industry developed a cogeneration plant in 2003, and in recent years other city institutions, such as the Jesse Brown VA Medical Center, have followed suit. Kelly thinks the cogeneration meme will soon spread. a€œManhattan is anticipating a power shortfall of 1,000 megawatts,a€ he points out. a€œIt's a perfect candidate.a€ HOW IT WORKS Cogeneration starts when a generator burns natural gas [A] to produce electricity. The hot exhaust from that combustion boils water [B], and that steam powers a turbine [C] connected to a second generator [D], producing another shot of electricity. Any leftover waste steam heats the building.Graham Murdoch

Case Study: Sunroofs in Fog City

San Francisco turns wasted roof space into power Travelers flying over San Francisco's Moscone convention center could easily mistake the roof for a parking lot. But the 60,000-square-foot expanse of black atop the building isn't asphalta€”it's an intricate honeycomb of photovoltaic cells. When San Francisco's Public Utilities Commission teamed up with PowerLight Corporation to cover the convention center's roof in solar panels, some observers scoffed. a€œThe tongue-in-cheek remarks were, a€˜Oh, Fog City,' a€ says Susan DeVico, then a spokeswoman for PowerLight. a€œBut photovoltaic doesn't need to have strong sun.a€ The installation has defied critics since its unveiling in 2004, delivering enough juice to supply the Moscone Center during events, and more than 180 homes when the center is dark. The solar cells that stud the roof contain silicon semiconductors that absorb photons from sunlight, setting a procession of electrons in motion to create a current. Now the city is staking its renewable future on letting the sun in. Moscone is just the first stepa€”officials are blanketing the city with solar cells, installing solar arrays on municipal buildings, including ports and libraries, and a $2.2-million solar rooftop on a wastewater-treatment facility.Kris Holland

Case Study: Tapping Geysers for Watts

Free steam outside Santa Rosa creates 850 megawatts of power Most people associate geothermal energy with countries like Iceland, where the thin crust creates lakes the temperature of hot tubs. But the U.S. actually harvests more electricity from the earth's natural heat than any other nationa€”and the simmering underground steam reservoir called the Geysers, in the redwood-studded wilderness outside Santa Rosa, is the world's largest such geothermal installation. For every Vesuvius that erupts on our planet, far more magma remains underground, heating pockets of water and yielding vast amounts of steam. Mining these veins of vapor is a€œjust like drilling for oil or gas,a€ says Dennis Gilles, a senior vice president of Calpine, the company that owns and manages 19 of the 22 power plants at the Geysers. a€œBut you're sending the drill down into a reservoir of hot steam instead.a€ At the Geysers, pipes send the steam from the drilled wells to central collection facilities, where it is used to power 31 steam turbines. The system generates more than 850 megawatts of electricity, enough to power about 850,000 homes on the California grid. Santa Rosa's relationship with the Geysers dates to the 1920s, when entrepreneurs installed enough steam piping and turbines to light the buildings of a nearby resort. By the 1990s, however, as the plumes of steam thinned, it was clear that after many years of use, the famed steam fields were almost tapped out. In 1998, the city approved a plan to replenish the Geysers. A $187-million municipal initiative funded the construction of a four-foot-wide, 41-mile-long pipeline that routes 12 million gallons of the city's wastewater per day back to the steam fields. Since the pipeline's inauguration in 2004, it has consistently boosted the Geysers's electrical output by about 85 megawatts, replacing conventional processes that would have released 570 million pounds of carbon dioxide into the atmosphere every year.Kris Holland

Case Study: Heating Homes from Waste

Salt Lake City saves eight tons of carbon dioxide with the warmth of sewage When Salt Lake City attorneys Jon and Phillip Lear decided to set up offices in the Major George Downey mansion downtown in 2005, gas prices had spiked after Hurricane Katrina, and they started brainstorming alternative heating and cooling systems. a€œAlternativea€ is the word for what the brothers came up with. The system they designed, with help from engineers at Utah's Sound Geothermal Corporation, pulls heat from warm sewage water. A secondary network of pipes surrounding a sewage pipe carries a water-based glycol that enables a heat exchangea€”since it is cool relative to the sewage water, it rapidly absorbs heat. The pipes carry the warmed glycol back into the house, where the accumulated heat energy radiates from vents. On hot summer days, the glycol absorbs heat from inside the house and releases it underground. The entire setup uses about 40 percent less energy than a conventional heating and cooling system would, reducing carbon dioxide emissions by eight tons a year. The Lears moved their offices there permanently in January. Public-utilities director Jeff Niermeyer hopes to install similar systems in other public buildings within the next few years. a€œWith any wastewater system, there's a lot of heat that you've already put in for other purposes,a€ he says.Graham Murdoch

Case Study: Turning the Tides into Electricity

New York City hopes to generate enough power for 8,000 homes with underwater turbines Traditionally, New Yorkers have considered the East Rivera€”alongside pigeons and trasha€”an indelible part of the landscape, better off overlooked. But the city and state have partnered with Verdant Power to install a fleet of submerged turbines near Roosevelt Island, a few hundred feet east of Manhattan, that will transform the river into a valuable power source. New York is already one of the world's most energy-efficient citiesa€”an average New Yorker uses about half the electricity an average San Franciscan does. Yet an anticipated influx of new residents will further strain existing energy sources, so city and state officials gave Verdant about $3 million to harness power from the river's strong tidal currents. Verdant's turbines resemble their wind-farm cousins, with triple-bladed rotors that generate electricity from kinetic energy. The East River's tides turn the rotors only about once every two seconds. But since water currents are about 1,000 times as dense as wind currents, each turbine sends up to 36 kilowatts into the Roosevelt Island grid. When all 300 planned turbines are installeda€”in the next decade, if all goes as planneda€”the underwater field will produce 10 megawatts of power, enough electricity for 8,000 homes. But hydropower is tricky. During initial tests last summer, tides were 20 percent more powerful than anticipated, and the currents simply snapped the blades off the turbines. Verdant says it can solve the problem with reinforced turbines; the replacements should be ready for East River testing this year. The company is also in talks to install similar systems in the St. Lawrence River in Ontario and in Seattle's Puget Sound.Graham Murdoch