The December 21, 2010 announcement that San Francisco's polluting Potrero Power Plant would shut down by the end of the year was as much a cause for celebration as it was a reason to recount the twists and turns that it took to finally shutter the city's last fossil fuel-burning commercial power plant. For many years, the preferred method of closing Potrero was to build three new power plants to replace it smack dab between the Bayview-Hunters Point and Potrero Hill communities where San Francisco's dirty power plants have been located for over a century. The environmental, social justice, and sustainability advocacy required to flip the switch on Potrero is certainly a lesson in the heavy lifting that any city must undertake in seeking to end its reliance on fossil fuel power plants.

The Potrero Power Plant itself was built in 1965, but its location has been a site of electricity generation since 1890. Consisting of a massive gas boiler and diesel peaking units that operated when the boiler came down for maintenance, Potrero has been blamed for environmental health disparities in Southeast San Francisco and negative impacts on the bay due to the discharge of heated water used to cool the facility. City Attorney Dennis Herrera is a neighbor of the power plant and made its closure a priority since he was first elected in 2001, while former district Supervisor Sophie Maxwell fought perhaps even longer before watching the plant shut down in the waning days of her last term in office.

Yet it is the unique coalition of organizations, activists, and elected officials that moved the City to abandon its plan to spend $270 million on new gas power plants to replace Potrero that is perhaps the most fascinating part of the recently-concluded power plant saga. Groups such as the Potrero Boosters and SF Community Power had fought for the better part of a decade to close the Potrero Plant but were told time and again that new combustion turbine power plants were required if Potrero was ever to shut down. At a July 2007 hearing of the San Francisco Public Utilities Commission, longtime Bayview-Hunters Point activist Espanola Jackson was the lone community voice of dissent against a vote to greenlight the construction of the first power plants to be built in the City in decades.

Within a short period of months, Ms. Jackson's empassioned plea for an end to power plants in her disproportionately polluted corner of San Francisco would attract the support of environmentalists within the Sierra Club and Green Party, community organizations such as the A. Philip Randolph Institute and Greenaction, and the newly-founded civil rights non-profit Brightline Defense Project. In late 2007, Public Utilities Commissioner David Hochschild called the question of whether or not to build new power plants "the biggest energy decision facing San Francisco since construction of the Hetch Hetchy Dam."

It was an early 2008 memorandum from San Francisco Planning and Urban Research, however, that blew the doors wide open on the power plant debate. The "SPUR memo" made the case based on hard facts that estimates of the amount of electricity required to keep the lights on in San Francisco had been wildly overstated and that Potrero could be shut down upon completion of an underwater cable from the East Bay without subjecting the lungs of Ms. Jackson and her southeast San Francisco neighbors to at least thirty more years of power plant pollution. Environmental justice and community advocates were now armed with factual analysis to galvanize support at the San Francisco Board of Supervisors, and that summer an unlikely dynamic duo of Michela Alioto-Pier and Ross Mirkarimi manhandled a trio of power plant hail marys that were lobbed at the Board by those who believed it impossible to close Potrero without continuing its power plant legacy.

By the fall, the anti-power plant coalition gained a powerful ally in Mayor Gavin Newsom, whose green credentials depended on his ability to successfully navigate toward a pollution-free solution to the Potrero Power Plant. In late 2008, Public Utilities Commissioner Dick Sklar, who has since passed away, made a successful motion to tear up the contract to build new power plants in order to make a continued case for closure of Potrero outright. Over the next year, Supervisor Alioto-Pier in particular was dogged in her insistence that San Francisco keep pressure on the California Independent System Operator, a state agency charged with maintaining as much electricity as possible to guard against remote instances of power failure. Growing solidarity among the San Francisco city family in 2009 was complemented by constant community delegations to Independent System Operator meetings in which advocates sometimes ended up in shouting matches with power plant regulators, and Public Utilities General Manager Ed Harrington helped shepherd the sale of the combustion turbines once slated to pollute San Franciscans in order to help the City close a massive budget deficit.

The year 2010 began with the anticipation that the pending completion of the 400 megawatt Trans Bay Cable would at last trigger the demise of the Potrero Power Plant. Expectations dipped, however, when most of 2010 was spent fixing a series of faulty computer chips at the Trans Bay Cable sub-station in San Francisco. The months leading up to December left many advocates who had fought to close Potrero with a feeling of both powerlessness, based on the fact that fate now rested in the hands of electrical engineers scrambling to replace malfunctioning motherboards, and a sense of reflection, based on the long road that preceded the path to a power plant-free city. That time of uneasiness allowed San Francisco's power plant battle to be placed into context, however, with a determination that the closure of Potrero would not require the construction of new power plants elsewhere and a realization that the main challenge facing cities aiming to phase out fossil fuel generation is that dirty electricity is simply too safe and predictable in the technocratic eyes of regulators.

Few sustainability experts will dispute that we as a society must wean ourselves off of reliance on fossil fuel power, especially in cases such as that of San Francisco, where the hard work of so many was required to responsibly and dispositively demonstrate that the Potrero Power Plant was obsolete not only in terms of powering San Francisco but in guarding against unforeseen contingencies. The Potrero Power Plant is no longer, but California currently operates over 900 power plants that collectively produce much more electricity that the state needs even on the year's hottest summer days. Maybe now is the time for San Francisco to use its lessons learned to help shut down some of those old dinosaurs.

Joshua Arce is the Executive Director of the Brightline Defense Project.