Arlington County reached a milestone in its efforts to cut greenhouse gas emissions: 100% of county government operations are now powered by renewable electricity.

This means county government offices, streetlights, traffic signals, water pumps, and wastewater treatment facilities are now running on clean electricity. Arlington achieved this two years ahead of its 2025 goal.

Most of that electricity – some 80% – is coming from a sprawling solar farm in rural Pittsylvania County, Va. The facility covers 1,500 acres of what used to be crop land, producing 120 megawatts of power. That’s enough to power roughly 30,000 homes.

Arlington County is purchasing about one-third of the power generated at the solar farm, while Amazon is buying the rest.

Buying clean energy is not costing the county more money than buying power generated from fossil-fuels, says Demetra McBride, bureau chief of Arlington’s Office of Sustainability and Environmental Management.

“We’re actually gaining revenue now on our renewable electricity,” McBride says. The county entered into the power purchase agreement three years ago, locking in a fixed rate to buy the solar energy. Since then, standard electricity rates have spiked, meaning Arlington is paying less than it otherwise would, because of its solar agreement.

Powering government operations with clean energy is part of the county’s Community Energy Plan, which aims to make Arlington carbon neutral by 2050.

Arlington is not the first jurisdiction in the region to power government buildings with renewable energy. Montgomery County made government facilities carbon neutral as of 2016, buying clean electricity from wind farms. In D.C., government buildings run on clean electricity through power purchase agreements and the purchase of renewable energy credits. Other jurisdictions may take similar steps soon; climate plans in both Fairfax County and Prince George’s County call for powering county buildings with renewables.