In this March 2005 file photo, students make their way across campus at Bates College in Lewiston, Maine. Credit: Pat Wellernbach | AP

Bates College in Lewiston said Thursday that it has achieved carbon neutrality, joining Bowdoin College, College of the Atlantic and Colby College.

The college said it had achieved a net zero footprint one year ahead of schedule.

From its baseline year in 2001, Bates reduced its campus carbon emissions by 95 percent and will account for its remaining footprint by purchasing carbon offsets, a college spokesperson said in a release. By buying carbon offsets, the college can essentially swap its surplus emissions with another entity that does not emit excess carbon via a trading company.

“Our mission statement calls for responsible stewardship of the wider world, and at this point in our history on this planet, there is no higher need than addressing climate change,” said Bates President Clayton Spencer. “More important, we have met this goal through shared effort, commitment and creativity by the entire college community with students leading the way.”

Out of some 700 U.S. colleges and universities to sign a carbon neutrality pledge in 2007, Bates is one of seven to date that have reached that goal.

Bates has worked on three fronts to shrink its carbon footprint. It reduced energy consumption through efficiency measures and strengthened the culture of sustainability on campus and changed behaviors.

The college also switched to renewable energy sources such as renewable fuel oil, a wood-derived liquid that is the primary fuel for its central heating plant.

Bates is the only U.S. educational institution using renewable fuel oil for heat, and one of only three U.S. institutions of any kind that heat with the fuel.

Citing its use of that fuel, the Association for the Advancement of Sustainability in Higher Education ranked Bates fourth in the world for its clean energy program in 2017.

Lori Valigra, investigative reporter for the environment, holds an M.S. in journalism from Boston University. She was a Knight journalism fellow at M.I.T. and has extensive international reporting experience...