BAR HARBOR - College of the Atlantic has become the nation's first "net-zero" campus for carbon emissions, school officials said Wednesday.

The college said it has offset its entire emissions output of 2,488 tons over the past 15 months by investing in a greenhouse gas reduction project in Oregon.

At his inauguration in October 2006, College of the Atlantic President David Hales pledged to make the campus carbon-neutral by this month. Since then, more than 450 other universities and colleges have also taken "net-zero" pledges through the American College and University Presidents Climate Commitment program.

"We have much more to do to directly reduce our emissions, but it is satisfying to know that the last 15 months of College of the Atlantic's contribution to the increase of greenhouse gases in our atmosphere adds up to zero," Hales said.

College of the Atlantic has about 300 students and offers only one major, human ecology, which studies the relationship between humans and their environment.

The college has undertaken a number of steps to reduce its greenhouse gas emissions. Last month, it began buying all its electricity through a hydroelectric generator, which will reduce its carbon emissions by 22 percent next year.

The college also has begun improving the energy efficiency of its buildings. Where possible, it has replaced fluorescent light bulbs and encouraged car pools, bicycling and flexible work schedules so that some employees can work at home.

To become carbon neutral, the college is buying carbon offsets for about $25,000 through The Climate Trust of Oregon. Carbon offsets aim to mitigate greenhouse gas emissions by investing in carbon-reduction programs to offset emissions generated elsewhere.