The University of New Hampshire has celebrated its efforts to be green by using gas from a landfill to power the loudspeakers at its commencement and turning leftover food from the ceremony into compost.

The university is the first in the nation to receive most of its heat and electricity from landfill gas. It showcased the achievement at the eco-themed graduation ceremony Saturday.

The keynote speaker was the CEO of Londonderry-based Stonyfield Farm, which uses all natural and organic ingredients to make yogurts and smoothies.

CEO Gary Hirshberg is outspoken on sustainability issues. He urged the 2,200 graduates to be determined and to take risks.

He says the future facing most of them is the one he faced when he started in business 26 years ago: broke, clueless about the future and in debt.