Middlebury College is working hard to integrate sustainability into all facets of its academics, operations, and planning. The College composts and recycles sixty percent of its waste, has LEED certification requirements for all new buildings, is conserving 2,100 acres of land in perpetuity, and will have 30% real food (that which is local, humanely raised, ecologically grown, and/or fair trade) in its dining halls by 2016. Capping this list of impressive sustainability measures is the university’s commitment to carbon neutrality by 2016.
Biomass gasification is an important part of Middlebury’s carbon neutrality plan. Biomass energy is derived from plant sources, and is sustainable as long as demand does not outstrip the natural growth rate of those plants. To ensure biomass sustainability, Middlebury has planted a forest of fast-growing, perennial willow trees to provide the wood chips for the campus biomass gasification plant.
The biomass gasification plant will cut the college’s carbon dioxide output by 40 percent; reduce their use of fuel oil by 50 percent; and will stimulate a local, renewable, economy. Within twelve years the plant will have paid for itself; the plant will also save the College almost a million dollars a year in fuel costs, with a savings increase of 3% per year. Equally important, Middlebury’s commitment to carbon neutrality is an important example to higher education. This university has shown that there are many different paths to sustainability, and that carbon neutrality is both fiscally sound and achievable.
Middlebury’s biomass gasification plant connects climate, energy, and community for a more sustainable energy future. For almost a decade, carbon reduction has been a community driven initiative at the College, and in 2007 Middlebury set a goal of achieving carbon neutrality by 2016. The completion of the biomass gasification facility marks a significant milestone toward that goal. Students, staff, and faculty from many different departments across campus were involved at every stage of this project.
How Biomass Gasification Works
Biomass gasification is much more complex and efficient than a household wood stove. Wood chips are superheated in a low oxygen chamber where they smolder and emit wood-gas. Oxygen is then introduced on the backside of the boiler causing the gas to ignite, producing heat (at temperatures of over 1100° F) to make steam that is distributed throughout campus for heating, cooling, hot water and cooking.
Exhaust from this process circulates through a cyclone separator, forcing larger particles to drop out. The exhaust then enters the bag house where it passes through a series of filters to remove fine particulate matter. The filtration system in Middlebury’s biomass plant is rated to remove 99.7 percent of particulates, so most of what one sees coming from the smoke stack is water vapor.