Carbon Countdown: The Million Gallon Question

The “million gallon question,” or more accurately, the “640,000 gallon question,” is one of the most significant obstacles in the College’s quest for carbon neutrality by 2016. According to the Climate Action Plan adopted in 2008, 89 percent of the College’s greenhouse gas emissions comes from heating and cooling buildings using a steam-based system. Although the opening of the biomass plant in 2009 reduced the College’s annual consumption of  no. 6 fuel oil by roughly 1,350,000 gallons, there still remains 640,000 gallons per year required to meet the College’s heating and cooling needs. Given that this Vermont winter is unlikely to be significantly milder than last year’s (climate change doesn’t happen on that kind of time-scale), how can we either reduce or replace the emissions from burning all this oil?

In order to address this “640,000 gallon question,” the College identified two potential solutions in 2008: the construction of an additional biomass facility, and the use of biodiesel in place of fuel oil to generate steam.

An economic, environmental and social analysis of these two options revealed the construction of a new biomass plant as the better path. Economically, the CAP identified biomass as more affordable given the high cost of production of biodiesel. Biodiesel could also pose an environmental problem because greenhouse gases emitted during the production of the fuel (from fertilizers, irrigation and transport) might exceed those absorbed from plant growth. Furthermore, the growth of corn for biodiesel contributes to deforestation and rising global food prices.

However, a complete switch from fuel oil to biomass also has its own problems. A new biomass plant would be expensive. Energy generated using biomass also takes more time to come online and take offline compared to fuel oil. This makes it difficult to respond to changing demand for steam. Another issue was sustainably sourcing all the woodchips needed to replace 640,000 gallons of fuel oil. The College would also need to account for the greenhouse emissions of transporting the woodchips.

Then in 2010, a far better option was identified: bio-methane produced from cow manure. Originally, the gas would have to be produced offsite by manure digesters on local farms, trucked to a facility near campus, then piped underground to the central heating plant. The use of bio-methane to meet heating and cooling needs has many positive implications for the College’s environmental impact. Methane, or natural gas, has the highest ratio of energy to carbon dioxide output of any fossil fuel because it has the highest density of hydrogen-carbon bonds. In comparison to other fuel oils, combustion of methane releases about 25 percent less carbon dioxide. In addition, the purified gas contains fewer impurities, such as sulfur and nitrogen, than fuel oil, so burning it produces fewer pollutants.

With the construction of the VT Gas pipeline, the College will be able to pump bio-methane (which is chemically equivalent to natural gas) into the pipeline. The biomass plant would be connected to the larger VT gas pipeline, rather than a direct pipeline running from the farm’s digester. So while the biomass plant might not necessarily be burning all bio-methane all the time, the College would be paying VT Gas for all the natural gas it uses as if it were bio-methane. VT Gas would then pay the dairy farms for their bio-methane contribution.

However, the construction of the VT Gas pipeline is still controversial. It will be transporting fracked gas from Canadian tarsands. Fracking also has noticeable environmental impacts on water quality. Despite the controversy of the pipeline, its construction will have an immediate impact on the College’s goal of carbon neutrality by serving as transport infrastructure for the biomass plant.