New System Paves the Way for Decarbonization at College

Continued from page 8 generation totals 9,233 megawatt-hours per year (MWh/yr), emitting greenhouse gases equal to over 15,000 metric tons of carbon dioxide (c). However, all that only amounts to about 40 percent of the college’s energy demand. To cover the campus’ remaining energy needs, the college purchases electricity from a local provider, Eversource.

Emissions from this purchased electricity make up our “Scope 2” emissions. Our purchase of electricity from Eversource provides us with 11,786 MWh/yr, and the highest percentage (34.14 percent) of EverSource’s system power comes from natural gas. According to data from 2015, our purchase at the time from Eversource meant that our purchased electricity emitted the equivalent of 4,000 metric tons of carbon dioxide. All told, the college emitted greenhouse gases in 2015 equal to the release of almost 20,000 metric tons of carbon dioxide.

Acknowledging a Need for Change

In 2015, this alarming number gave rise to a new group on campus to try and assess how we could manage our large carbon footprint.

At that time, the college formed a Climate Action Task Force. The original members of the Climate Action Task Force included the former director of sustainability, chief of campus operations, director of facilities, chief student affairs officers, the chief financial office chair, and various professors from the geology and environmental studies departments who all helped craft a “carbon management hierarchy” approach.

The Climate Action Task Force set forth some propositions for how the college could most efficiently become carbon neutral. They brainstormed with an energy consulting firm, Competitive Energy Services, to reduce carbon emissions by almost 12,000 metric tons by 2034. They discovered that this reduction could only be achieved with new infrastructure, regional improvements to the electrical grid via Eversource, and various other conditions that would require mass changes. In determining the feasibility of these mass changes, the group looked at Smith College, and instead of focusing on small projects to reduce emissions, Amherst committed to a total overhaul of the major source of its Scope 1 emissions: the natural gas-powered cogeneration system.

To tackle the carbon emissions from the natural gas-powered cogeneration system, the college worked with another sustainable engineering firm, Integral Group, to form a report on Amherst College’s energy profile. In 2019, Integral found that the college’s natural gas-powered cogeneration system had been deteriorating in efficiency over the years, with more than 4,000 lbs/hr, or 10 percent, of steam being lost before reaching the campus distribution network.

The decision to rework Scope 1 emissions also came with some immediate action to address the college’s carbon emissions from offsite electricity generation — its Scope 2 emissions. In 2019, the year of Integral Group’s report, the college participated in a Power Purchase Agreement (PPA) with NextEra Energy in Farmington, Maine, along with four other universities. In the agreement, Amherst purchases 10,000 MWh/yr of solar energy, which offsets the emissions from EverSource purchased energy. The purchase allows us to reduce carbon dioxide emissions by over 3,200 metric tons. This sort of renewable-energy purchase offsets Scope 2 emissions as well as current inefficiencies in the steam cogeneration systems, while on-campus solutions, like geothermal wells, can be implemented.

The New System

According to Amherst’s website, the geo-exchange of energy that the college’s new system will utilize is a natural process that occurs because of the direction of heat transfer. This is why geothermal energy is considered renewable.

In the new system, surface-temperature water will flow into geo- thermal wells and experience geo-exchange, taking on the temperature of the earth belowground, about 50-60 degrees Fahrenheit. The system “allow[s] us to then utilize the ambient air temperature at depth to … preheat or precool,” said Dripps. Once the water has reached this temperature, the pumps will use 1kw of electricity to finish heating the water up to about 90 degrees in order to be pumped back up to the surface and be of use in the low-temperature hot water heating system. In the summer months, a cooling system will work in reverse, bringing the temperature further down from 50 to 60 degrees.

The amount of energy required to bring the water up to temperature is significantly lower than what is needed to produce steam. This ultimately allows the college to use only geothermal and electricity to power the heating and cooling system.

The college has a higher heating demand than cooling demand, particularly in the winter months. That means that the geo-exchange system’s renewability is not in equilibrium, and therefore not optimized. Thus, part of the transition requires the installment of a solar thermal system to prevent the exchange from failing and prevent the ground from cooling too much during our winters as we use heat energy from the earth to warm our system.

This combination of geothermal and solar thermal recharge will account for 100 percent of the cooling demand and 87-88 percent of the heating demand. According to the Integral Group report, the remaining 12-13 percent of our heating demand will need to be covered by switching our fuel from natural gas to biogas.

There are three phases of implementing the new geothermal system. The college is currently in the first stage of construction, in which campus buildings will get a new piping infrastructure to carry heat via low-temperature hot water rather than steam. The second phase will begin in 2025, with the digging of geothermal wells for the vertical, closed-loop system and the connection of heat pumps to the closed-loop system powered by renewable energy. The third phase will be in 2030, and will put together these components: all of the fossil-fueled steam boilers will be shut off, and the campus will only be heated by the new geothermal system.

Amherst has contracted Finegold Alexander Architects to identify code and accessibility issues with specific buildings, and the replacement of the steam and hot water systems for 26 buildings along with a design for the campus Energy Center which will be a “low-embodied carbon structure” that has a green roof and will be constructed using heavy timber. This construction is projected to be completed by 2030.

Why Geothermal Energy?

The transition to geothermal energy will mean the college will reduce its carbon dioxide emissions from 14,000 to 680 metric tons per year just by reducing natural gas alone. The new system is also more cost-effective: It would cost $12,544,456 every 15 years to update all of our cogeneration infrastructure, but with the new geothermal system it will only cost us $4,385,216 every 17 years to update all of our infrastructure (Integral Group).

The college’s transition will be following the example of its neighbor school, Smith, as they started their geo-exchange construction summer of 2022. In the process of meeting their climate action goals, Amherst will hopefully become another successful example of a carbon-neutral campus.

Senior Lecturer in Biology and Environmental Studies Rachel Levin, a member of the Climate Action Task Force, spoke to the broader movement that Amherst is joining. “Geothermal has shown to be really successful in a lot of places,” Levin said, “I know Carleton College has switched to [geothermal] and done a similar approach … I’m really excited to see how [geothermal] progresses.”

Professor of Geology and Environmental Studies Anna Martini, another member of the task force, was similarly excited about the decision. “Geothermal was on the table from the very beginning,” Martini said, “It is the best option for our goal, although it will be a bit disruptive for the next few years. I’m really happy to see the project finally begin, and I'm glad everyone is pushing forward here, even in the face of some economic headwinds. When reducing your carbon footprint, sooner is far better than later.”

“This will go down as one of the most transformational projects the college has ever done, and probably ever will do,” affirmed Dripps. “And it’s history.”