Seven geothermal fields are tucked under the stately campus of Harvard University. The institution has a 2016 goal to reduce absolute greenhouse gas emissions by 30% from a 2006 baseline. Geothermal is one of several key strategies to satisfy energy demands while continuing to shrink Harvard’s carbon footprint.
“Harvard actively invests in the transition to renewable and alternative energy sources as part of our aggressive climate goal,” explains Heather Henriksen, Director of the Office for Sustainability. “Geothermal, in addition to on-site solar and cogeneration, are opportunities to accelerate the progression to clean energy.”
“As the university continues to grow, geothermal can be an attractive alternative where extension of the district energy system may be cost-prohibitive,” according to Jeffrey Smith, Director of Facilities Maintenance Operations for Harvard University Campus Services. “The environmental benefits and aesthetic profile of geothermal offers an attractive alternative to conventional cooling towers.” Switching to geothermal also minimizes HVAC equipment clutter and mechanical noise on campus, adds Lester Gerry, Director of Facilities Management at the Harvard Radcliffe Institute for Advanced Study.
As the urban campus is densely populated with structures, most of Harvard’s geothermal installations use open loops. One of the largest fields, the Radcliffe system, was installed in 2006. Five additional wells were added in 2009 to serve Byerly Hall and eventually Fay House in 2012.
“An interconnecting chilled water loop was installed in 2014, allowing all main buildings on Radcliffe’s campus to use geothermal. This one field serves approximately 220,000 square feet of space, and energy consumption for heating and cooling is down over 60%,” explains Gerry. “We continue to maximize the geothermal efficiency by using the heating side well water in the winter for archival vault cooling. This saves energy on direct expansion (DX) cooling and aids the wells by adding heat energy.”
The sole closed-loop system serves the Arnold Arboretum (image on the left) and Weld Hill Research Center, where there was enough space to install the system. It has 88 vertical wells that are 500 feet deep and 11 heat pumps of 35 tons each. As greenhouses have significant cooling demands and laboratories require additional ventilation, geothermal minimizes the site’s energy profile.
The fields also serve as a living lab for engineering students. For example, a team of engineering undergraduates from the John A. Paulson School of Engineering and Applied Sciences ran an analysis on the Byerly system to see if it could support an additional load from the adjacent Fay House without losing any efficiencies. Their modeling determined that the Fay House could replace its conventional HVAC units without having to drill new wells just by adding three pumps.
Geothermal has also provided the university with valuable O&M learning opportunities, particularly as the school handled the system design. Several installations have required additional equipment purchases and reengineering to fine-tune performance. “Rather than see these redesigns as setbacks, the university transparently discusses these challenges so others can learn from our findings,” notes Smith.