College considers new heating system

by Zachary Benjamin | 2/22/16 8:32pm

As winter approaches each year, Dartmouth is forced to increase its energy usage to keep its inhabitants sheltered from the cold. However, many students remain unaware of how the College’s heating system functions, or about what technologies could be adopted to make it more effective.

Heat for the College originates with No. 6 oil, which is heated to 160 degrees and pumped underground to the College’s power plant, said Frank Roberts, associate vice-president for facilities and operations management. At the plant, it is burned in boilers that generate about 450 pounds of steam. The steam can then either be used to power a turbine and generate electricity or sent directly to other buildings on campus to provide heat.

Most residence halls use the steam for heat directly by moving it through radiators on the perimeter of the building, though some newer buildings send the steam to an air handler or convert the steam to hot water, he said.

Though the underground steam distribution system is on year-round, helping to produce hot water for the buildings, the heating systems in the residence halls remain off for about half the year. This is because the pipes in the walls will overheat the buildings if the system is left on all year, Roberts said. The process of deciding when to turn on the heating system is thus a complicated one because once it is activated it will not be turned off until the weather heats up again. For this reason, facilities and operations management will wait to activate the heating system until a period of consistent cold weather sets in.

The current system burns about 3.7 million gallons of oil each year, Roberts said, and cogenerates about 13 million kilowatt-hours of electricity. The College buys an additional 50 to 55 million kilowatt-hours each year that cannot be cogenerated.

Though Dartmouth continues to rely primarily on steam to power its heating system, the technology is not without its flaws, Roberts noted. For example, steam can be a relatively inefficient medium for heat transfer that is difficult to keep insulated. It is also difficult to store energy using steam, meaning that the amount generated needs to be closely matched with the amount of energy demanded to keep energy usage efficient. Finally, pipes need to be placed at particular angles to take advantage of gravity, which is required to move steam, he said.

For these reasons, the College is beginning to look into transitioning to a hot water-based heating system, Roberts said. This technology has several advantages over steam: it is easier to insulate and simpler to maintain, it can store energy via hot water tanks for later use and it allows more flexibility in pipe placement.

“It would bring our heating distribution into the 21st century,” he said.

Though there is no set plan for when the transition would occur, officials have begun studying the timeline for such a transition and generating a financial analysis, he said. After a plan has been developed and a cost estimate formed, the process of approval would begin. Roberts estimated the entire project, from the start of planning to the end of construction, would take about five years.

Other universities have made the switch to similar systems in recent years. Stanford University, for example, finished construction on a hot water heating system for its campus in April of 2015. The process took about five years from planning to completion, said Joseph Stagner, Stanford’s executive director of sustainability and energy management.

Stanford’s goal was to increase the efficiency of its heating system by using heat recovery technologies rather than fossil fuels to meet the university’s heating and cooling needs, Stagner said. After surveying their energy usage, Stanford determined that they could use the excess heat from its heating systems to meet their needs using a heat pump. Because heat pumps run using hot water, not steam, it was also necessary to transition the campus to a hot water heating system, Stagner said.

The new system has allowed Stanford to greatly reduce its carbon emissions. From June to mid-November of 2015, no fossil fuels were burned on campus except for those necessary to run a small handful of labs, Stagner said. Instead, heat recovery technologies were used to generate power and meet all of the university’s heating and cooling needs.

Though the university has not yet performed a full audit on their energy efficiency, there has been about a 50 percent reduction in carbon emissions, said Lauren Hennessy, Stanford’s outreach and program manager for the office of sustainability. Further plans to implement solar panels will continue to reduce carbon emissions by an estimated 68 percent, she said.

Stagner noted that some people believe such a system would not be feasible on the East Coast, with significantly colder winters than California. However, officials from East Coast schools, after studying Stanford’s system, concluded that about 50 percent of their universities’ annual heating load could be powered via their waste heat, he said. He pointed to a hybrid system with some heat recovery, or using geothermal energy to power heat pumps, as a potential realistic option for Dartmouth.

Switching to a hot water system could increase the efficiency of Dartmouth’s distribution system alone by about 15 percent, Roberts said. Converting buildings on campus to also use hot water could generate additional efficiencies of about 10 to 20 percent, he said.

Currently, 122 buildings are served by the heating distribution system. Forty-nine buildings use only steam for heating, 55 use a mix of steam and hot water and 18 use hot water only, Roberts said.

The process of converting buildings and the heating system is part of a larger move towards energy conservation by the College, which was started in 2008 by then-president Jim Wright. At the time, the Board of Trustees approved $12.5 million for energy-saving updates to existing buildings.

Catherine Rocchi ’19, a member of Divest Dartmouth, said that she supports the move towards a hot-water based system. Though noting that her organization is not officially involved in promoting such initiatives, focusing instead on convincing the College to divest from major fossil-fuel companies, she said that she believes most members would support such a shift, given the increased energy efficiency of such a system.

In 2014, out of 173 schools, Dartmouth ranked 124th in the Sierra Club’s eight listing of sustainable schools, which looked at energy use, recycling and food sourcing amongst other factors.

Going forward, the College will seek to improve its sustainability by building more efficient buildings, maintaining and replacing older systems and engaging in energy conservation projects, Roberts said. He emphasized the importance of working on multiple dimensions when seeking to improve energy efficiency across the campus.

“For Dartmouth to continue to conserve energy, it’s going to have to be a multifaceted approach,” he said.

Correction appended (Feb. 23, 2016):

This article incorrectly stated that the College buys an additional 50 to 55 kilowatt-hours each year that cannot be cogenerated. In fact, the College buys an additional 50 to 55 million killowatt-hours annually.