As an early adopter of microgrids and distributed energy, Harvard University continues to lead the way in demonstrating energy security, reliability, sustainability and resilience for higher education.
Harvard’s history of producing and distributing power, heat and water dates back a long way. Having been a district heating customer since the early 20th century, the university purchased the Blackstone steam heating plant from the local utility in 2003 when Massachusetts restructured power industry ownership rules.
The university installed combined heat and power (CHP) in 2009, with a second addition in early 2016, according to Robert Manning, director of Harvard University Engineering & Utilities. Today, one of the CHP units serves a 7.5 MW load pocket as a microgrid, capable of both islanding and blackstart (automatic startup) service.
“Harvard’s Cambridge campus has always had its own internal electric grid, allowing greater response to campus needs, as well as ensuring high levels of maintenance and renewal on our distribution system,” Manning told Microgrid Knowledge. “Building and operating a microgrid is a complex endeavor, requiring skilled internal resources as well as key partners in all aspects of the system life cycle – design consultants, equipment vendors, controls, operations, maintenance, etc.”
Making the most out of combined heat & power
Run by Harvard Energy & Utilities, which manages the production, procurement, distribution and billing of utilities for much of the university’s Cambridge and Allston campuses, the CHP plants each serve different load pockets.
The first, a 7.5-MW combustion turbine equipped for heat recovery, effectively acts as a combined cycle generator. The new CHP unit replaced an aging boiler and was sized to meet minimum heat loads so that it runs year-round.
The second, a 5-MW back-pressure turbine, serves loads based on the output of the district energy system’s thermal steam generator. The higher the steam pressure and flow, the higher the electrical output. The unit doesn’t operate in summer months, when the steam load is very low, Manning said.
“Heat recovered during power generation is used to convert water to steam, which then flows through the back-pressure turbine eight months of the year, so we can run in a combined cycle mode,” Manning said.
Harvard uses primarily natural gas for the systems, but also maintains a backup supply of Number 2 fuel oil. All of the CHP and boilers are dual-fuel. “If necessary, we could operate for many days on our backup supply,” Manning said.
All told, the university’s energy modernization projects are yielding substantial cost savings, as well as helping improve human and environmental conditions and quality of life.
“This is behind the meter, so the value of electricity produced is far greater than just the commodity portion – we have reduced our demand charges and annual capacity costs. And there are additional financial benefits via Massachusetts alternative energy credits, which we get for electricity produced via CHP,” he said.
Harvard Engineering & Utilities District Energy Facility and Microgrid
Scope and scale
Sustainable, resilient energy, heating, cooling and hot/chilled water production, procurement and distribution for some 160 buildings at Harvard’s Cambridge and Allston campuses in support of university and Cambridge municipal renewable energy and sustainability goals.
- Blackstone thermal power plant (95 percent natural gas-fueled):
– 7.5-MW natural gas combustion turbine-based electric microgrid with “blackstart” capability
– 5-MW CHP backpressure turbine fueled by heat from the 7.5-MW combustion turbine
– Four boilers with dual-fuel capability and one HRSG
- Two interconnected chilled water plants
- Integrated distributed solar PV
- Multiple line distribution backbone in walk‐through tunnel system
- Single-line radial system in other areas
- Overall grid electricity consumption: 236 million kWh, including two CHP microgrid load pockets
- Blackstone thermal power plant fuel input: 1.2 million MMBTUs per annum
- Central plant cooling: 1,057,000 ton‐days
- Ensures total reliable “island” microgrid service during electric or gas grid blackouts via the two CHP units
- Enhanced energy efficiency; reduced energy consumption
- Lower, and less volatile, fuel costs
Reduced greenhouse gas emissions
The two CHP projects added local electric production capacity to the district energy microgrid. Both follow through on Harvard’s broad-based efforts to increase energy efficiency at its steam-fueled thermal power plant, according to Manning.
The two new generators are connected in a way that enhances grid and on-site resilience in the event of a power outage. In addition, Harvard has incorporated a number of smaller distributed generation units on its internal grid, part and parcel of achieving the university system’s sustainability goals, Manning said.
For example, the campus has small solar photovoltaic systems throughout, which have received incentives from the state. The CHP units also receive incentives by way of credits offered through Massachusetts’ alternative energy portfolio standard program.
Harvard worked closely with its local utility on both CHP modernization and upgrade projects, carrying out interconnection studies so as to ensure that equipment and infrastructure were seamlessly integrated, secured and well protected, according to Manning.
Manning shared some key insights, and lessons learned, about operating microgrids and distributed energy.
“We have found that extra time spent in the beginning, looking at the feasibility and other upfront studies and comparing multiple options can ensure greater opportunities for success,” he said. “One key takeaway is that no matter how much you can control on your own system, you still need to be prepared for issues beyond your control, such as interconnection issues that may not be fully knowable until you get to certain milestones.”
He added: “We try to identify as many of these potential obstacles in the early stages as we can, but we also budget some time for the ones that will only be uncovered as the studies progress. On the plus side, as mentioned before, if you design it correctly it will be an ‘all of the above’ type benefit realization.”
Learn more about New England’s most innovative microgrids and distributed energy projects. Join us at Microgrid 2017, Nov. 6-8, in Boston.