POWER October 2021 - 20

FOCUS ON O&M
Upgrading a Campus
Energy System as Part of a
Carbon-Reduction Effort
Educational institutions increasingly are
upgrading their physical utility infrastructure
to become more efficient in their
use of energy while addressing the reliability
of the energy supply on their campus.
It's a trend across the country, and
globally, as campuses seek ways to reduce
their carbon footprint and their energy
costs while increasing resiliency in
the wake of increased storm intensities.
Wellesley College in Massachusetts, a
renowned institution considered one of
the top liberal arts colleges in the U.S., is
an example. In the fall of 2020, Ameresco,
an advanced technology integrator specializing
in energy efficiency and renewable
energy, was selected to provide clean
technology solutions to replace Wellesley's
antiquated Central Utility Plant.
The partnership made sense on several
levels. Ameresco's innovative approach
matched well with a college known for
its progressive sustainability policies and
history of illustrious alumnae, including
environmental activist Marjory Stoneman
Douglas, astronaut Pamela Melroy,
and politician/diplomat Hillary Rodham
Clinton. By implementing the proposed
energy infrastructure upgrades, the institution
is benefiting from a significant
cost savings, increased resiliency-and
most importantly-supporting the college's
efforts to meet its environmental
sustainability objectives.
" At Wellesley, we believe that responsible
stewardship begins at home, and
are committed to reaching efficiency
goals, " Dave Chakraborty, assistant vice
president for facilities management and
planning at Wellesley, said in a statement
earlier this year when the college
announced details of the project. " This
project will move Wellesley forward towards
a more sustainable future and
helps achieve our goal of reducing campus
greenhouse gas [GHG] emissions
37% by 2026, as compared to the institution's
2010 baseline. "
Replacing an Aging Facility
Plans for an alternative to the aging
energy facility began back in December
2017. At the time, Wellesley had a
reciprocating engine-driven combined
heat and power (CHP) facility with a vintage
chiller plant that ran continuously
on natural gas. Since the cogeneration
plant had been running for more than
20 years-24 hours a day, seven days a
20
4. A Cummins natural gas-fueled generator
is moved into the new peaking power plant
at Wellesley College in Massachusetts. The
generator is among the equipment used to replace
an aging energy system at the campus.
Courtesy: Ameresco
week, 365 days a year-all the associated
equipment had reached the end of
its useful life.
Realizing it was time for a change but
hesitant to work toward any plan that
proposed complete removal of the plant,
Wellesley officials wanted to develop a
road map that reduced the use of natural
gas in compliance with its carbon-reduction
efforts and maintained the lowest
energy costs. Ameresco devised a plan
to use proven advanced technologies
that would meet these objectives.
Equipment installations at the plant
included 4 MW of natural gas-fueled reciprocating
engine generators (Figure 4),
paralleling switchgear, 800-ton efficient
electric chillers, a 600-hp firetube pony
boiler (Figure 5), a five-cell cooling tower,
and a 4,000-ton thermal energy storage
system. A key component of this plan
was to operate the project only in a peaking
capacity. This mode prioritized carbon
reductions while ensuring the lowest
utility rates. This plan resulted in a power
plant that only operates a few hundred
hours a year as is necessary to reduce
the peak utility electric demand requirement.
This has reduced the college's use
of natural gas by almost 90%.
By utilizing the new peaking power
plant, boilers, electric chillers, cooling
thermal storage, and absorption chillers,
Wellesley College can effectively manage
its utility electric demand, its power
usage, and reduce its GHG emissions.
The thermal energy storage system operates
the electric chillers during lowcost
electric periods, stores the cold
water underground, and then allows for
the low-cost cold-stored water to be utiwww.powermag.com
5.
This boiler from Johnston Boiler Co. is
among the upgrades at Wellesley College's
campus utility facility. Courtesy: Ameresco
lized when it would otherwise be very
expensive to rely on the electric chillers.
Cost Savings, Emissions
Reduction
Avoiding peak demand charges by generating
power only during the hottest summer
periods is saving the college nearly
$1 million annually. The new generation
facility is a dispatchable resource hardening
the college's defense to utility disruptions.
And the overall reduction in carbon
emissions (estimated at 5,630 metric
tons per year) is helping Wellesley meet
its carbon-reduction goals.
Ameresco, which has worked with
a variety of municipal utilities across
North America and the UK, used its
experience in this domain to work
with Wellesley Municipal Light Plant
(WMLP), the town-owned utility, to help
maintain Wellesley's lowest power rate.
Most of the output from Ameresco's
working renewable energy power plants
across the U.S. is sold to local municipal
utility companies, so the renewable
energy company is no newcomer
to collaborating with these groups. In
this case, involving a complicated set of
solutions, a tremendous amount of coordination
from all parties was needed
to enable alignment on a project that
would benefit all key stakeholders.
For colleges and universities across
the country, marrying cost savings and
sustainable solutions (while improving
resiliency) is a universally held common
goal. Today, most institutions understand
the need for action, but identifying
solution sets that speak to both
priorities can often seem like a conversely
related and overwhelming task.
Construction (Figure 6) on Wellesley
POWER | October 2021
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POWER October 2021

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