Johns Hopkins Gazette: September 6, 1994

By Mike Field

When Charles Carroll Jr. moved into Homewood in 1802, the new
house came equipped with all the modern conveniences. There
were Argand lamps in the parlor that provided enough bright,
even light to read comfortably by at night; an ingenious
"flushing" chamber pot in the master bedroom that precluded
midnight runs to the outhouse; and somewhere on the grounds--
perhaps near the kitchen--the Carrolls had their very own ice
house, a subterranean vault that servants would fill with
blocks of ice in the winter so that, come summer, the
estate's fashionable occupants could enjoy the uncommon
luxury of cooled drinks and other chilled foods as a way to
beat the heat.
    Times have changed, and the need to provide cooling
capabilities in the heat of summer is no longer considered a
luxury. But the idea of using ice storage as a means of
providing that cooling had long since gone the way of oil
lamps and chamber pots, until recently, that is.
    In December, the university broke ground on its own
high-tech, late 20th-century version of the venerable ice
house. Located in four enormous subterranean concrete vaults,
the new north chiller plant, as it is called, will make and
melt iceberg-sized blocks of ice on a daily basis during the
cooling season to provide much of the air conditioning and
other cooling needs of the Homewood campus.
    "Most of the cooling needs on the Homewood campus are
provided by water that is chilled to 42 degrees Fahrenheit
and then piped throughout the campus in underground tunnels,"
said acting director for engineering services Wendy Pinnix,
who is overseeing the construction of the north chiller
plant, now being built adjacent to the Bloomberg Center,
behind the Athletic Center.
    "In the university's current system, the water is
chilled through the use of huge compressors and refrigerants,
not unlike a home refrigeration system," Pinnix said. "The
cold water is then pumped to the campus buildings, where
tertiary pumps circulate the water through coils within the
buildings' air handling units. In some cases, such as the
lasers in the astrophysics lab, the chilled water is used
indirectly to cool research and scientific equipment."
    The new chiller plant will not replace the existing
system, but augment it, by providing ice--made at night when
electricity rates are lowest--to finish putting the chill in
the campus's chilled water system. "This is entirely a
utility company-driven technology," said Gil Morin, president
and founder of the G.F. Morin Co., which provided the
university with the cooling equipment for the new system. 
    "On a hot summer day, a utility company like BGE will
operate at 100 percent of capacity in order to provide for
all the cooling needs, while at night it will run at
something like 50 percent capacity," Morin said. "In recent
years, the utility companies have been practicing load
management, where they have been encouraging the use of
electricity at night and discouraging its use during the
    By offering substantially lower electricity rates during
the night--and sweetening the deal with generous cash rebates
toward the construction of energy-efficient and load-managing
systems--BGE hopes to be able to accommodate projected higher
energy demands without having to go through the expense and
turmoil involved in building new power plants. In Hopkins'
case, the university will save an estimated $400,000 annually
in electricity, and BGE has committed to a substantial rebate
of approximately $660,000 toward the construction of the
first phase of the $3.4 million project. If all goes
according to schedule, the system will be running by the end
of the year.
    "We built this system bigger than we currently need with
an eye to expanding it in the future," Pinnix said. "When we
bring the system on line, we'll only be using two of the four
concrete chambers to make and store ice. When the university
expands its cooling needs, we'll be able to expand with two
more ice chambers."
    Each concrete chamber is essentially a large, watertight
tank, approximately 23 feet wide by 51 feet long and filled
with water to a 15-foot depth. Each chamber contains four ice
coils made from thousands of feet of coiled steel piping. At
night, giant compressors chill an ethylene glycol mixture to
about 24 degrees and circulate the cold fluid through the
pipes. Gradually, huge tubes of ice form around the coils
until, the next morning, the tank is full of ice tubes,
allowing just enough room for the remaining unfrozen water to
circulate around and through them.
    "The ice water is pumped to a heat ex-changer that in
turn cools the water that circulates through campus," Morin
said. "It doesn't provide all the cooling necessary, but it
greatly reduces the amount of work the regular chiller
compressors must do, and so saves substantial amounts of the
expensive daytime electricity."
    The new Hopkins chiller plant is just one of a half
dozen or so similar plants now coming on line in the
Baltimore area. BGE estimates that in the past 10 years,
about 40 such systems have been put in operation, including
sites at the Baltimore Museum of Art, Union Memorial Hospital
and the Applied Physics Laboratory. "There is nothing unique
or unusual in the technology needed to make ice," Morin said.
"What's new and somewhat novel is the production and
collection of ice at off-peak hours for use during the
hottest part of the day."
    The Homewood campus north chiller ice storage facility
may be new, but its basic premise is hardly novel. Ice in
summer heat is a wonderful way to keep cool, as any of the
fashionable men and women sipping their chilled drinks on the
Homewood veranda 200 years ago would have readily agreed.

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