is pumped back into the ground untouched (see Figure 1).
Again, what is unique about Multifilm’s system is that it is used to cool
its machinery, as well as its HVAC.
old chiller anyway, so this was the perfect opportunity to try something different and to make a substantial impact
on our energy consumption and our carbon footprint. Geothermal emerged as
a much smarter option.”
Comparing Processes
Energy Consumption. The company compared the energy efficiencies of a new
chiller and a geothermal system. “On a
modern chiller, we were looking at an
energy reduction of around 50 percent,
which is terrific. But with geothermal,
we were looking at 85 percent. That’s
just enormous,” Mannertorp said.
A geothermal system offered other
benefits as well. A chiller must run
24/7, whereas the geothermal system
needs to run only when the plant and
equipment are operating, Mannertorp
said.
Minimal Repairs. A third consideration was that a geothermal system
would require only minimal, relatively
inexpensive maintenance and repairs,
because it primarily comprises pumps,
motors, and valves. “There’s nothing
major that would cause you to rip out
the whole system and put in something
new,” Mannertorp said.
Long Life. Furthermore, a geothermal system has longevity. “The lifetime
on chillers is not that great. The lifetime
of groundwater is very long. It’s been
around for thousands of years,” Mannertorp said.
Freon-Free. Finally and significantly,
a geothermal system does not need to
use a coolant like Freon, as do chillers
and air conditioners. “Freon is a very
aggressive greenhouse gas,” explained
Mannertorp. “We had to get rid of the
Makeup Air
Outside Air
Gas Boiler
Cooling
Process
Winter Boiler
Divert Loop
HVAC Air Handlers
Plumbing Wells
Heat Exchangers
Recharge Wells
Filters
Standing Water Level
Pumped Water Level
Aquifer
Pump
Figure 1
The groundwater supply goes through a series of heat exchangers, which transfer the
53-degree temperature to another water circuit that cools the plant’s machinery as well
as its air.
The Project Begins
The conversion from chiller to geothermal was initiated in late 2008. The
uniqueness of the project did not come
without risks, and most contractors and
engineers that the company consulted
were hesitant to take on the project,
Rogers said. “This type of geothermal
system isn’t something you can buy off
the shelf. We had to design our own
system and gather our own team of
experts.”
Assembling Expert Design Team.
The manufacturer formed a team of experts that included Clive Maidment, a
British water biologist consultant with
extensive experience in water and energy management; Rafal Kozlowski, a
thermal energy expert; and Multifilm’s
own David Rohrschneider, vice president of operations and also a co-owner;
and Manner torp.
It was Maidment’s role to talk to
the authorities, Mannertorp said. “How
do you get a permit to do this? What
grants are available? How do you do
a prestudy? We received our permit
in days because he talked to the right
people and went about it the right way.”
One important caveat to obtaining
the permit was that the groundwater
could never touch the machinery. The
Multifilm system was designed to comply with that requirement.
Designing the Duo-geothermal System. The design stage spanned several months. The system is engineered
so that after the cool groundwater is
pumped up from three wells that access
the underground aquifer and through
a number of heat exchangers, it is
pumped underground again; so groundwater just flows in and out. The heat exchangers transfer that cool temperature
