Energy storage can help reduce the
energy and operating cost of a a school or university so it can reinvest those dollars toward improving the education of it’s students.
Fossil Ridge H.S.
Fort Collins, CO
What is energy storage and how does it work? energy storage is a proven
technology that takes advantage of low-cost, off-peak electric rates
to produce cooling energy for use when electric rates are higher. A
facility’s chiller is used to charge
CALMAC’s ICEBANK® thermal energy storage tanks with ice during less-expensive, off-peak hours at night. The ice is stored in the ICEBANK
tanks and then used the next day during the discharge cycle to cool
the school during on-peak hours. Click here (PDF, 371 Kb) for
system schematics and a technical review of the energy storage process.
Operating chillers during nighttime hours improves energy efficiency
by 2 to 8 percent over non-storage systems operating during the day.
Dry-bulb temperatures are about 20°F lower and wet-bulb temperatures
5°F lower at nighttime hours, compared to daytime hours. Nighttime
operation improves the efficiency of all chillers, but especially
air-cooled chillers because the condensing temperature is controlled
by ambient dry-bulb temperature.
There are at least three energy storage strategies to consider: full storage,
partial storage, or a combination. Full storage shifts a building’s
entire cooling load to off-peak hours. The building’s chiller only
runs at night in order to charge the ICEBANK tanks. During the
discharge cycle, the stored ice is used to cool 100 percent of the
building’s load the next day. Full-storage systems offer the best
savings and simple operation.
With partial-storage, ICEBANK tanks work in tandem with the chiller.
The chiller charges the ICEBANK tanks at night and continues to run
the following day during the discharge cycle. During the discharge
cycle, the chiller cools up to 70 percent of the facility’s load and
the stored ice cools the remaining load.
A partial load energy storage system configuration enables chillers to operate at
or near full load continuously, thus eliminating the inefficient cycling
and capacity modulation that accompanies part-load operation and normally
causes a chiller to operate at peak efficiency only 25 percent of the time.
Lastly, tighter construction in newer school buildings and humidity
management are increasingly important. Energy storage provides engineers with
a tool for reducing humidity levels in order to improve the comfort
of students. For example, “Cooling the primary air to 45°F (versus
55°F in a conventional system) will lower conditioned-space
relative-humidity levels from 60 percent to 35 percent, which
generally improves the perceived comfort of occupants.” (Federal Technology Alert) With better comfort
comes increased productivity. Teachers teach better and students
learn better in high-performance school facilities.
Click here (PDF, 371 Kb) for system schematics and a technical review of the OPC process.
Additional design engineer benefits
- Provides a design with a chiller that is 40 to 50 percent smaller, to minimize inefficient operation of oversized equipment with minimal risk.
- Thermal energy storage design is similar to a chilled-water system and is not complicated.
- Provides customers with a demand-responsive cooling system.
- Provides customers a cooling system with fuel-source flexibility, on-peak or off-peak energy.
- Offers architects a path to ASHRAE 90.1 compliance or improved LEED™ ratings.
- Added design costs, if any, can be easily paid for with life-cycle savings.
- The size of air handlers, motors, ducts, and pumps can be reduced by 20 to 40 percent, which saves design time.
- CALMAC can provide a wealth of information to help engineers efficiently design a energy storage system.
- Click here for a complete list of other benefits.
thermal energy storage is just not worth the trouble. CALMAC’s
technology and the tools available to help design, install, and operate
Thermal energy storage systems have changed dramatically over the years. Energy storage can be
reliably and affordably applied and is easy to operate. Saving significant
energy costs is always worth the effort, particularly in today’s
challenging economic environment. Partial-storage energy storage systems can reduce
a school system’s energy costs by 20 to 60 percent. Energy storage also has
environmental benefits beyond the meter, and
other benefits that can help school districts negotiate better rates
with their energy provider.
Mike Boehm, maintenance and operations supervisor for the aforementioned
Montgomery school system, said, "We were
able to shift 120 kilowatts off peak. During the fall and spring, I can
usually operate the air conditioning on ice alone and never bring on the
chiller during the day. With a demand rate of $9.15 kW, we can achieve a
two-year payback over a conventional chilled-water system with demand
Click here for a partial listing of energy storage projects.
Please click here to contact any of CALMAC’s regional managers for
additional information or questions.