POWER October 2020 - 17

FOCUS ON O&M
more than 20 years, and has a levelized
cost of energy (LCOE) of less than $0.02
per kWh (about one-tenth that of lithiumion
batteries).
3. There are many advantages to using
TES systems for cooling. More efficient refrigeration
means lower energy costs. Using
off-peak electricity to store energy for use
during peak hours helps reduce the daytime
peaks of power consumption. Courtesy: Viking
Cold Solutions
equipment, the flexibility to participate in
programs is limited, and carries risk.
Until recently there was a void of
application-specific energy storage
technologies for C&I refrigeration that
provide significant capacity and discharge
duration (see sidebar). Conventional
efficiency technologies that
For C&I Flexibility and Efficiency,
Timing is Good
In many states, such as California and
others in the Northeast, utilities have implemented
time-of-use electricity tariffs
that provide powerful incentives for C&I
cold storage operators to shift their electricity
use to off-peak hours. Some operators
have resorted to using a technique
known as flywheeling; sub-cooling the
food below optimal temperatures, then
cycling off refrigeration equipment during
expensive time intervals and letting
the temperatures increase. However, cycling
food like a battery comes at a cost
to food quality and actually increases
overall electricity consumption.
TES systems provide time-of-use flexibility
with much greater capacity and
much longer discharge cycles than lithium-ion
batteries. For example, at Dreisbach
Enterprises, a 93,000-square-foot
TES systems provide time-of-use
flexibility with much greater capacity
and much longer discharge cycles than
lithium-ion batteries.
reduce consumption such as LED lighting,
variable frequency drives, and building
envelope enhancements, make only
marginal impact or have already in large
part been implemented.
Recently, utilities and facility managers
have begun incorporating long-duration
energy storage solutions (four or more
hours of discharge) designed specifically
for low-temperature C&I refrigeration.
These behind-the-meter thermal energy
storage (TES) systems (Figure 3) have
demonstrated their ability to give utilities
greater control over the peak electricity
demands of refrigeration for up to 13
hours per day, while offering cold storage
facility owners the benefits of lower energy
costs, increased resiliency for food
quality assurance, reduced emissions,
and-something not many storage technologies
offer-efficiency.
Additionally, because these systems
are non-mechanical and designed exclusively
for refrigeration applications, TES
stores more energy and discharges for
many more hours, has a system life of
October 2020 | POWER
industrial facility in the San Francisco Bay
Area, the owners found that over the past
few years TES provides sufficient energy
storage to shed 300 kW to 500 kW for
13 hours per day, six days a week. This
reduction in demand is accomplished
while also improving temperature stability
by 50%, and thus avoids using the
Phase Change
Material for Thermal
Energy Storage
Phase Change Material (PCM) is a
substance with a high latent heat of
fusion that remains near a constant
temperature while storing and releasing
large amounts of energy. During
its transition between solid and liquid
states, Viking Cold Solutions PCM
absorbs up to 85% of heat infiltration
and maintains more stable temperatures
to better protect food products.
This environmentally friendly, foodsafe
PCM is engineered by Viking
Cold Solutions to freeze and thaw at
the desired temperature setpoint of
the customer's freezer.
The technology is being used at
a frozen food distribution center
owned and operated by Dreisbach
Enterprises in Richmond, California.
Viking Cold Solutions' patented thermal
energy storage (TES) system
was installed in a 93,000-squarefoot
low-temperature freezer, part of
a facility also comprised of mediumtemperature
refrigerated storage,
dry storage, and office space. Refrigeration
for the low- and mediumtemperature
cold storage rooms
was provided by a central ammonia
refrigeration plant composed of multiple-staged
screw compressors and
water-cooled condensers.
The installation was part of a measurement
and verification (M&V) study
of Viking Cold Solutions' TES technology
installed in an industrial low-temperature
cold storage warehouse. The
objectives of the M&V study were to
determine the effectiveness of TES
on energy efficiency and temperature
stability with an ammonia-based
refrigeration system. The M&V study
concluded that TES provided a 43%
decrease in peak period consumption
and a 29% decrease in peak demand
while improving overall temperature
stability by 50% in a low-temperature
warehouse.
4. TES cells located near the top of the warehouse
can provide energy and cost savings.
The cells in this configuration absorb most of
the heat infiltration, and consolidate it near
the top of the room, directly in the refrigeration
airflow. Courtesy: Viking Cold Solutions
www.powermag.com
food as the battery when flywheeling.
The same facility also saw a 43%
decrease in consumption (efficiency
gains) during its 13-hour peak period,
without using more energy during the
remaining 11 hours of the day. In fact,
total freezer energy consumption was
reduced by 35%.
TES technology improves an exist17
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POWER October 2020

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