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Published on June 17th, 2016 | by Jake Richardson

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JCPenney Reduces Electricity Costs With Ice Storage Technology

June 17th, 2016 by  

JCPenney’s headquarters in Plano, Texas, has employed ice storage technology made by CALMAC for 25 years, in order to reduce electricity costs. Last year, about $100,000 was saved. Mark MacCracken, CALMAC’s CEO, answered some questions for CleanTechnica.

What is the technology that is used?jcpenneytanks copy
The technology that is being used is CALMAC’s IceBank® energy storage tanks that utilize an ice on coil internal melt technology. Essentially the ice-based energy storage tanks act as a battery for a commercial building’s air-conditioning system, allowing cooling to be created and stored at night in the form of ice and for use the following day.

What kind of maintenance is required?

For an ice-based system, maintenance is minimal. Once a year, the water level of the tanks needs to be checked to ensure that it is filled to the proper level. At that time, the concentration and health of the heat transfer fluid should be checked and treated, if necessary. Since there are no moving parts in the storage tanks, there is virtually no more “wear and tear” than with a non-storage system. (For a CALMAC® IceBank® Ice System this is true. Other manufactures require different and more extensive maintenance)

What size are the containers used to store the ice?
The IceBank tanks are cylindrical in shape, which is the most efficient shape for liquids. They are 8.5 feet tall with a diameter of 7.5 feet. To get a sense of how much space this is, two tanks could fit within a typical parking space. The required space is approximately the same ratio of space required for a water heater in a 2,000 sq. foot home.

Is the technology located on the rooftops?
The tanks are located in the facility’s mechanical room, however, the IceBank tanks can be located almost anywhere, including outside on a concrete slab, partially buried, fully buried, or on a roof of buildings.

Does it assist air conditioning systems by reducing the amount of electricity they use?
The IceBank system allows a building to shift the electricity consumption required for a portion of the daytime cooling load to nighttime hours. This enables better utilization of low-cost electricity and wind energy by the utility, since wind mainly blows at night. Shifting consumption to night-time hours also allows a building to avoid energy consumption during peak hours. Electricity generation during daytime peak hours is typically not very efficient or environmentally friendly. The oldest and typically the most polluting fossil fuel plants are used to meet the peak demand that is caused by air conditioning in the heat of the day. Adding more thermal energy storage will replace these peaking power plants without having to add more power generation to the grid. According to the California Energy Commission, during low demand, off-peak periods, 10-30% less energy is needed to deliver power, because off-peak power plants (known as baseload plants) are that much more efficient. Thermal energy storage reduces source energy consumption as well.

Is the typical annual savings about $100,000?
Savings vary depending on the size of an installation and the utility rates that are being implemented. However, once peak demand charges are factored into the price of energy for commercial buildings, cooling is 50% cheaper during nighttime hours when compared to daytime hours. This statement holds true even when buildings have a demand charge with a “flat rate” charge for electricity. We have many projects that save over $1,000,000 per year.

What is the total amount of savings over the 25-year period?
We are unable to provide an estimated total savings for the 25-year period because building usage changes and electricity rates and grid savings programs change over periods of time. Generally speaking, over the last forty years, according to the Edison Electric Institute (EEI), night-time electricity, when converted to today’s dollars, has not increased in cost.

Is the Plano, Texas, site the only JCPenney location using this technology?
The Plano, Texas, site is JCPenney’s corporate headquarters building and not a retail location. This is the only site currently using CALMAC’s thermal energy storage solution. In many malls, however, developers use packaged units which are low in first cost. Some retailers own or lease properties for a long time and will invest in engineered cooling systems. CALMAC has over 4,000 installations across more than 50 countries. Some high-profile buildings in New York City include Rockefeller Center, Bank of America Tower, and 55 Water Street. Some retail customers include IKEA, KOHLS, WalMart, Costco, and Nordstrom.

Are other sites or stores going to install their own systems?
There are no plans for other JCPenney sites at this time, which is understandable. Our product does not apply to all buildings for certain technical reasons (the system needs to be based on a central chiller and not unitary rooftops).  Most of JCPenney’s stores are not central systems.

How much water is used each day, and is the same water used repeatedly?
Zero. Yes, the water within a CALMAC IceBank system never leaves the tanks and is reused every day by freezing or thawing. During the off-peak hours, a glycol solution is cooled by a chiller and then circulated through several miles of tubing within the IceBank tank. This freezes the roughly 1,600 gallons of water which surrounds the tubing within the tank. When it is time to cool a building the process works in reverse. The ice that was built the night before is used to cool the solution. The solution is distributed to an air-handler coil where it cools the air.

Is the system rated in kilowatts and megawatts or kilowatt-hours and megawatt hours?
IceBank systems are for cooling, so mechanical engineers rate them in a combination of ton-hours and tons (and temperature required). One tank can have 160 ton-hours, or said another way, 20 tons of cooling over 8 hours or almost 27 tons over six hours. Electrical engineers or power engineers look at watts so they look at the storage differently. They look at it in terms of how much is the storage displacing electricity consumption and demand. Each building uses different electric cooling technologies so in terms of watts, it depends. However, as a rule of thumb one tank can remove about 20 kW to 25 kW of electricity for about 8 hours. As the press release states, the JCPenney installation stores nearly 4 MW of cooling.

Image Credit: CALMAC





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  • CU

    I’m waiting for the first time when the AC-system will be loaded by cheap electricity from PV in the daytime for the evenings.

  • Jessee McBroom

    This system would seem to be ideally suited to skyscrapers applications.

  • jeffhre

    Great time based shifting of loads, and using the efficiency of facing away from the sun when removing heat. Has been around a long time and would be great to apply it more universally, but you must have a central chiller based system to use it.

    • Matt

      There are some (not as efficient) that do it on the roof next to each unit. One is ice bear, but likely others.
      https://www.ice-energy.com/technology/
      But a lot of big buildings have central system, and if they do even older building can normally find some space in the basement to use one. If you have a below ground parking garage, can be just closing a few parking spots.

      • jeffhre

        Thanks Matt. I didn’t realize the ice bear was capable of that level of application.

  • Matt

    Very cool and “old” tech. You get an even bigger benefit if you plan this in a new building, since then the AC system can be sized smaller. Add on variable speed fans/compressors and high efficiency heat pump / AC and you can shift massive loads. Freeze it at night when outside temp lower and power price is cheaper, use during day.

  • Andy

    Pretty cool tech

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