One of our projects: Unique cooling system

Just a little blurb on one of our completed projects.

This unique cooling system—it’s the only one in the company to date—makes sense for the building from both a cost standpoint, and from the standpoint of being a good neighbor. We expect to save on utility bills in the long run while reducing its environmental impact. The three-story building will use about half the electricity of a similarly sized building during daytime hours.
That should save thousands of dollars annually, especially in Hawaii which has the highest electricity prices in the nation and is dependent on oil more than any other state.
The system recharges or creates the ice at night during off-peak energy hours. There are four dozen 1,700-gallon thermal tanks on the roof of the store, where the ice is created and stored. A glycol-water solution is chilled to 20 degrees and passes through hoses in the storage tanks, freezing the water.
As the ice melts during the day, it keeps the solution cool, which is then sent through pipes where fans send chilly air into the store. The fans adjust accordingly to the temperature in the store.
The technology shifts the heaviest amount of energy use to a time of day where it's not going to have as much impact on the rest of the area’s electric system. In a conventional system, compressors work the hardest during the day when it's the hottest.
The local utility is giving the company a credit of three cents per kilowatt hour during nighttime hours when the ice is being created.


  • Ashraf HZ
    Ashraf HZ
    Wow, interesting stuff! Great work Gohm 😉
  • gohm
    Thanks it is a very unique system. I'll post some more projects we are working on later.
  • Ashraf HZ
    Ashraf HZ
    By the way, is it possible to post some images of it? Or perhaps a control flowchart? A visual representation is always good 😀

    Looking forward to see the other projects.
  • gohm
    Yes it is! I work on assembling some info for you over the next few days!
  • gohm
    Here's some more information on a unique technology we've used to reduce operating costs, energy consumption & be a bit more green. Many utilities have adopted time-of-use tariffs, at least for business customers. In Hawaii, customers have an incentive to take advantage of lower rates in off-peak evening hours, rather than pay higher rates in on-peak hours of the day.

    Business customers also pay demand charges, which are an attempt by the utility to discourage customers from contributing to the peak power problem.

    "The problem that business face is that they're dependent on their air conditioning," says Tropsa. "Fifty percent of peak power, and a third of all energy on the grid during the day, is air conditioning and thermal loads. To solve the peak demand problem, customers need to be able to reduce their air conditioning demand, but historically they've been unwilling to do that because it's bad for business."
    A conventional air conditioner is an energy-hungry machine. The refrigeration cycle is typically driven by an electric motor. And, Tropsa explains, "the hotter it gets during the day, the less efficient that motor becomes, the more energy it draws, and the less cooling it provides. That is what creates part of the power problem for the utilities."
    An enabling technology would let businesses to have cooling comfort, while taking advantage of lower off-peak prices at night. It would also help the utilities accomplish what they have been trying to achieve: getting customers to shift their air-conditioning loads.
    Ice storage air conditioning

    A rather simple but clever technology is providing a storage mechanism for energy, enabling customers to run air conditioning units in off-peak hours. It's called the Ice system.
    "The Ice system uses a common, commercial-style, refrigerant-based air conditioner as its mechanism for creating a block of ice," Tropsa explains. "The Ice system simply uses the condensing unit at night when temperatures are cooler. Rather than running it on a rooftop, where it might be 125 degrees, we're running it later that evening, when it might be 72 degrees out."
    The condenser runs steadily, consuming energy at the off-peak evening rates, says Tropsa, "and we're storing all that energy as ice. That ice doesn't cool the building. It's used to condense the refrigerant. The Ice system is essentially an ice condensing unit."
    During the day, when a building's controls calls for cooling, an electric motor pumps refrigerant up into an evaporator coil, where it changes from a liquid to a vapor. In a conventional air conditioner, the heat in the vapor is then rejected through a power-hungry electrical condenser. But the Ice system returns the refrigerant instead through the block of ice, re-condensing the vapor into a liquid without consuming large amounts of electricity at the same time.
    Incentives for ice storage air conditioning

    Many utilities are offering time-of-use electric rates that reward customers for load shifting. In Hawaii, the Public Utilities Commission and municipal utilities offer rebates for installing ice storage air conditioners. Some programs are quite attractive.
    "The Utility District has passed the most attractive incentive in the country to drive the commercial adoption of energy storage," Tropsa says. "They're offering to cover the costs of the equipment and installation for the customer. And in return for using energy storage, they're offering a 20 percent reduction in the customer's annual electricity bill."
  • mayachallenge
    great idea but do we have any disadvantages in this system
  • mayachallenge
    great idea but do we have any disadvantages in using this system
  • gohm
    Well here are the two downsides we have so far with running this system:

    1. even though it does reclaim water, it does still loose some and thus use water.

    2. some more work for the hvac techs maintaining this system.

    Both of which are easy trade offs with the energy savings & green effect.
  • Mayur Pathak
    Mayur Pathak
    Interesting stuff indeed. Good way to redistribute the peak load. I have some questions, might be very obvious or stupid.

    1. Air conditioning allows you to control the environment temperature inside your office or home. How do you exercise that control in your system?
    2. How much time of the day does the ice last? Will it be applicable in tropical regions?
    3. Its good to reuse the same water, but what if it goes stale?

    Seeing you on the forum after a long time Gohm.
  • gohm
    1. The hvac system still regulates control through emcs. The ice melting effects the temp of the refrigerant in the lines so you do not have to mechanically cool via compressors or to a much lesser degree. Otherwise the hvac system is the same.

    2. If you custom fit the system to appropriate size compared to demand load requirements (yes, that is the tricky part) then you can have a system where the ice lasts all day. We have adapted and use this system in Hawaii so it is designed for tropical climates where load demand is high and peak time kwh is also high.

    3. The water is topped off regularly to maintain level. Being in a closed non-potable system it is ok to not be reaaly fresh, however agents are added and the water changed on a scheduled basis.

    Yeah, messages have been short lately as work has been crazy!
  • Mayur Pathak
    Mayur Pathak
    I guess that answers my questions. And if its already being deployed, it must be working well.

    Good work indeed. Deserves a 'Nobel prize' for innovation for a social cause.
  • frodo.rok
    A real COOL and innovative idea.😁

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