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“Ice battery” air-con technology set to cool Australian homes – and peak power demand

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One Step Off The Grid

US-made thermal “ice battery” energy storage technology that could dramatically change the way people cool their homes in summer – potentially cutting household peak power consumption by up to 95 per cent – is poised to take on the Australian market, through a distribution deal with local solar hot water company Apricus.

Ice-Energy

California-based Ice Energy inked an agreement, in June, making the Melbourne-based Apricus the exclusive distributor of all its thermal energy storage products in Australia, covering all market segments, including utilities, commercial and industrial, and residential.

The company is best-known for its commercial and industrial Ice Bear technology, which works alongside air conditioning units by freezing water at off-peak periods, or when excess solar or wind power is available, and using the “ice battery” to provide power-free cooling during on-peak periods.

More recently, however, the company has been attracting attention for the creation of its “Ice Cub,” a smaller-scale version of the Ice Bear, that is targeting the potentially huge residential market.

Unlike the Ice Bear, the Ice Cub is a kind of all-in-one, hybrid battery/air-con unit, that replaces the conventional home air conditioner.

But unlike conventional air-conditioners, the Ice Cub has the ability to fill an insulated tank with ice in four hours, store it, and then, on command, switch from conventional AC to using the ice to cool the house for at least three hours, instead of electricity.

As Greentech Media pointed out in this article last year, “that’s a big deal” – both for households, and potentially utilities, considering it can essentially eliminate three hours of peak demand for cooling, which is the largest single household use for electricity, and a huge source of demand for power generators.

It is particularly promising for households with rooftop solar, who can use excess solar generation to make the ice – rather than sending it back to the grid – which can then be used for cooling as the sun goes down and as families return from work to their sun-baked homes.

The system also comes with a 20-year warranty, and – unlike most conventional lithium-ion and lead acid batteries – does not degrade over time.

“We guarantee we’ll make the same amount of ice,” said Ice energy CEO Mike Hopkins. “It’s a tank of water and it freezes; it doesn’t freeze less over 20 years.”

For the Australian market, the products will initially be imported from the US – Hopkins says the company has production facilities in New York state that can make 1,000 Ice Cubs a month.

But the “mutual intent” of both parties, through the Australian distribution deal, is for Apricus to manufacture locally as sales increase. A key early market will be new-build homes and existing homes looking to replace their cooling systems.

“We’re delighted to be partnering with Apricus in this new market for Ice Energy,” said Hopkins, in a statement in June.

“Over the last 12 months we’ve had a steadily growing number of inquiries from Australia about our products. This is not surprising, given the needs of the country’s grid, the importance of their cooling load, and the ability of our products to turn that load into a cost-effective and reliable storage resource capable of flattening peak demand and eliminating solar over-generation.”

Chris Taylor, Director of Apricus Australia, said his company shared Ice Energy’s enthusiasm about the partnership, and the products’ potential in the Australian market.

“There are terrific applications for the whole product line, but the hybrid AC/energy storage system for the home, with its ability to provide cooling 24/7, make ice with excess solar generation and cool for four hours without needing electricity to create the cooling for that period, is a truly disruptive product tailor-made for Australia,” Taylor said.

This article was originally published on RenewEconomy’s sister site, One Step Off The Grid, which focuses on customer experience with distributed generation. To sign up to One Step’s free weekly newsletter, please click here.  

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  • George Darroch

    This is a crucial technology, and it’s surprising it hasn’t reached adoption here sooner. It partners perfectly with solar energy, and should be widespread within a few years, if it’s priced correctly.

    I’m interested to know what their system cost and round-trip efficiency is, and how this compares to a battery with airconditioning. (Given that a battery has greater versatility, I can see this being more attractive in the more tropical parts of the country)

  • Brunel

    Is it mandatory for new houses in Vic to have ducted gas heating?

    • Warwick Haar

      no they are not

      • Brunel

        I hope you are correct. But the rumour persists among grandpas!

    • Alastair Leith

      Hope not!

      Fig 3.20 from the BZE Buildings Plan: Heat pump (with a COP of 4.5) is 13x more energy efficient that a ten year old ducted heating system.
      https://uploads.disquscdn.com/images/f4e137344b17072a5cef7c16f6197771a23700bb370156f282b983f71493d218.png

      • Brunel

        Brilliant graphic! I wonder where it is from.

        I know that heat pumps are magical but the politicians are stupid and against having a free market in housing and heating!

        • Alastair Leith

          I designed it based on a standard Sankey graph by one of the researchers on the Buildings Plan, either Richard Keech or Tim Forcey IIRC. I think it was Richard. There was some internal debate about which was better, which do you think communicates the info better?

          https://uploads.disquscdn.com/images/d1fd8a78056b065b3360994f491591aba1c61e85acf15d0fed547fa1e9599798.png

          • Brunel

            The earlier one you uploaded at 353pm UTC with red arrows. The one I replied “brilliant graphic” to.

          • Alastair Leith

            Yeah that was the one I was talking about. I designed the BZE Buildings Plan publication and made and/or supervised all of the graph design in it. Its from that publication (free download or hard copy reduced to $20 I think these days). LINK

          • Brunel

            Well done mate.

  • Tom

    About 25 years ago when I was in high school I did a couple of weeks of “work experience” with ETSA (as it was then known) in Adelaide.

    One day we went down to Flaxley in the Adelaide Hills to a dairy, where they were trialling something similar. The dairy had a big water tank (probably 10,000 gallons) with refrigeration tubes running through it at about 20cm spacings. At night time the refrigeration would turn on, freezing the tank of water, and during the day when the cows were milked the cold water would cool the milk from cow body temperature down to a few degrees above freezing so that the storage vat didn’t have to use as much daytime electricity.

    I looked inside the tank – there was a lot of water still, with about 2 or 3cm of ice around all the pipes. Similar to a beer tap in a busy pub on a humid day. This would make sense though – you don’t want the whole tank to freeze or you would burst the tank, and probably the refrigeration pipes inside it too!

    I’m thinking you’d need a pretty big tank though. Good for a bungalow on a block, not so good for a townhouse or an apartment in the sky.

    PS – this is great news – it will give the coal generators something to do at night so they don’t have to struggle to turn themselves off!

    • Mike Westerman

      Ice storage systems have been around for a long time – I was on a project in more than 20y ago to remove the one at Royal Brisbane Hospital! Those systems used plastic balls filled with water in a tank of glycol and water. The low COP and high maintenance costs killed them back then.

      This Ice Cub and its big brother ICE Bear may fair better – it’s hard to work out what the COP is during ice production: the CB rating required is 12kW, so the compressor power draw is less than that. It stores 240,000 BTU or 70kWh in 6h (70 liters) which is about 11.7kWht so the COP is at least 1 or better. If the starting current that would trip the CB is 3x running current, the COP would be about 3. As an airconditioner it has an SEER of 18, which suggests a COP of 5.2 but not clear if this is for ice production.

      Thermal storage is going to be a thing once RE penetration becomes significant, as it is much cheaper than batteries. I can see the size of HW systems increasing significantly, and installation of ice or chilled water systems for cooling becoming commonplace, so good to see a commercial product available, but horrifying that it continues the use of high GHG potential R410A – why not CO2?

      • Alastair Leith

        Because the owners of commercial refrigerant IP are the same people who make the appliances and can charge a lot more money than you can for CO2? Adam Smith’s invisible hand in your back pocket once again.

  • Miles Harding

    It just goes to show there’s no substitute for good design!

    In a yacht or 4WD, this makes sense and is called a ‘Eutectic refrigerator’. It’s far more effective that the more typical Engel and WAECO types seen around.

    The use of this in a house is indicative of bad design in the first place. Insulation and thermal capacity (AKA bricks inside the envelope) can achieve the same thing passively, only requiring a very small air conditioner that may be rarely used at all.

    Points for trying, but they’re solving the wrong problem.

    • Mike Westerman

      I would anticipate eutectic storage for fridges and freezers at home as well should be part of the “reserve” for intermittent generation. But I wouldn’t write off ice storage entirely – thermal inertia and insulation are well and good in non-humid climates, but outside air requirements mean in humid areas ac is more often needed and thermal storage can play its part.

    • MaxG

      3rd paragraph = spot on! My thinking exactly… but this is business for you; make a dollar out a problem; and the best problems to solve are those were you do not remove the root cause, but keep band aiding the issue. — A funny world we live in.

      • Mike Westerman

        Heh you guys probably don’t try and sleep in 28deg 95% RH but you need to have fresh air and need to reduce humidity under those conditions – there’s a point in the tropics where a fan doesn’t make for a good night’s sleep. Ditto in an office where wind precludes open windows, and equipment loads need to be removed. OA is humid and needs drying. That’s 30kJ/kg of OA to reach design indoor conditions of 25deg 50% RH

      • Miles Harding

        As a bit of added silliness:
        For many PV households, there is plenty of power available during the heat of the summer days, so an aircondioner is perfectly matched, whereas the icemaker is intended to be run at night (from cheap coal power).

        I’ll take one of the points for trying back!

  • Ian

    We guarantee we’ll make the same amount of ice,” said Ice energy CEO Mike Hopkins. “It’s a tank of water and it freezes; it doesn’t freeze less over 20 years.”

    Very cute, but the problem with air conditioners is rust and wear.

    As Miles Harding says. ‘Insulation and thermal capacity’. Get the basics right then look to solutions like this one. Cost is king. This type of idea will have to compete with 1. Precooling a well insulated house with large internal thermal mass. 2. Solar power plus battery storage.

    The best place to put cold( and/or hot) thermal storage is in the house, that way any leakage of the stored product will benefit the living space it is supposed to cool( or heat. This should spur some lateral thinking of products that can combine internal thermal mass with active cooling elements. Here are some free ideas: hydronic heating or cooling of large thermal mass walls floors or stone furniture. Novelty ice sculptures, ” iceplaces” instead of fireplaces.

  • MaxG

    On that note: I stuck a data logger into the neighbour’s house to record inside temperature and humidity. When comparing the data to my home I am building, it turns out that my house performs better then his standard 20yo house. However, the kicker is: my house has no ceiling, and 70m² opening from the veranda… and the cladding above windows and the eaves aren’t done either.
    At some point during the night the temperature dropped to -1, the neighbour ended up with 5 degrees, while mine did not drop below 7 °C
    What a shocker… but there is the problem or bad performance… no post insulation will fix this problem.
    My point: you can stick any heating or cooling system into 99% of AU houses, which will leave the house as quickly as you turn it off. 🙂

  • Bill Holliday

    Water energy storage of warmth or “coolth” has got to be vastly cheaper than battery energy storage. However there may a couple of small problems.

    [1] How easily does heat or “coolth” travel through ice encrusting the pipes (what is the thermal conductivity of ice) as there is no chance of convective or radiative coolth transfer to the piping which comprises the output (and input) mechanism of the system?

    [2] Solar energy is greatest in summer when this cooling is required because of the increased length of a day and the higher sun angle through the day and this is when solar energy can directly power an air conditioner – no storage required – and cool down the house’s thermal mass. At night outside temperatures drop, making the heat gain through the house insulation less and the making the job of the thermal mass easier.

    Storage of “coolth” is already common. Many commercial fishing boats use concentrated brine solutions (which don’t freeze until they get down to -21C (NaCl brine), other brines get down to almost -50 C). This means that circulating pumps can increase the coolth output for a given length of piping.

    Storage of heat in water in winter is even more advantageous as the operating temperature range extends to 100C. For a desired room temperature of 20C this is 100 – 20 = 80 C temperature difference rather than 20 – 0 = 20 C for water ice. I know I have been banging on about this for years in these columns (one day i will build one!) Just remember that for an operating range of 90 C down to 45 C, water will store 52 kWh in 1000litres. That’s about $31,000 worth of Powerwall.

    • solarguy

      I heat or cool my home during the day with PV and charge a battery bank to do the same again at night. Plus I send power back to the grid most days lately for a profit. That’s right I mostly don’t bring in any power from the grid, I’ve beaten the bastards at there own game. LOL!

    • Tom

      What you say about the energy contained in hot water and in cold water is true, but remember that ice contains the equivalent of 79 degrees latent energy.

      So if 1000L was 50% ice (500L of ice), and was heated from 0 degrees to 5 degrees (by which time it has all melted), then this is the equivalent of heating the 500L of water by 5 degrees and the 500L of ice by 84 degrees, so heating the whole lot by 44.5 degrees.

      This is the same 52kWh of stored cooling power as in your 1000L hot water tank described above.

      • Alastair Leith

        >> but remember that ice contains the equivalent of 79 degrees latent energy.

        it does? how does that work? Does this relate in any way with the fact that ice forms quicker from warm water than very cold water (something to do with phase change anomaly of water and perhaps a fourth phase as some have speculated of EZ water).

        • Mike Westerman

          I think this refers to latent heat of fusion for water which is 334 kJ/kg so 79x the specific heat (4.2kJ/kg/degC) but a weird way of thinking about it. Latent is so called because the temperature doesn’t change during freezing.

        • Tom

          If you take 1kg of ice which has a temperature of negative 1 degree, and bathe it in 1kg of water which has a temperature of 81 degrees, then the ice will melt and you will end up with 2kg of water which has a temperature of positive 1 degree.

          In the ice box this means that the cold water will remain at about 1 degree until all the ice has melted, and then it will heat up much more quickly once the ice has melted.

          Let’s say there was 400L in the ice box and it froze up so that 200L was ice and 200L was water, and if water was coming into the heat exchanger in the ice box at 21 degrees and exiting the ice box at 1 degree. Then 80*200/20 = 800 litres of warm water would run through the heat exchanger before all the ice melted, and this would only heat up the tank by 1 degree to 2 degrees. However, once all the ice has melted, only 400/20 = 20 litres of warm water would be required to run through the heat exchanger to warm the tank up from 2 degrees to 3 degrees, and 20 litres to heat it up from 3 degrees to 4 degrees, etc.

          • Alastair Leith

            Thanks for explaining the calculation, Tom. So is this essentially because there is additional the energy required for the phase change from a solid to liquid for water? Is there energy required the other way or does it release energy the other way?

            More and more questions, i looked on chemistry stack overflow but not getting the answer yet!

          • Tom

            Exactly.

            You need lots of energy to change ice to water, and you need even more energy to turn water into steam.

            The easiest way to think of water to steam – imagine putting a saucepan of water onto a hot plate. The energy of the hot plate is being absorbed into the water as it heats the water. Imagine how long it takes to boil the water. Now imagine how long it takes for the saucepan, once boiling, to boil dry. The water is only warming from 99 degrees (liquid) to 101 degrees (gas/ vapour), but it takes much longer to achieve this two-degree rise in temperature than it takes to achieve the first 80-degree rise.

            The reverse happens in a tropical cyclone – water vapour condenses into liquid water, releases a lot of heat, hot air rises and therefore cools, more water vapour condenses as the higher altitude air has cooled – releasing more energy, and so on. That’s why cyclones lose ferocity as they cross over land – not enough water vapour lifting from the warm ocean to keep providing the energy.

            Air-conditioners are cooling a house, so they’re taking energy out of the house. The energy in this ice-bath design would be absorbed from inside the house (presumably by a fan blowing air over pipes that are cooled by flowing cold liquid), then the liquid warms up close to the room temperature of the inside of the house, then the liquid is pumped outside the house taking the house’s heat energy with it, and then the liquid transmits this heat energy to the ice bath, where some of the ice will absorb the heat energy and turn into water. The liquid leaves the ice bath with little energy so that it has the capacity to absorb more from inside the house.

          • Alastair Leith

            Thanks for your patience in explaining some more, Tom!

          • Alastair Leith
  • Ren Stimpy

    Is the ice under pressure?

  • Ben Davies

    It’s a nice idea and i hope it is successful.

    I don’t fully understand all about COPs etc but would there be a disadvantage to making ice during the heat of an Australian day (i.e. lower COP) than cooling the house during a cooler night (i.e. higher COP) with cooler nights inland and non-tropical regions anyway? I know the point of this whole system is all about using your own rooftop solar and not ‘giving’ it away to the grid.

    I went round a solar farm at Darwin Airport once and they had a second stage planned along with battery storage to power the aircon at night. When I asked them about using ice as storage they did not respond.

    Having just been on a quick trip home to inland NSW from Darwin I was struck by the sense on storing heat from excess daytime solar in my rainwater tank for use at night and during cloudy days. I reckoned there was about 150kWh of heat that could be stored there. How quickly it would cool down i did not do the calculations for that.

    • Mike Westerman

      Ben if space is not an issue (as it generally isn’t for airports and universities), then chilled water storage may be a better solution with higher COP, lower losses and cheaper storage and production. It’s certainly much cheaper than batteries!

  • JohnRD

    Using water/ice as the phase change material for storing cold for air conditioning is a lot less efficient than using an appropriate phase change material with a phase change temperature closer to target temperature. (Energy required using a heat pump varies with temperature difference squared.) See: http://pragmatusj.blogspot.com.au/2012/08/phase-change-materials-background.html