A Santa Barbara-based company called Ice Energy has partnered with NRG Energy to deliver 1,800 “ice batteries” to commercial and industrial buildings served by electric utility Southern California Edison (SCE). The units are expected to reduce air conditioning bills by up to 40 percent and eliminate 200,000 tons of CO2 over the next 20 years.
Ice Energy has been building ice-based cooling systems since the early 2000s. Much like pumped storage or compressed air “batteries,” Ice Energy essentially stores electricity by drawing power from the grid at non-peak times to freeze water in a special container. Then at peak times, when the cost of electricity is high and grid operators are struggling to keep up with demand, Ice Energy’s systems kick in and use that block of ice to cool the space that the air conditioning unit normally serves.
Although the system isn’t storing energy like a lithium-ion battery does, it draws energy to “charge” and replaces the energy that would be needed to run an AC unit when it “discharges.” That’s good for the environment because air conditioning compressors are energy-intensive, and when a city like Los Angeles suffers a heat wave, people tend to run their ACs more. Grid operators have to meet that demand, and, to do that, they’ll often turn to fossil fuel-burning additions like natural gas peaker plants, which can be brought online relatively quickly. But if local, behind-the-grid energy-storage systems can meet the additional needs of a home or business before they have to turn to the grid, that reduces the demand that grid operators would otherwise have to meet.
Sort of like your grandparents’ ice box
In a phone call with Ars, Ice Energy CEO Mike Hopkins said that SCE agreed in April to purchase the 1,800 units, called IceBear 30s, and to cover the cost of installation. Hopkins wouldn’t say how much the SCE is putting down in the deal. There are also some strings attached: although IceBears can be added onto many existing air conditioning units, SCE is looking for commercial and industrial candidates who will be willing to replace aging HVAC systems with something more energy-efficient (SCE is also offering discounts on upgraded HVAC systems that would be installed with the IceBear units).
What the utility gets in exchange for its discounts is control over when the IceBears are turned on and off at each commercial or industrial property. Each IceBear 30 is capable of replacing a 10-ton AC unit for three hours, Hopkins said, and SCE will engage the IceBears on the roofs of its customers when it needs to lessen its load for three hours. SCE could do this, for example, on a hot afternoon in July.
SCE won’t be turning on or off the IceBears individually but will dispatch the cool air in groups. “While they [SCE] could look at individual IceBear units, the system is really designed for megawatt-scale resource control,” Hopkins said. “They’ll see them on an aggregate basis.”
SCE’s willingness to buy into this storage scheme has political roots. In 2013, California mandated that the three largest utilities serving the state add a collective 1.3 GW of storage to the grid by the end of the decade in a way that meets peak demand in a cost-effective way. The deal with Ice Energy and NRG is part of Edison’s own commitment to add diverse kinds of energy storage to the grid. The utility has also purchased more traditional batteries from Tesla. “The Ice Bears will provide a total of up to 25.6 MW of peak storage capacity to SCE under 20-year Power Purchase Agreements (PPA),” a press release from Ice Energy said.
The project was a long time coming, too. Hopkins said that SCE’s commitment to buy storage has “been hung up… by appeals, mostly regarding a gas peaking power plant. It was only within the last month that we were cleared of this regulatory delay.” This is also the world’s largest ice storage deal to date. Ice Energy inked a deal in 2010 with the Southern California Public Power Authority (SCPPA) to deploy up to 1,500 IceBear units in Southern California. But Hopkins said the economic conditions weren’t right yet.
“That project actually never proceeded,” the CEO said. “The contract… was a real surprise to everybody because no one had entered into a contract that big for energy storage. The city of Glendale ordered 2MW, and then the contract just kind of sat there, which I think is a reflection of the fact that back in 2010… utilities just weren’t ordering storage. Starting in 2013, when the state of California mandated storage, the world had obviously changed.”
In 2015, Ice Energy partnered with Riverside Public Utilities (RPU) in California to install 5MW of capacity on commercial buildings over five years. The utility stipulated that it would be allowed to cancel the contract if the Ice Bears didn’t meet expectations. Four units were just installed on top of California Baptist University.
Ice Energy has also just launched a residential product, which will go into production in the summer. The company has contracted again with SCPPA to offer 1MW of residential storage—approximately 100 IceBear 20s—which are smaller than the IceBear 30s SCE is procuring for commercial and industrial buildings. Hopkins also said that Ice Energy is still working out a similar deal to subsidize residential IceBears with a Massachusetts power company, which he declined to name because the deal wasn’t finalized yet. Eventually, Ice Energy hopes to sell its product through retail channels as well as through power companies.
“The residential product was designed to function ideally with solar,” Hopkins explained. “If you’re restricted in net metering… our home system can actually make its ice in four hours, you would use your solar over-gen [over-generation] to make ice” and eliminate the peak hours of AC in the afternoon and evening.
An even smaller unit, the IceBear 10 (also known as the Ice Cub), can serve as a heat pump and run in reverse during cold periods. The Cub would heat your home with electrical heating, which is probably not a practical option if you live in an area of the US that needs heating throughout the winter.
For now, Ice Energy doesn’t seem to have many competitors in thermal energy storage. A company called Axiom freezes salt water during off-peak hours to provide refrigeration during peak hours. (Ice Energy says it’s working on that, too, by developing a system that uses glycol as an additive instead of pure water, as the IceBears do.)
But the concept has been around for a long time: see this PG&E explainer from 1997 (PDF). Cost has been a major stumbling block to adoption, and Ice Energy doesn’t post any cost-related numbers on its site. (For residential systems, the company notes that access to clean energy incentives from state and federal governments “can reduce the cost of a home IceBear to the point that it is no more than, or even less than a conventional home AC unit.”) The efficiency of the system also depends on where you are in the country: in a post on Altenergy Mag from 2016, Hopkins wrote that “Ice Bears are most efficient in areas where nights are significantly cooler than days.”
For now, Ice Energy seems to be solving the cost and efficiency problems by selectively partnering with utilities in regions that get a lot of heat. And whether or not ice-based systems take off, the idea of deferring energy use with ice is certainly cool.
Listing image by Ice Energy