New Thermal Energy Storage System Uses Ice, Not Heat

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Ice-based thermal energy storage systems have a long history dating back to the zero emission, pre-electric days of the ice house. Carbon emissions entered the mix when people figured out how to deploy electricity to turn water into ice. Now the circle has come around again. Renewable energy is beginning to decarbonize ice-based thermal energy storage systems, and the US Department of Energy is here for it.

Thermal Energy Storage Systems, Ice Edition

Much of the attention on thermal energy storage has focused on deploying solar-sourced heat on molten salt, hot oil, specialized bricks, superheated particles, and other materials, but plain water is also coming into its own. The basic idea is to use electricity to make ice in coordination with daily usage cycles, when demand is low. The ice can then be used for cooling during periods of high demand, while avoiding additional strain on the grid.

Saving money on peak electricity costs was the primary goal of conventional demand-sensitive ice based storage systems. They did not necessarily help reduce carbon emissions. Now the falling cost of renewable energy has opened up the opportunity to do both at once.

That’s a significant development because cooling can’t be demand-shifted like other building systems. Utilities can encourage customers to use non-essential systems like EV chargers, dishwashers and laundry machines at off-peak hours, but climate control systems are tied to periods of need.

“Consumers can easily shift some electric loads to off-peak periods, but heat and cooling (HVAC) systems must run at specific times of day when climate control is required,” the Energy Department explains. “HVAC systems are the single largest electrical load for most residential and commercial customers. As a result, they are not able to effectively able to shift their electrical usage and take advantage of TOU [Time-of-Use] pricing.”

The High Tech Ice House Of The Future

The idea seems to be catching on. The energy storage startup Nostromo Energy crossed the CleanTechnica radar last summer, when it announced the installation of its 1.4 megawatt-hour equivalent IceBrick™ thermal storage technology serving two adjacent high profile hotels, the Beverly Hilton and the Waldorf Astoria in California. Nostromo expects the two hotels to halve their cooling costs while reducing their carbon footprints, too.

Nostromo launched IceBrick back in 2018, describing it as “the core element of the most cost-effective, behind the meter, storage system available and consists of plain water and a proprietary nucleate.”

If you caught that thing about proprietary nucleate, that relates to the ability of liquid water to reconfigure itself into a crystalline structure. Nucleates can be used to speed up ice formation, potentially leading to gains in energy efficiency.

Ice nucleation is an extraordinarily complicated topic and CleanTechnica is reaching out to Nostromo to see if their nucleate is something altogether new or if it builds on the existing knowledge base.

Meanwhile, Nostromo explains that its IceBrick system is a space-saver as well as a money saver. That is a significant consideration when building managers are looking at other rooftop carbon-cutting solutions including green roofs, solar arrays, or a combination of the two.

“Weighing only 1,000kg (2,200 lb) and measuring 50x50x400cm (20″x20″x157″) the IceBrick™ is the first ever modular cell that can be installed on rooftops and along exterior walls, taking up minimal amounts of space,” Nostromo explains. “Each cell will be able to store and discharge an amount of energy which is equivalent to 25 kWh of electricity consumed by cooling systems at peak demand hours.”

Nostromo also emphasized safety and cost savings compared to lithium-ion battery packs. “We…have developed a system that will cost half as much as Li-ion systems and won’t be using any rare or poisonous materials,” explained Nostromo founder Yaron Ben Nun.

Next Steps For Ice-Based Thermal Energy Storage: Virtual Power Plants

Ben Nun based his estimate on 2018 figures, and lithium-ion battery costs have generally come down since then. Nevertheless, pushing lithium-ion energy storage costs down to the affordability level for middle- and low-income households remains a huge challenge. The Energy Department has been eyeballing alternative energy storage systems, and ice based thermal energy storage is in the mix.

That explains why Nostromo is among the ice-makers to catch the eye of the Energy Department. Last January, the company reported that the agency is interested in its proposal for installing IceBrick systems in up to 120 buildings over the next three years in California and elsewhere.

The installed energy storage capacity of the project would total the equivalent of up to 100 megawatts. In effect, the project would serve as a demonstration of a widely distributed virtual power plant, in which grid operators organize individual ratepayers into demand-shifting programs with the help of new smart grid communications and monitoring technology.

Nostromo plans to leverage its cloud-based grid integration platform to orchestrate the virtual power plant aspect of the project. To that end, the company also aims to qualify for selling its IceBrick capacity services into utility wholesale markets and community choice aggregators.

As with other systems based on renewable energy and energy efficiency, the IceBrick solution can be installed on an energy-as-a-service model, in which the ratepayer does not have to pay up-front capital costs for installing the new equipment. The energy-as-a-service model typically requires monthly payments that are lower than the ratepayer would see from their utility before the upgrade, resulting in long term savings.

Another Next Step For Ice-Based Energy Storage

In August, Nostromo reported that the Energy Department’s Loan Programs Office has invited the company to proceed with due diligence and negotiation steps on the way to securing a $176 million loan guarantee for the project, under Title 17 of the Clean Energy Loan Guarantee Program.

“The invitation follows the LPO’s review of Nostromo’s part II application and its determination that the project is highly qualified and suitable for a loan guarantee under this program,” the company reported.

Yoram Ashery, the CEO of Nostromo, reports that the company is already seeing “growing interest in the program following implementation of our first US system,” so stay tuned for more on that.

In September the company also won approval from the California Public Utilities Commission to qualify the IceBrick energy storage system as a demand response resource next year.

That quick timeline is of particular note because stand-alone storage systems typically face long interconnection queues before they can hook up to the grid. Nostromo notes that the average wait time is four years in California.

“The IceBrick systems, as dispatchable, supply-side, behind-the-meter thermal energy storage technology, are not subject to these queues and can be online within 6-9 months from contracting with the site owner,” the company explains.

Where’s Congress?

Of course, no news about renewable energy would be complete without a mention of the political situation in the US, where Republican representatives in Congress have been operating virtually in lockstep towards the goal of protecting fossil energy stakeholders at the expense of everyone else.

With Russia forcing another forever war onto Ukraine and Hamas sparking a new conflagration against Israel, Republicans leadership has also demonstrated that it is equally adept at crippling the ability of the US to present itself as a world-dominating economic and military force.

Now would be a good time for Republican Senator Tommy Tuberville to drop that hold on hundreds of military promotions. Maybe the rest of his caucus could also stop futzing around, start working on Schoolhouse Rock-level matters of basic democratic governance, and leave the big decisions up to the grownups.

Here’s hoping.

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Image: IcBrick thermal energy storage system courtesy of Nostromo.