Cool as Ice: Solid Solutions to Saving Energy0

From the beaches of California to the bustling streets of New York City, Americans all across the country had one thing in common this summer: they were covered in sweat. From June to August alone, record highs (nearly 2,712) were set or tied in all 50 states, and the National Oceanic and Atmospheric Administration declared July the fourth warmest on record.

Just exactly how hot did it get? A weather station in Southeast Fairbanks County, Alaska hit a high of 97 degrees. Oklahoma City had 51 straight days of 100-degree heat. And most sizzling of all, the city of Morehead, Minnesota was at one point the hottest place on the planet—recording a heat index of 134 degrees Fahrenheit.

While climate scientists were chalking this up to yet another telling sign of global warming, most of America simply turned on the air conditioning and went on with life.

Such a modern indulgence has made living through heat waves more bearable, but places enormous stress on utilities working hard to keep up with demand. In real emergencies, “peaker plants” are used to produce more energy, but these installations are generally expensive, inefficient, and in some cases contribute to even more air pollution.

The Ice Bear cometh

In an effort to avoid future costs for generation and distribution, utilities are turning to an unlikely ally in the fight to keep the grid in balance: ice. For over seven years, Windsor, Colorado-based Ice Energy has sold the “Ice Bear”—a thermal energy storage system that can hook up to existing air conditioning units and effectively cut energy use during peak hours.

We cut source fuel from fossil fuels somewhere around 35 percent.

The units work by freezing 450 gallons of water at night when demand for electricity is low, power is cheap, and the grid is more efficient. Around midday—when peak demand for energy ramps up—the cooling system activates, effectively shutting down a building’s air conditioning system. Coolant is piped through the slowly melting block of ice to an evaporator coil installed inside the building’s HVAC blower system. Once the transition back to water is complete, generally after six hours, the building’s AC system once again takes over.

According to Brian Parsonnet, Chief Technology Officer and Co-Founder of Ice Energy, the Ice Bear offers some big savings for utilities. “For the load that we serve, we cut source fuel from fossil fuels somewhere around 35 percent,” he said in a phone interview. “And the reason the fuel savings are so big is because of the time of day. Everything runs more efficiently at night, including the power plants.”

Leveraging off-peak electricity generation also allows the units to tap into intermittent clean energy sources such as solar and wind. “We enable them dramatically,” said Parsonnet.

“If there was a large penetration of the Ice Bear, it would increase demand for wind by taking an off-peak variable resource and delivering as a firm resource on-peak,” he added. “Texas, California, the East Coast, everywhere—and demand right now for wind is a challenge. In many places, wind is a negative, meaning that there’s too much on the system and they have to pay customers to turn equipment on to use that excess power.”

Sustainable storage solutions

Ice Energy’s modular approach to thermal energy storage is but the latest in a long line of projects using chilled water to defer electricity costs.

In 1999, Stanford University constructed one of the largest ice storage facilities in the world to cool its campus buildings. Each night, the “Ice Plant” freezes four million gallons of water inside a 25-foot-deep tank. Over 360 miles of one-inch steel tubing snake through the ice, decreasing the university’s peak electrical demand by eight megawatts and saving more than $500K annually in electricity costs.

There are no chemicals. They’re virtually 100 percent recyclable. They have an incredibly long life.

More recently, Bank of America in New York City installed 44 eight-foot-diameter CALMAC storage tanks, each capable of holding 1,600 gallons of water and generating a half-million pounds of ice nightly. During the hottest days, the system is estimated to cut the amount of cooling power needed by 50 percent .

While these are custom, large-scale installations, Ice Energy is focused on delivering units that can service the smaller, low-rise structures that make up 95 percent of the buildings in America. Last year, the firm announced a partnership with the Southern California Public Power Authority (SCPPA) to install 6,000 Ice Bears at more than 1,500 sites. To date, over 200 have been installed, which is enough to offset 2MW of peak demand, says Executive Director Bill Carnahan.

“We have over 600,000 hours of run-time on the units and they are performing exceptionally well,” he added.

That likely comes as no surprise to Parsonnet, who says the units function at near 100 percent reliability and are a highlight for any building looking to become more sustainable.

“They’re very green. It’s just water. There are no chemicals. They’re virtually 100 percent recyclable. They have an incredibly long life. We sell them to last 20 – 25 years. If you think about a battery, these are 40 – 45KW hour batteries on a hot day. Think of the amount of chemicals you use in a battery that can deliver 45KW, what its lifespan is, and its limitations. That’s why this is so green.”

Preparing for the ice age

To date, efforts to introduce tax credits at the federal level to help speed adoption of thermal energy storage around the country have fallen flat. Recent bipartisan feuding has paralyzed Washington to the point where states have taken up the reins in developing new stimulus funding.

“As Western governors, we’re working more closely together than any other part of the country,” Washington Governor Chris Gregoire said at August’s National Clean Energy Summit. “We’re building an electric vehicle highway from Canada through California, and our Pacific Coast Collaborative is working to create clean jobs. We’d be very naive to sit back and do nothing with the excuse that we’re in a recession.”

A recent study found that the global market for ice-based thermal energy storage could be close to $100M by 2016 at an annual growth of 25 percent. Falling behind other nations is obviously not a position the U.S. would like to find itself, but in the race to make renewables as cost-competitive and flexible as their conventional counterparts, advancements like the Ice Bear can’t wait for a politician’s blessing.

“If we don’t lead, we will have to trade importing oil for importing clean technology,” said Vice President Joe Biden.“Innovation and energy will go on whether or not we join, and no nation which expects to be a leader of other nations can fall behind.”

Illustration by Owen Gildersleeve