Energy Storage on Ice
Feb 9, 2010 - Collin Sullivan - Scientific American
LOS ANGELES -- Ice Energy has a novel solution for the electricity challenges of the 21st century: Make Popsicles.
Put another way, the company wants to freeze water at night in refrigerator-like boxes adjacent to commercial air conditioners and then thaw it during the day, when power demand is highest. This would theoretically allow AC-hungry commercial buildings in warm climates to cut energy use during heat waves, by shutting air conditioners down while still providing cool air to buildings from melting ice.
After seven years of development and testing, the Windsor, Colo.-based company signed an agreement recently with the Southern California Public Power Authority here to deploy some 6,000 Popsicle-making units at 1,500 locations in the utility's service territory around Los Angeles. Ice Energy says the units, called Ice Bears, will lead to a 30 percent fuel reduction for the utility through avoided use of so-called peaker generation plants, which are only turned on when demand is highest.
In Southern California and other warm places, the benefits are numerous, the company says, because of a heavy reliance on air conditioners during hotter months. Avoiding peak power also means importing less coal-fired electricity from out of state when the California grid is taxed during heat waves.
"Electricity suffers from the central tenet that it has to be used when it is generated," Ice Energy CEO Frank Ramirez said in an interview. "What we're really leveraging is what nature gives us every single day through its rotation: cooler temperatures at night."
Ramirez likes to call their technology "energy storage," but in truth the Ice Bear is just a way to use energy when it is cheaper and more plentiful. Doing so could save utilities money, reduce greenhouse gas emissions and create more blue-collar jobs for HVAC technicians and manufacturers.
The cost? The Southern California Public Power Authority paid about $100 million for the 6,000 units, a price that comes with a maintenance guarantee by Ice Energy, which plans to subcontract to HVAC experts, and smart-grid coordination with the distribution network.
That may seem pricey on its surface, but Ramirez insists the investment will save the utility as much as 20 percent in reduced fuel costs over a 20-year period. And, as he likes to point out, that is an investment not backed by the federal or state government, unlike many rival new technologies that tend to vie for subsidies.
"We are the first stand-alone energy efficiency technology that doesn't require government assistance or subsidy to employ," Ramirez said.
Not your average icemaker
This is how the Ice Bear works: It fluctuates between charging and cooling, freezing 450 gallons of water at night (a process that might be said to "store" electricity) to then reverse course during the day. The cool air is fed into buildings with the same duct system already in place.
Some have likened the technology to hybrid cars, which rely on batteries to shut down internal combustion engines until their juice runs out, when the engine restarts. Also comparable are geothermal heat pumps that are used widely in Scandinavia and other cold nations to heat homes during colder months. Like the Ice Bear, such systems act like freezers, in a sense, with the back of the pump (which gives off heat) built into the inside of a home, with water freezing taking place outside.
"In Norway almost all new homes are heated by heat pumps built into the wall, with the 'back of the freezer' on the inside of the home and the 'freezer' on the outside of the home," said Gunderson, a Norwegian national. "A home freezer is a typical heat pump, and the cheapest way to heat your home is to fill the freezer with water, then when the water is in the form of ice, throw out the block of ice outside of your house, then fill the freezer with water again."
Ice Energy seems intent on capitalizing on the same sort of simple system in the inverse, and Ramirez readily admits his technology applies best to warm climates. Energy is lost in the conversion process from ice back to water (as much as 15 percent), but Ramirez said a temperature gradient of 15 degrees Fahrenheit or more from day to night makes the product energy neutral.
"In most of California, the average gradient [the difference between day and night temperatures] is 22 degrees," Ramirez said. "We have a natural advantage provided by cooler temperatures to reject heat, instead of running the AC that has to overcome heat during the day."
As for water supply, the Ice Bear is filled once and never filled again. And Ramirez insists the concept is storage by any other name, just not the kind of storage people tend to anticipate.
"It's a battery filled with water," Ramirez said, taking up the hybrid-car analogy. "I think you can draw the conclusion that nothing will ever be cheaper as a storage medium."
Visit to Capitol Hill
Ramirez said California is an ideal venue for bring his Ice Bears to market for another reason: The state has on the books a renewable portfolio standard of 20 percent by 2010 and to 33 percent by 2020.
Citing a report on wind power by the North American Electric Reliability Corporation, Ramirez said what nobody wants to admit in California that an intermittent source like wind tends to be weakest during peak power periods. When it is hottest, in other words, the wind tends not to blow as hard.
This would make wind an unreliable source during hot, windless days when some sort of storage medium might counteract that reality. "The greatest output of wind occurs 180 degrees out of phase with the peak," Ramirez said. "It's variable in nature and typically blows when you don't need it."
So to this executive, the answer is pairing ice storage with renewables as complementary technologies. He also said the distributed nature of his machines means less loss of electricity through transmission and distribution, in addition to more reliance on baseload power, which is more efficient than peaking power.
"Air conditioning demand is the root cause of the peaking power problem," Ramirez said, noting that 14 peaking units have been stymied recently in Southern California by environmental justice activists who do not want the plants built in low-income neighborhoods.
At least one prominent lawmaker, House Speaker Nancy Pelosi (D-Calif.), has become a believer. Pelosi recently invited Ramirez to address the House Democratic caucus, where he gave Democrats much the same pitch he presented to this reporter.
Up next? Ramirez said he is talking to the Los Angeles Department of Water and Power -- the largest public utility in the United States -- about signing a deal that could potentially dwarf the Southern California Public Power Authority arrangement. On the table in those discussions is building a manufacturing facility in Southern California, which is a high priority for a state facing 12 percent unemployment.
"We are going to be speaking to [Los Angeles Mayor Antonio Villaraigosa] and the L.A. Department of Water and Power about what it might take to build a plant in Southern California," said Ramirez, adding that if Ice Energy gets a big enough project commitment from the utility, a California-based plant is possible.