Everything from flywheels to giant batteries have been proposed for utility-scale storage. Utilities in Southern California are going to try ice-powered air conditioners.
The Southern California Public Power Authority, which represents 11 municipal utilities, said on Wednesday that it will use ice storage units from Ice Energy to significantly cut its peak-time energy consumption.
The project will move 53 megawatts' worth of electricity consumption from peak times, typically from noon to 6 at night, to times of lower demand. A large retail store could use about 1 megawatt of power to operate. By shifting energy usage to off-peak times, such as the middle of the night, the utilities hope to reduce costs and improve the reliability of the grid.
Ice Energy's Ice Bear, which stores energy in 450 gallons of iced water, is designed as an add-on to most rooftop commercial air-conditioning units. During peak times, the air conditioner's energy-hungry compressor turns off. The Ice Bear then pumps cold refrigerant to the air conditioner, allowing it to provide cool air but more efficiently.
When temperatures drop at night, the air conditioner's compressor turns on again and converts water back into ice by pumping cold refrigerant through copper coils.
Ice Energy has tested the system with over 20 utilities but the deal with Southern California Public Power Authority is much larger. The rollout will start in the first half of this year and take about two years. "This project includes all of the aspects we look for: managing electrical consumption, improving system efficiency, reducing greenhouse gases, and creating regional jobs for our communities," California Energy Commission Commissioner Jeffrey Byron said in a statement.
Utilities are exploring a number of technologies to reduce energy demand at peak times, including storage and demand-response systems where buildings ratchet down electricity consumption. "Peak shaving" means that utilities can avoid bringing costly and polluting peaker plants online during times of particularly high demand.
Ice Energy originally designed its ice storage system for consumers or small businesses. But it's now marketing to utilities and , customers willing to pay a higher upfront cost for long-term energy savings.