How small batteries are helping one NYC business cut energy costs

A food company in New York City, Wonder, has cut its energy costs by about $20,000 over six months by installing small plug-in batteries at 21 of its locations. The batteries, each about the size of a suitcase, were supplied for free by David Energy, a retail energy provider. Wonder says the savings amount to roughly 3% to 5% of its energy costs at those sites.

The batteries work by storing power and releasing it during the times electricity costs the most, a process called peak shaving. Each unit holds 2 kilowatts of power and 6 kilowatt-hours of energy, and they're grouped into sets of three that plug into a dedicated circuit, similar to plugging in a large appliance. David Energy's software predicts when prices will spike and automatically discharges the batteries at those moments. The company also enrolls customers in utility demand-response programs, which pay businesses to reduce their grid use during periods of high demand, such as heat waves.

This system was built for commercial buildings between 500 and 10,000 square feet, not homes, and David Energy says it isn't pursuing larger installations right now. Still, it points to a broader trend: battery storage that's small, relatively cheap to install, and doesn't require the permits or roof space that bigger systems need. The batteries use lithium iron phosphate chemistry, which carries lower fire risk than other lithium batteries. As this kind of plug-in storage becomes more common in commercial settings, similar compact options may eventually reach the residential market.