How small, distributed batteries could help the power grid

Installing a large energy storage battery in a city like New York has become a regulatory ordeal. Population density, the tangle of rules and, above all, the fear — relatively rare but highly publicized — of battery fires have generated neighborhood resistance to large-scale storage projects, even as these utility-scale installations multiply rapidly in the rest of the world. That clash between the need for more storage and local opposition is the starting point for a trend that is beginning to take shape: instead of fighting for centralized megaprojects, several startups are putting much smaller batteries in everyday and unexpected places, from induction stoves to street food carts.

The underlying idea, expressed by David Hammer, co-founder of PopWheels, at a New York Climate Week event held on September 24, is that the biggest obstacle for centralized storage is that its benefits are abstract to people, while its costs are very concrete. These companies' answer is to spread storage capacity across small units tied to a direct, tangible use for the user: savings on the bill, resilience against blackouts or less pollution.

PopWheels is the most developed example of this approach. The company operates a battery-swapping system for delivery workers who move around the city on electric bikes: instead of stopping to charge, riders swap their depleted battery for a charged one at one of the cabinets distributed across the city. According to Hammer, there are already some 50 of those cabinets and around 2,500 batteries in circulation. The company has recently begun offering its batteries to food cart operators as well, who have traditionally relied on gasoline generators. Four of its batteries combined supply about 5 kilowatt-hours, enough to cover roughly a day of operation for many of these businesses, allowing a polluting generator to be replaced with stored energy.

Other companies are bringing the battery directly inside homes. Copper makes induction stoves with built-in batteries: the appliance makes it possible to keep cooking during a power cut and, by supplying part of the energy needed at the moment of use, can spare the owner a costly upgrade to the home's electrical system. As Sam Calisch, co-founder and chief executive of Copper, sums it up, it is not just about selling resilience against blackouts, but cost savings outright.

In a related space, companies such as Every Electric and David Energy sell plug-in batteries for homes and businesses. Every's offering consists of a battery designed to be connected to an air conditioning unit: the company supplies the equipment and pays customers to cut their consumption at moments of greatest strain on the grid. David Energy follows a similar model, but aimed at businesses such as laundromats, garages and gyms. James McGinniss, co-founder and chief executive of David Energy, goes so far as to call this movement the most important thing to happen to the grid sector in the last twenty years.

A feature common to all these solutions is that, being small or built into another appliance, they generally require no grid upgrades or lengthy permitting processes: you just plug them in. The article compares this model to the rise of so-called "balcony solar," small solar modules that plug in directly and help offset a home's or business's energy demand without complex paperwork.

The sum of all these individual units, modest as they are on their own, could represent a meaningful change for the grid as a whole. Calisch calculates that if every stove sold in the United States included a battery, the aggregate capacity would reach tens of gigawatts: a reserve that could be aggregated and activated precisely when the grid is under stress.

The piece is clear, however, that this trend does not remove the need for large-scale storage: bigger battery installations will remain essential to back up intermittent renewable sources such as wind and solar, in a context of rapidly growing electricity demand. What the article raises is more of an open question: to what extent can a massive, decentralized sum of batteries in bikes, stoves and air conditioners ease the pressure on increasingly congested grids, especially in dense cities like New York, where any resource that helps avoid summer blackouts is welcome.

Overall, the piece — written by Casey Crownhart and published as part of MIT Technology Review's weekly climate newsletter The Spark — portrays a change of strategy: instead of trying to overcome social and regulatory resistance to big batteries, several companies are choosing to go around the obstacle, distributing storage across thousands of small points, each justified by an immediate, personal benefit for whoever uses it, and trusting that the sum of those small pieces will end up having a large effect on grid stability.