Batteries are undergoing rapid advances. For example, modern zinc-air batteries have the remarkable ability to use oxygen as energy—but that oxygen isn't stored in the battery itself. Zinc-air batteries take in surrounding oxygen to undergo a reaction to discharge energy called the oxygen reduction reaction (ORR). While this convenient strategy is promising, the slow speed of the ORR limits the practicality of these batteries.

When they get home, the residents of a small housing association on the outskirts of Hudiksvall, Sweden, plug in their electric vehicles to charge them or, intriguingly, power their homes.