Clean renewable energy requires power storage in batteries. The lithium-ion battery is the most efficient one. The technology is also expensive which limits their impact in developing countries. An innovation by a US energy company might change that. NantEnergy is developing a zinc-air battery that is considerably cheaper than other battery types currently on the market. Compared to lithium-ion battery costs estimated to be between $300 and $400 per kilowatt-hour, the zinc-air battery has cut cost down to less than $100 per kilowatt-hour.