Right now, in the U.S., the answer would be Tesla. Out of a 3,000-acre facility on the outskirts of Reno, Nevada, Elon Musk's Gigafactory will, by next year, be churning out 35 gigawatt-hours per year of lithium-ion batteries for both EVs and stationary structures like homes and businesses. Musk is hinting at building three more such factories. The Tesla Gigafactory is designed to supply enough batteries to meet the demand created by Tesla vehicles, but for other EV manufacturers, the supply chain between battery production and vehicle is not as clear. "Everybody else is focused on doing the whole car–we're just doing battery packs." [Photo: courtesy Romeo Power] With the EV industry set to be valued at $32 billion by 2020, and with EV batteries on track to become a $240 billion industry in the next 20 years, Romeo Power, an energy storage company founded around a year and a half ago in the greater Los Angeles area, is looking to give Tesla some competition.