That's a Tesla superfan (which apparently is a thing) posing in front of the company's new Powerwall battery, which Elon Musk unveiled today. Meant for homes and businesses, the battery will allow users to store energy from their solar panels, windmills, or whatever else they're using to charge up their cars and power their homes without any help from the grid. Chris Mooney explains why this could be a really big deal as we head toward our promising future of distributed energy.