And after all, it's a Powerwall

Electric car pioneer Tesla has unveiled a "home battery" which its founder Elon Musk said would help change the "entire energy infrastructure of the world." The Tesla Powerwall can store power from solar panels, from the electricity grid at night when it is typically cheaper, and provide a secure backup in the case of a power outage. In theory the device, which typically would fit on the wall of a garage or inside a house, could make solar-powered homes completely independent of the traditional energy grid. "The goal is complete transformation of the entire energy infrastructure of the world, to completely sustainable zero carbon," Musk told reporters shortly before unveiling the Powerwall in a stylish warehouse space outside Los Angeles yesterday. Initially the device, which will cost US$3,500, will go on sale in the United States later this year. But the aim is to roll it out internationally some time next year. Germany is seen as a key market for the product - which is about 15 cm (6 inches) thick, 1.2 m (4 feet) tall, and 90 cm (3 feet) across - because it has among the highest take-up of solar energy in the world. But it could also be a huge boon for under-developed regions, where power is often unreliable at best, despite abundant solar energy - and Musk compared the potential to that of the way cellphone technology has expanded. "It's analogous to the way mobile leap-frogged landlines," Musk said, adding "this is going to be really great for the poorest communities in the world - this allows you to be completely off grid." Musk stressed however that moving advanced economies like America away from unsustainable fossil fuels was a key goal. However, the Tesla chief was coy when asked whether Tesla Energy would be a bigger business than Tesla Motors, for which he is best known. He dodged the question. Personally, I don't care which one comes out the bigger one, because they are both on the same page about the fact that we don't need fossil fuels - we have this handy fusion reactor in the sky, called the sun. If everyone was on the same page, there would still be hope for our planet. But as far as winning the Premier League title goes, there is no hope for Manchester United, or for that matter, any team other than Arsenal. Chelsea are at the top of the table with four games to go. Second is Manchester City, who are 13 points behind with four games to go. Third is Arsenal, who are also 13 points behind (the tie is broken with City winning on goal difference) but they have five games to go, as do Sunderland (who are in the drop zone along with QPR and Burnley). The only way someone other than Chelsea will win it now is if Chelsea suffer a points deduction or if Arsenal win their last five and Chelsea lose their next four. But Man United are still seven points ahead of fifth-place Liverpool, and there is still hope of them finishing second and from there getting the silverware back in 2017 if not next year.