Philips Lighting, the world’s biggest manufacturer of LED lights, has offered a boost to the energy efficiency industry with a new pledge to sell two billion LED lightbulbs by 2020. The promise, delivered today to energy ministers gathered in San Francisco for the Clean Energy Ministerial summit, will include all Philips LED bulbs sold between 2015 and 2020. The move is expected to save the amount of energy equivalent to 60 coal-fired power stations -…