Business Green: Students at Cambridge University have unveiled plans for a solar-powered racing car designed to cruise at 60mph while using the same amount of energy it takes to power a hair dryer. Codenamed Bethany, the car is on schedule to be completed this summer and will race in the World Solar Challenge, a 3,000km race across the Australian Outback. As well as featuring ultra-lightweight materials and a six-metre-square ‘solar skin’, the car will boast an array of technical innovations, …