US navy launches first biofuel-powered aircraft carriers

Carrier strike group of four ships is the first to begin operating regularly with a blend of petroleum and biofuels made from beef fat

The US navy on Wednesday launched its first carrier strike group powered partly by biofuel a mix made from beef fat, calling it a milestone toward easing the military's reliance on foreign oil.

The maritime branch touted the warships as the centrepiece of its "Great Green Fleet" part of a navy-wide initiative that aims to draw 50% of its power from alternative energy in four years.