Feb. 25

　　There were a couple of strange things about the Virgin Atlantic Boeing 747 that taxied out along one of London Heathrow's two main runways and took off into the bright sky late Sunday morning. First, there were only five people on board, while more than 100 watched intently from a nearby hangar. Second, the plane was the first commercial jet ever to fly on biofuel. "This is the first stage on a journey towards renewable fuel," Virgin founder Richard Branson told reporters in the hangar shortly before takeoff.

　　As it happens, Virgin's eco-plane ran only one engine on the experimental fuel; the other three burned standard jet fuel. And the biofuel-powered engine was using a blend of conventional jet fuel and biofuel: 80/20 in favor of the regular stuff.

　　用生物燃料飞机能飞吗？

　　星期天上午晚些时候，维珍公司一架波音747沿着伦敦希思罗机场的主跑道滑行并起飞冲入明亮的天空。对此有两件奇怪的事。首先，飞机上只有5个人，而有100多人在附近的一个机库中紧张地观看。其次，这架飞机是第一架使用生物燃料飞行的商用喷气式飞机。在机库里，维珍公司的创始人理查德·布兰森在飞机起飞前不久告诉记者：“这是通向使用可再生燃料道路上的第一阶段”。

　　具体的情况是：维珍的这架生态飞机上只有一个引擎使用试验性燃料，其他三个引擎仍使用标准的航空燃料。使用生物燃料的引擎所用的是一种传统航空燃料和生物燃料的混合燃料，比例为80：20，标准燃料占多数。