一条公路全长1000千米，一辆汽车8小时行了全程的40%，照这样的速度，行完全程

According to the US government, wind farms off the Pacific coast could produce 900 gig watts of electricity every year. Unfortunately, the water there is far too deep    for even the tallest windmills (see picture) to touch bottom. An experiment under way off the coast of Norway, however, could help put them anywhere.

     The project, called Hywind, is the world's first large-scale deepwater wind turbine (涡轮发电机). Although
it uses a fairly standard 152-ton, 2.3-megawatt turbine, Hywind represents totally new technology. The turbine
will be fixed 213 feet above the water on a floating spar (see picture), a technology Hywind's creator, the
Norwegian company StatoilHydro,has developed recently. The steel spar, which is filled with stones and goes
328 feet below the sea surface, will be tied to the ocean floor by three cable (缆索); these will keep the spar
stable and prevent the turbine from moving up and down in the waves. Hywind's stability (稳定性) in the cold
and rough sea would prove that even the deepest corners of the ocean are suitable for wind power. If all goes
according to plan, the turbine will start producing electricity six miles off the coast of southwestern Norway as
early as September.
     To produce electricity on a large scale, a commercial wind farm will have to use bigger turbines than Hywind
does, but it's difficult enough to balance such a large turbine so high on a floating spar in the middle of the ocean.
To make that turbine heavier, the whole spar's to design a new kind of wind turbine, one whose gearbox (变速
箱) sits at sea level rather than behind the blades (see picture).
     Hywind is a test run, but the benefits for perfecting floating wind-farm technology could be extremely large.
Out at sea, the wind is often stronger and steadier than close to shore, where all existing offshore windmills are
planted. Deep-sea farms are invisible from land, which helps overcome the windmill-as-eyesore objection. If the
technology catches on, it will open up vast areas of the planet's surface to one of the best low-carbon power
sources available.