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At January's Detroit Auto Show, Mercedes-Benz eagerly showed off its hydrogen-powered F-Cell car, vowing to prove the viability of fuel-cell vehicles by driving three of them around the world. And now, 18,641 total miles later, it's completed that circumnavigation, arriving safely home at the company's Stuttgart headquarters. Does this prove fuel-cells are ready for prime time? Well, the trip took 70 driving days to cover four continents, and the vehicles' range topped out at just over 400 miles -- in Kazahkstan. But M-B admits there are only 200 refilling stations worldwide; in most cases the F-Cells had to rely on a tag-along mobile refueling unit. The company hopes its demonstration will spur development in a refilling-station infrastructure: having a fuel-cell car you can't easily refuel must feel like owning a flying DeLorean in 1885. Autoblog

Each week our friends at  Inhabitat  recap the week's most interesting green developments and clean tech news for us -- it's the Week in Green.  Green transportation took off for the stars this week as Inhabitat reported that the European Space Agency has approved of a new hydrogen-powered  "Skylon" space plane , and we spotted a hot  Star Wars-inspired electric chopper  that wouldn't look out of place on the Death Star. We also learned that NASA plans to rejoin the space race with a new  MPCV craft  fit for deep space flights, while here on Earth we saw GE harness the power of the sun to  charge Volt EVs  before they hit dealerships. Speaking of solar power, Japan unveiled plans to construct  10 new solar power plants  in the wake of the Fukushima Nuclear Crisis, while  Switzerland announced  that it will completely phase out the use of nuclear power. We also showcased a stunning chandelier made from  500 fl...

Going green is  de rigeur , so the sun is becoming a much-preferred source of power. However, solar cells' inefficient harvesting of heliacal energies is a major reason they haven't usurped the power of petroleum. Good thing the big brains at Oak Ridge National Laboratory are looking to change that with nanocone-based solar technology. The teeny-tiny cones are made of zinc oxide and create "an intrinsic electric field distribution" to improve electrical charge transport within solar cells. We aren't sure what that means, but we do know the prickly-looking design provides a 3.2 percent light-to-power conversion efficiency that's a substantial improvement over the meager 1.8 percent offered by today's flat photovoltaics made of similar materials. That's 80 percent more efficient, and 100 percent more awesome . Physorg ORNL