Embed Size (px)
For more technology stories, visit newscientist.com/technology
15 October 2011 | NewScientist | 23
Smart sensors foil flickering wind turbinesCOMPLAINTS about wind turbines are nothing new – the noise of the machines and their impact on picturesque landscapes are common irritants. But there is another hated side effect: shadow flicker.
“Shadow flicker drives people mad, even if they keep their curtains shut or their blinds down,” says Angela Kelly, head of Country Guardian, a British anti-wind-turbine pressure group.
As each turbine blade sweeps around, repetitive, strobing
shadows can be cast on houses when the sun is low in the sky. Outdoors, it is distracting, but inside it is even worse – some people who experience flicker liken it to having the lights continually switching on and off (see video at bit.ly/qAX6kD).
A possible solution is at hand. Vestas Wind Systems, a turbine maker in Randers, Denmark, has developed a predictive system that works out when shadow flicker is about to happen and stops the turbine rotating until the sun moves the shadows onto uninhabited land.
The measure is designed to head off an oft-cited objection in local authority wind farm planning enquiries, says Bruno Lund Mathiasen, a Vestas engineer.
Called the Vestas Shadow Detection System, the technology is based on software that computes four risk factors: the angle and position of the sun, the distance of the wind turbine to any potentially affected properties, the radius of the rotor blades and the height of the turbine hub from the ground.
Light levels are assessed using two light meters placed on the east and west-facing sides of a wind turbine’s support tower. If one is reading very high light levels while the other is low, it means the weather is set for very strong shadow production shortly after sunrise or before sunset, says Vestas spokesman Michael Holm.
Once the risk of shadow flicker has been calculated, the software decides whether the turbine should be temporarily shut down.
“The turbine will be put in idle mode, which means we twist the blades so the rotor turns very slowly. This stops any shadow flickering,” says Mathiasen. “Based on its calculation of the shadow effect, the system will decide by itself whether to put the turbine in idle mode or not.”
The system has been shown to be effective in tests at 50 Vestas sites around the world, Holm claims.
Mathiasen will not say how much Vestas will charge the firms that operate turbines for the technology, but Kelly thinks any price would be too much. “If Vestas is serious about this they ought to contact anyone with wind turbines causing flicker problems and offer them this technology for free,” she says. Paul Marks n
“Shadow flicker drives people mad, even if they keep their curtains shut or their blinds down”
RIP Steve JobsOne of the most influential technologists of the personal computing era, Apple founder Steve Jobs, died last week. Tributes to Jobs’s genius flowed in from a vast range of sources, from the White House to former rivals like Microsoft founder Bill Gates. Famous for being a perfectionist, Jobs was never afraid to visit harsh criticism even on his own employees. But the products he oversaw – the iMac, iPhone and iPad were only the latest – changed the world of consumer technology. “He made the information revolution not only accessible but intuitive and fun,” US president Barack Obama said.
Planes fly greenerThree fuel-efficient planes competed for speed and efficiency in the NASA Green Flight Challenge earlier this month in Santa Rosa, California. Sponsored by Google, the contest called for small aircraft carrying two passengers to be able to fly using an average 100 miles per gallon (85 kilometres per litre). Teams used both electric and fossil-fuel engine designs built into sleek carbon-fibre bodies to reduce weight and aerodynamic drag. The winner of the efficiency category, team Pipistrel-USA.com, took home $1.3 million in prize money – one of the largest sums ever awarded for an aviation contest.
Play tennis with the greatsWhat’s better than an overhand smash or deft drop shot in Wii Sports Tennis? Doing it against Raphael Nadal or the Williams sisters. Jui-Hsin Lai and colleagues at the National Taiwan University in Taipei have come up with a way to play that puts you in control of actual athletes – or at least a video of them. Tennis Real Play analyses video of a real match and turns it into a playable game. The game extracts clips of the players and the ball, and smoothly blends them to create a controllable character. Each athlete’s avatar is unique, based on his or her real-world playing style.
ONE PER CENT
For breaking tech news go to: newscientist.com/onepercent