Posted: 05 Apr 2010 12:30 PM PDT
A 1,550-mile-long network of offshore wind stations could provide power from Massachusetts to North Carolina with minimal threat of outages, according to a new study.
By connecting stations together, the system could eliminate the biggest downside of wind power: intermittency.
The concept is simple: If you spread out wind stations far enough, each one will experience a different weather pattern. So it's very unlikely that a slackening of the wind would affect all stations at once. The result is steadier power.
"We're designing transmission in a different way, according to meteorological principles," said marine-policy expert Willett Kempton of the University of Delaware in Newark, co-author of the research, published April 5 in the Proceedings of the National Academies of Sciences.
Kempton and a team of scientists analyzed five years of wind data from 11 meteorological stations — buoys and towers — off the Atlantic coast, from Florida to Maine. They found that combining power from all stations with a transmission cable could prevent massive power fluctuations.
The scientists simulated an underwater transmission cable, which they called the Atlantic Transmission Grid, that stretched more than 1,550 miles and connected all 11 stations. Although individual sites showed erratic patterns, the aggregate power output changed only very slowly.
For example, the power output of individual stations would regularly drop to zero and fluctuate by more than 50 percent in an hour, but the output of the entire grid did not change more than 10 percent in any given hour. And the north-south orientation of the grid meant that a northward cyclone, which can cause wind power to drop quickly after it passes through, would affect only a few stations at a time. Grid power never dropped to zero during the entire five-year period.
"We took an intermittent resource and made it not intermittent anymore," Kempton said.
Scientists had considered offshore wind as a potentially limitless source of power. Compared to land, the ocean has stronger and more constant winds, though still not constant enough to be a primary energy supply. This study indicates that offshore wind deserves more serious consideration as an energy alternative.
"The technology's there, the materials are there, we have the willpower to reduce carbon emissions, we have a reliable power supply that doesn't lead to fuel shortage," said Mark Jacobson, a civil and environmental engineer at Stanford University. "The next step is really to start implementing this on a large scale."
There are currently no commercial offshore wind stations, though companies have started developing six wind farms along the east coast. Together, the developments could produce as much energy as a large coal or nuclear power plant.
Next, Kempton would like to optimize the selection of stations to get the most stable and robust wind power. The current electric grid cannot handle another large source of variability, so it will be important to design the transmission to ensure that wind power is more reliable, he says.
And he recommends the development of a new regulatory body to oversee offshore wind power. But first developers and investors have to be willing to pony up the large capital costs for building wind farms along the coast.
Images: 1) Data from the QuikScat satellite shows wind-power density over global oceans for winter (top panel) and summer (lower panel). Red and white colors indicate high energy is available, while blue color reflects lower energy./NASA/JPL.
Posted: 05 Apr 2010 12:00 PM PDT
Newly discovered pieces of amber have given scientists a peek into the Africa of 95 million years ago, when flowering plants blossomed across Earth and the animal world scrambled to adapt.
Suspended in the stream of time were ancestors of modern spiders, wasps and ferns, but the prize is a wingless ant (above) that challenges current notions about the origins of that globe-spanning insect family.
"Most specimens represent a unique fossil record of their group from Africa, and some are among the oldest records in the world," wrote researchers in a paper April 5 in the Proceedings of the National Academy of Sciences.
The amber, which is formed when plant resin fossilizes, preserving flora and fauna trapped within, was found in what is now northwest Ethiopia. Ninety-five million years ago, it was part of a disintegrating Gondwana, one of two vast land masses that spawned the seven modern continents.
Most amber deposits have been found in former parts of Laurasia, the other supercontinent of the time. The Gondwana record is relatively sparse.
The amber in the latest study dates to the middle of the Cretaceous era, which followed the dinosaur-dominated Jurassic and witnessed the rise of mammals, birds and flowering plants. Mammals get most of the attention, but changes to flora were just as profound.
Before the Cretaceous, flowering plants —which are now the most diverse type of terrestrial plant — didn't exist. By the mid-Cretaceous, they dominated the land. Existing plants and animals had to adapt, filling the flowery new niches. The new study is a snapshot of that process.
While it will take years to interpret the ecological tales trapped in the new amber, one important story is already suggested. Inside the Ethiopian amber is an ant that looks nothing like ants found in Cretaceous amber from France and Burma. Those deposits had placed the origin of ants in Laurasia. That's no longer certain.
"The Ethiopian amber is of great importance for improving our knowledge of the evolutionary history of terrestrial arthropods, plants and Fungi," wrote the researchers.
Images: Photos From Alexander Schmidt/PNAS: 1) Wingless ant; 2) False fairy wasp; 3) Tree fern; 4) Springtail. Diagram: Breakup of Pangea./USGS.
Citation: "Cretaceous African life captured in amber," by Alexander Schmidt, Vincent Perrichot, Matthias Svojtka, Ken Anderson, Kebede Belete, Robert Bussert, Heinrich Dörfelt, Saskia Jancke, BarbaraMohr, Eva Mohrmann, Paul C. Nascimbene, André Nel, Patricia Nel, Eugenio Ragazzi, Guido Roghi, Erin E. Saupe, Kerstin Schmidt, Harald Schneider, Paul A. Selden, and Norbert Vávra. Proceedings of the National Academy of Sciences, Vol. 107 No. 14, April 5, 2010.
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