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January 06, 2009 - 08:03:44 PM
Via the website of New York Sun Works - Sustainable Engineering
What is the Science Barge?
The Science Barge is a prototype, sustainable urban farm and environmental education center. It is the only fully functioning demonstration of renewable energy supporting sustainable food production in New York City. The Science Barge grows tomatoes, cucumbers, and lettuce with zero net carbon emissions, zero chemical pesticides, and zero runoff. It is powered by solar, wind, and biofuels, and irrigated by rainwater and purified river water. READ MORE »
January 02, 2009 - 10:03:38 PM
And the evolution of the car means the evolution of the entire transportation model. When we eliminate the dependence on oil, we eliminate the environmental and economic damage that came with it.
The good news is we’re evolving into something very familiar. The Better Place business model is one most of us already experience every day - with our mobile phones. READ MORE »
January 02, 2009 - 08:32:56 PM
Harnessing the current: An artist's rendition of how a commercial VIVACE system might look. Passive bars, positioned horizontally, are boxed together in a single unit that could be placed at the bottom of a river or in the path of an ocean current. Dozens of 500-kilowatt units could be grouped together in different configurations to create multimegawatt systems.
The world's river and ocean currents carry an enormous amount of kinetic energy, but most of this water flows slower than four miles per hour. Existing turbine and water-mill technologies can't generate enough electricity at such speeds to make their deployment economically viable.
Researchers at the University of Michigan say that they have overcome this limitation by taking advantage of energy-packed vortices that are formed when water flows past a cylindrical object, even at low speeds. Salmon and trout are known to leverage the force created by these naturally occurring water swirls so that they can swim upstream. A new mechanical device designed to economically harvest that energy and convert it into electricity could turn waterpower into a much larger part of the world's renewable-energy mix.
"Anywhere we have currents, we can use it," says Michael Bernitsas, a professor in the department of marine engineering at the University of Michigan. He says that the first test of the device will be in the Detroit River, likely in 2010. "If we make it work, and I believe it will, it's going to be a major development," he says. READ MORE »
December 26, 2008 - 11:25:46 PM
Pelamis Wave Power Ltd. (PWP) is the manufacturer of The Pelamis Wave Energy Converter, a unique system that generates renewable electricity from ocean waves.
The fully operational wave farm consists of three P1-A Pelamis machines with a generating capacity of 2.25 MW (3 x 750kW) which according to Alternative Energy News will produce enough energy to power 1500 homes at peak hours. READ MORE »
December 26, 2008 - 11:15:14 PM
Credit: FloDesign Wind Turbine
FloDesign Wind Turbine, has developed a wind turbine that could generate electricity at half the cost of conventional turbines.
The company recently raised $6 million in its first round of venture financing and has announced partnerships with wind-farm developers.
The company's design, which draws on technology developed for jet engines, circumvents a fundamental limit to conventional wind turbines.
Typically, as wind approaches a turbine, almost half of the air is forced around the blades rather than through them, and the energy in that deflected wind is lost. At best, traditional wind turbines capture only 59.3 percent of the energy in wind, a value called the Betz limit.
FloDesign surrounds its wind-turbine blades with a shroud that directs air through the blades and speeds it up, which increases power production. The new design generates as much power as a conventional wind turbine with blades twice as big in diameter. The smaller blade size and other factors allow the new turbines to be packed closer together than conventional turbines, increasing the amount of power that can be generated per acre of land. READ MORE »
November 26, 2008 - 08:47:52 AM
Factories, data centers, power plants--even your clothes dryer--throw off waste heat that could be a useful source of energy. But most existing heat-harvesting technologies are efficient only at temperatures above 150 °C, and much waste heat just isn't that hot. Now Ener-G-Rotors, based in Schenectady, NY, is developing technology that can use heat between 65 and 150 °C.
The company replaces the turbine in a typical electrical generator with a device called a gerotor, which it claims to have made "near frictionless." "If this works, it's so huge," says Bob Bechtold, president of Harbec Plastics, one of Ener-G-Rotors' potential customers. "I've been dreaming about the concept of using [low-temperature waste heat] ever since I first knew what it was about . . . It's all about using what we have more completely."
Ener-G-Rotors' technology is based on the Rankine cycle, in which heated fluid flowing through a tube heats a pressurized fluid in a second tube via a heat exchanger. The second tube is a closed loop; the so-called working fluid flowing through it (a refrigerant with a low boiling point, in the case of Ener-G-Rotors) vaporizes and travels into a larger space called an expander. There, as the name would imply, it expands, exerting a mechanical force that can be converted into electricity.
Instead of turning a turbine, the expanding vapor in Ener-G-Rotors' system turns the gerotor, which is really two concentric rotors. The inner rotor attaches to an axle, and the outer rotor is a kind of collar around it. The rotors have mismatched gear teeth, and when vapor passing between them forces them apart, the gears mesh, turning the rotor.
The company claims that the rotor design is far simpler than that of a turbine, making it potentially easier and cheaper to manufacture, as well as more durable. And the company says that it has invented a proprietary way of mounting the rotor on rolling bearings that makes its movement nearly frictionless.
Reducing the friction means that the rotor turns more easily, so the gas doesn't need to exert as much force to generate electricity. That's why the system can work at lower temperatures, which impart less energy to the gas. READ MORE »
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