Advances in Wind Energy Tech
The world’s largest wind turbine is now a 10MW, floating, 162 meters tall turbine. Its diameter is 145 meters.
Miltary stealth technology may help solve the radar interference issues of wind turbines.
Lancaster Wind Systems proved a feasible way to store wind energy by turning wind energy into hydraulic power, or pressure: inert nitrogen gas can be compressed in thousands of kilometres of unused pipelines creating a sort of giant pressure tank.
New laser wind sensors that helped the BMW Oracle team win the 2010 America Cup will enhance the turbine productivity.
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Rubber trailing edge flaps could result in quieter, more productive wind farms (Gizmag)
If you’ve ever seen a commercial-scale wind turbine in real life, then you’ll know that they’re huge – a single blade can be as long as 60 meters (197 feet). Researchers from Denmark’s Risoe DTU National Laboratory for Sustainable Energy tell us that such blades can flex by up to six meters (20 feet) when subjected to strong wind gusts. Worse yet, that load is often not evenly distributed along the length of the blade, so it doesn’t flex evenly. Fortunately, the researchers are working on addressing this problem, by attaching flexible flaps to the trailing edges of the blades. These flaps come in the form of silicone rubber strips, which run the length of the entire blade. The result, we’re told, will be quieter, higher-output turbines.
The project has been in development since 2006. Last December, a two-meter (six-foot) blade section with one of the rubber edge flaps was tested in a wind tunnel. The results showed that the flap did indeed reduce the deforming forces on the blade, and that the rubber holds its shape even when exposed to heavy winds. A blade that isn’t flexing back and forth, needless to say, will generate power more efficiently. The researchers have also noted that the flaps could make the blade-construction process easier. Blades are currently assembled from two pieces, and the trailing edge must be ground down after they’re put together, to lessen wind noise. Using the flaps, a ready-made, even sharper edge could simply be applied in the form of one long rubber strip.
There is the still the matter, however, of the uneven distribution of wind shear across the surface of the blade. The wind tunnel tests showed that different curvatures of the flaps could compensate for different intensities and directions of wind, but how do you continuously adjust those curvatures? The Risoe team put two sensors on the front of their blade section, which measured wind speed and direction. The data from those sensors was fed into a pneumatic system inside the blade, which changed the shape of the flap by pumping air in or out of it. Presumably on an entire blade, there would be sensors all the way down the forward edge, and the trailing edge strip would be divided into cells that could each assume different curvatures as dictated.
Risoe DTU is now looking towards production and testing of a full-scale prototype.
The random-looking bumps on the humpback whale’s flippers have just inspired a breakthrough in aerodynamic design that seems likely to dramatically increase the efficiency and performance of wind turbines, fans, flippers and even wings and airfoils. WhalePower’s tubercle technology seems like nothing less than a revolution in fluid dynamics.
Current theory would state that the leading edge of a fin, fan or turbine blade should be absolutely straight and smooth for best effect – a ‘fact’ that has been taken for granted for decades. But the more Fish studied the odd leading-edge bumps, or Tubercles, the more it became apparent that evolution’s work on the fin was far ahead of man’s best efforts. Airfoils fitted with tubercle bumps showed much higher lift efficiency and greater stall resistance than identical airfoils without them. Turbines fitted with tubercles to the leading edges of each blade are able to produce more power at low fluid speeds, are quieter, and perform much better in turbulent fluid streams.
It seems the bumps have the effect of channeling air into smaller areas of the blade, resulting in a higher wind speed through the channels and a number of rotating airflows on top of the blade which increase lift. Furthermore, the bumps eliminate the tendency of air to run down the length of the blade’s edge and fly off at the tip, causing noise, instability and a loss of efficiency. In fact „bumps” is probably the wrong word as these are not small protrusions – on a utility scale (50 meter) blade for example, each tubercle would be about the size of a VW Beetle.
After discovering the Tubercle effect, Fish worked with Phil Watts to invent and patent a new type of leading edge for airfoils and hydrofoils. WhalePower was then formed in collaboration with Stephen Dewar with a view to applying these designs to all types of turbines, pumps, compressors or fans.
Wind power generation turbines stand to gain greatly from the discovery; because they can be used at a greater pitch angle with much less drag and much less tendency to stall, they allow turbines to continue generating power at wind speeds that are much too slow for traditionally shaped turbines to operate safely in. Importantly for the turbine market, tubercles can be retrofitted to the leading edge of conventional blades. Real world performance is proving very impressive, leading several major wind farm manufacturers to seek retrofit kits for their existing designs.
The technology is in the early stages of commercialization by WhalePower, which is initially focusing mainly on the wind turbine market as a means of establishing itself. Currently Tubercle Technology is being licensed to manufacturers like Canada’s Envira-North who will bring out the first big fans (24 feet in diameter) in April this year. Definitive R&D testing at the Wind Energy Institute of Canada (WEICan) is also about to take place and negotiations are in progress with a number of manufacturers who make everything from hovercraft fans to the tiny fans that keep laptops cool.
While the company doesn’t expect it to be easy to break into the market, WhalePower co-founder Stephen Dewar is confident that the commercial benefits of the technology will be so easily apparent that we’ll soon see bumpy leading edges on a range of household and commercial goods.
„If we’ve got what we think we’ve got, then the range of applications is staggering,” said Dewar in an interview with The Star, „I’m honestly scared of making claims at this point. The results are so good that we know everybody who knows anything about aerodynamics will think we’re salting the goldmine.”
We look forward to discovering how this nature-inspired technology stands up as a commercial product, and seeing its applications diversify as it matures.
Smarter wind technology looks to improve turbine workrate
Clean, renewable energy is freely available – in the form of wind, sun and water. However, harnessing it reliably and cost-effectively remains a barrier. Wind power is one of the fastest growing alternative energy markets and researchers at Purdue University and Sandia National Laboratories in West Lafayette, Indiana, are working to make wind turbines more efficient, reliable and resilient.
They are using sensors and computational software that constantly monitor forces exerted on wind turbine blades with the aim of developing a smarter wind turbine structure.
Improving reliability and resilience
„Our aim is to do two things: improve reliability and prevent failure. The most direct way to enable those two capabilities is by monitoring forces exerted on the blades by winds,” says Douglas Adams, a professor of mechanical engineering and director of Purdue’s Center for Systems Integrity.
According to doctoral student Jonathan White, who is working on the project with Adams, “the ultimate goal is to feed information from sensors into an active control system that precisely adjusts components to optimize efficiency.”
One of the main problems with wind turbines is that the wind can suddenly change direction and force, decreasing efficiency and causing costly damage to blades. The team from Purdue and Sandia believes its technique can help prevent this by providing real-time information to the turbine’s control system and predicting fatigue.
Sensors were embedded in the turbine blade as it was being built. Testing on a research wind turbine in Texas has shown that using a trio of sensors and „estimator model” software accurately reveal how much force is being exerted on the blades.
In the future, turbine blades could be fitted with flaps like those on an airplane’s wings. Sensors inside the blades would enable blade pitch to be adjusted in real time to respond to changing conditions.
„Wind energy is playing an increasing role in providing electrical power,” says Adams. „The United States is now the largest harvester of wind energy in the world. The question is, what can be done to wind turbines to make them more efficient, more cost-effective and more reliable?”
Alternative energy is big business
The Renewable Energy: Global Industry Guide put the value of the renewables market at USD$246 million in 2007, and there’s no shortage of companies trying to improve on existing technologies and share the profits. Catch the Wind is a Virginia-based company that has developed a fibre optic laser sensor, the Vindicator. It sits atop turbines and measures wind data in real time, allowing adjustments to be made to the turbine well before the wind comes. The company’s research suggests it can provide an increase of up to a 10 percent in turbine output power.
The Leviathan Wind Energizer claims to increase power output by between 15 percent and 30 percent, when the turbine is spinning. It uses aerodynamic modeling to direct the surrounding wind flow to the critical area of the blades, via a passive structure located near each of the turbines.
ExRo Technologies believes its generator reduces costs and increases output by up to 50 percent because more than 90 percent of its energy can be converted into electricity. Rather than use a traditional mechanical generator to compensate for variations in the wind, they have developed a self-adapting electrical system that can scale up and down with available energy in a way that would take almost 70 traditional generators to match.
This isn’t the only example that demonstrates biomimicry can provide answers. We recently covered the Tubercle Technology, a breakthrough in aerodynamic design offering more power, less noise and the ability to generate power at wind speeds that are much too slow for traditionally shaped turbines.