By Amy Berry

Traditional Wind Farm Site Disadvantages Are Actually Advantages in Urban Settings

For most who hear the words “wind power” the mind conjures up images of towering white propellers in a wide open rural setting. These large propeller turbines, also known as horizontal axis wind turbines (HAWTs), are the standard in the large wind industry due to their excellent efficiency in converting wind to power. However, what makes them ideal for large scale wind farms (large and remote open spaces with consistent wind direction) does not necessarily make them a great fit for urban sites. In fact, the traditional limitations of vertical axis wind turbine (VAWT) technology for wind farm applications can actually turn into advantages for more urban locations.   Increasingly, homeowners and small businesses are considering VAWTs to help overcome the challenges associated with many small wind sites.

It is important to understand the difference between HAWT and VAWT technology to understand why each is well suited to particular applications. HAWTs have blades which rotate vertically around a horizontal axis, similar to a propeller on an airplane.  Propeller turbines need to be oriented perpendicular to the direction of the wind to be efficient, and in variable or more turbulent wind conditions they need to constantly re-orient themselves, losing efficiency in the process. Propeller blades are designed to use lift to propel themselves around faster than the speed of the wind. The part of the blade near the hub turns at a reasonable speed, because of their rigid outstretched blades, but the tips whir around at greater speeds; this is known as tip speed ratio. Typically the tip speed ratio of a HAWT is seven to ten times the speed of wind.

While HAWTs are efficient in using lift to maximize energy transfer and electricity production, the main drawback in an urban setting is that their tip speeds can create high levels of noise which can be bothersome to neighbors.  Some more modern HAWT designs seek to lessen noise by employing special curvature in the blades. And while wind direction in the open spaces of wind farms is fairly consistent, wind direction in urban settings is often changing.  HAWTs are not able to adapt quickly to changing wind directions, and thus operate extremely inefficiently in more turbulent conditions, as compared with VAWTs.

VAWTs include two main classes: a tall vertical airfoil style (Darrieus), and a solid winged style (Savonius). Darrieus Turbines come in a few varieties.  Some have rotors with curved blades that look like an eggbeater and rotate about a vertical axis. Another variation uses straight-sided airfoils and is called a Giromill.  Like propeller turbines, Darrieus turbines utilize some lift to capture wind energy and operate with tip speed ratios in the lower-middle range. Savonius Turbines have rotors with solid vanes or “scoops” which rotate about a vertical axis (picture an anemometer), using “drag” to allow the wind to push them around. The principle drawback of Savonius turbines is that drag produces far lower energy efficiency than the other types of wind turbines.

Traditionally VAWTs are not recommended for large wind energy production because they are a little less efficient than HAWTs, and do not scale as well to very large applications.  However, the ability of VAWTs to operate silently and efficiently in variable and turbulent wind conditions make them a viable option for urban locations in which these are common site characteristics.  The fact that they operate at lower rpm’s and with tip speed ratios only 2-3 times the wind speed means that they can produce power without creating noise.  VAWTs also readily capture wind energy from any direction, allowing them to work with the constant changing wind directions in urban settings.

At the end of the day, the most important factor is power output.  If a VAWT is able to provide ample energy output in an urban setting, then it is a real option for homeowners, small businesses and governments to consider.

Amy Berry can be found on twitter @wind2power tweeting about small wind power and the Windspire wind turbine.

by Zach Hagadone via idahobusiness.net

Bob Lewandowski may have been among Idaho’s greatest do-it-yourselfers. As a farmer on 20 acres between Boise and Mountain Home he saw his seeds blown from the ground by a seemingly constant wind. Finally, after years of kicking and scratching at the soil, he realized if he couldn’t raise a crop from the earth, then maybe he could harvest something from the sky: electricity.

Betting the farm on wind power, Lewandowski invested a total of more than $120,000 to purchase, ship and refurbish three old turbines from California. Inventing his own performance-boosting repairs, he labored for about three years before hoisting the first 150-foot tower himself.

“He always thought, ‘There’s a lot of power there in the wind – that force ought to be good for something,’” recalled his widow, Illa Vermeulen. “‘We can’t have things growing out here, but I can make electricity.’”

It turned out he was right. Enough wind rifled through that one turbine to power between 15 and 20 homes, and Lewandowski saw the potential for a thriving business. As one turbine became three, a power purchase agreement was struck with Idaho Power Co. and the Gem State’s first commercial wind farm was born.

“I was for him all the way,” said Vermeulen, now 69 and living in Meridian. “When he started it other people thought, ‘Oh, well, this is a pipe dream.’ … He was actually a genius. He would look at something and say, ‘Oh, I can do that better.’”

But Lewandowski’s wind farm was short-lived. In 2005 he passed away from a heart attack and his towers stood idle. Now, with help from a range of public and private partners, Lewandowski’s pioneering wind farm is getting a second life as a teaching aide for energy experts being taught at the College of Southern Idaho and Idaho State University.

“These turbines were really sending the wrong message just standing on the side of the road, not functioning,” said Todd Haynes, an energy systems and research engineer at Boise State University. “[Now] they’re going to be put to good use in Idaho.”

Haynes’ involvement with Lewandowski’s turbines began about three years ago, when he and his father Craig Haynes, an electrician; mechanical engineer Lars Dorr; aircraft mechanic Tim Harmon; and Brian Jackson, of renewable energy consulting firm Renaissance Engineering, formed G3 LLC and purchased the farm.

Though all coming from engineering or mechanical backgrounds, the partners were flabbergasted by Lewandowski’s modified designs. Without schematics, every snag became an ordeal.

“It was like the problem du jour, everyday something would break,” Haynes said. “We would spend dozens of hours out there and it would be a $7 part. … We kept that up for about a year-and-a-half, and then we deemed it doable but not profitable.”

In 2007 the wind farm was mothballed, and went right back to being one of the state’s least appealing wind power advertisements.

Soon after, though, Haynes and his partners were approached by Ridgeline Energy Vice President Rich Rayhill, whose company is developing between 90 and 130 megawatts of wind capacity in eastern Idaho. He told them about the new training programs at CSI and ISU, and that the turbines would make perfect hands-on teaching aides.

With donations of time, labor and expertise from Ridgeline, the Tidwell Idaho Foundation, Idaho Falls-based Eagle Rock Timber, California firms Frontier Pro Services and enXco Service Corporation, and New Jersey-based Hytorc, the turbines were finally taken down, disassembled and shipped to CSI and ISU late last month.

“It’s a typical Idaho story – there’s something that needs to get done and people move together to get it accomplished,” Rayhill said. “The upshot of it is going to be that even if we educate and train more kids than we can fill space with now, the schools in Eugene (Ore.) and The Dalles (Ore.) are turning away three kids for every one they’re letting in, and they’ve got 10 to 12 jobs for every kid they turn out.”

Scott Rasmussen, chair of the Electronics Department at ISU, cited estimates from the American Wind Energy Association that 30,000 new technicians will be needed to meet the Obama administration’s goal of using wind for 20 percent of the nation’s supply by 2030. At the same time, droves of current technicians are facing retirement. “If that begins to happen there’s going to be huge demand, and salaries will follow,” he said.

ISU’s wind tech program is run out of the Energy Systems Technology and Education Center (ESTEC), where Rasmussen serves as executive director. He said about 100 students are currently enrolled, and recent graduates have gone on to find careers in the industry with starting salaries ranging from the high-$40,000s to $70,000.

“We see a vast majority of our graduates leave after two years of school for salaries that are equal to or higher than what our faculty are making,” Rasmussen said. But combined with cutbacks to higher education, that makes it hard to attract expert faculty.

“We certainly are hopeful that the state will recognize programs such as ours and help us maintain the ability to supply graduates who are in high demand locally, regionally and nationally,” he said.

Budget cuts are one problem, but another is the relative weakness of Idaho’s wind industry. According to the American Wind Energy Association, Idaho ranks 13th in the nation for wind power potential, but 23rd for installed capacity, with only 147 MW. That’s compared to Washington and Oregon, which are ranked 5th and 6th for installed capacity – with 1,479 MW and 1,363 MW, respectively – but 24th and 23rd for wind potential.

“That’s kind of frustrating to me because we’ve got the resources, but we’re just not moving expeditiously to develop it,” Rayhill said, though he praised Idaho Power for its recent announcement that it will purchase 150 MW of wind energy over the next three years.

“Between our 90 to 130 megawatts that’s coming on-line in 2010 and Idaho Power’s commitment to 150 megawatts, there’s going to be the kind of development that Idaho should see,” he said. “It’s coming and it’s coming right now by the vision of Idaho’s energy leaders – at least at Idaho Power.”

Another wind farm in the works is Renewable Energy Systems America’s 400 MW China Mountain Wind Energy Project, planned for a site southwest of Twin Falls. The development is in the early stages of an environmental impact statement and officials don’t expect a decision until 2011.

But, while many see wind as a potential cornerstone in the state’s economy, Idaho’s energy czar, Paul Kjellander, takes a more cautious tone.

“In Idaho we have some decent wind sites – three-plus category wind that is in sufficient clusters that I think you can do some large scale development [on],” he said. “[But] at the core of all of it will be transmission. Without transmission we won’t be able to get any of that to market.”

He pointed to seven major transmission projects, either under way or planned to cross the state, as key to whatever energy resources Idaho chooses to develop. Until then, Kjellander said the state is involved in two projects to map and assess wind potential, and is pursuing other resources just as actively.

“You’ve got to be aware – or beware – of those merchants of magic bullets. Renewable technologies are maturing and some of them are very mature, but no single resource is going to get us to where we need to be,” he said. “I don’t care if it’s going to be clean coal technology, natural gas, wind, solar, nuclear, geothermal, biomass or biogas – none of them by themselves will get us to where we need to be. All of them together, collectively, will get us there.”

In the meantime, though, many hope Idaho’s first wind farm will help plant the seeds for an industry driven by partnerships like the one that moved it from a roadside attraction to a green-tech teaching tool.

“Love it or hate, it’s got a lot of history here in Idaho and it’s had plenty of publicity and notoriety,” Haynes said. “We think it’s a nice ending to the story that now these turbines will be used to train the next generation of engineers who will hopefully be working on bigger and better turbines in Idaho.”

Wind farms generally improve the scenery of locations that were not that picturesque to begin with. According to a study in Geographical Research published by Wiley-Blackwell, wind farms have a negative impact on landscapes with a high scenic quality, but a positive effect on dull and mundane landscapes.

In the paper titled “Scenic Perceptions of the Visual Effects of Wind Farms in South Australian Landscapes”, over 300 participants rated the scenic qualities of 68 photographed landscapes with, and without, digitally added wind farms.

Author Dr. Andrew Lothian says, “While people may be apathetic the appearance of wind farms, their location is critical. Wind farms in scenic areas, particularly the coastal areas, are regarded as damaging to the landscape. However, in agricultural areas of low scenic quality, wind farms seem to beautify the otherwise mediocre surroundings.”

The research also finds that the negative visual effects did not reduce with distance or size of the farm and people tend to prefer turbines that are white, blue or grey over tan and rainbow-colours.

Wind farms have been constructed all over the world as a way to increase the generation of renewable energy and reduce dependence on fossil fuels. The main opposition to the construction of wind farms is based on the negative visual impact they have on the landscape.

This study adds to a growing body of international research on community attitudes to wind farms, and contributes useful knowledge for the planning and design of wind farms by taking into account community perceptions.-Wiley-Blackwell