The Next Generation of Wind

06/01/2015 | By Jennie Morton

Vertical axis turbines provide a compact alternative

Vertical axis wind turbines

Considering wind energy but don’t have the space for a large turbine? Utility-scale models aren’t the only option that can turn gusts and breezes into renewable power. Unlike its taller cousins, a vertical axis wind turbine (VAWT) has a compact footprint and can be installed on rooftops or a corner of your property. This design flexibility makes it a suitable alternative for urban locations where a traditional turbine is out of the question. Learn how a VAWT can help your facility generate clean power when space is limited.

Spinning with Benefits
Though first designed in the late 1920s, vertical axis turbines aren’t as widespread as other renewable technologies. While modern engineering has ironed out some design challenges, commercial adoption has been eclipsed by systems with more established track records, namely horizontal axis wind and solar.

Vertical axis turbines come in two basic forms – those with S-shaped scoops or ones with blades that resemble an egg beater. Either version is omnidirectional, meaning they can accept breezes from any direction, says Paul Schneider, vice president of marketing for CGE Energy, a provider of wind solutions. This is a significant advantage over horizontal turbines, which must be facing into the wind to spin.

“Efficiency-wise, the capacity of these turbines approaches that of utility-scale models,” says Ryan Gilchrist, assistant director of business development for Urban Green Energy (UGE), a turbine manufacturer. “While not as high, the output is still high enough to gain strong economic returns.”

Though payback is variable depending on generation, utility rates, and quality of siting, owners can expect a 5- to 15-year payback, Schneider notes.

The petite stature, lower center of gravity, and lighter design of VAWTs also enable installation possibilities that simply can’t be achieved with a mega turbine.

Those on the shorter end of the spectrum are typically placed on rooftops. Less than 30 feet high on average, their height is unlikely to interfere with aviation traffic. Furthermore, their slim profile means that the weight can be supported by commercial roofs. They can be installed directly above an existing building column, though additional reinforcement may be required, explains Gilchrist.

If the roof isn’t an option, freestanding models can be located on an unused patch of your property. These turbines can be comparable in size to a standard area light pole or between 100-150 feet. This is still substantially smaller than utility-scale turbines, which are typically over 300 feet tall when measuring ground to blade tip.

Whether rotating overhead or gracing the edge of your parking lot, these vertical axis turbines are sure to stand out. Considering that solar panels may be obscured by parapet walls and geothermal is hidden underground, vertical axis turbines are an eye-catching way to position your company as an environmental leader.

“Companies looking to make a visual statement about their sustainability initiatives can attract positive attention with these turbines,” Gilchrist says.

As an additional benefit, VAWTs are quieter because their RPMs are lower than utility models, he adds. This means less vibration is carried through the building as well.

These turbines can also contribute to bird safety. Because the blades don’t spin as fast and their arms are shorter than a large turbine, they are easier for birds to see and avoid.

Lastly, access is far easier with VAWTs. Critical components such as the gearbox are often at ground level so no scaffolding or safety harnesses are needed to perform routine maintenance and inspections, says Schneider. Maintenance is similar to larger models with lubrication changes and blade cleaning. Some manufacturers also offer service contracts.

Ensure your warranty, which is typically two to five years, covers routine failures as these turbines are designed to move continuously, Schneider adds.

Hilton Fort Lauderdale Beach Resort

Hilton Worldwide wanted to attract green-minded customers to its resorts for personal lodging and events. Taking advantage of Fort Lauderdale’s strong coastal winds and the building’s 26-story height, the hotel installed six building-integrated turbines on its roof.

The 4 kW turbines stand approximately 52 feet tall and are strategically positioned on each corner and the center of the hotel’s rooftop to capture maximum wind velocity. The VAWTs are projected to produce 24,000 kWh, which supplements 5-10% of the resort’s energy needs.

At an investment cost of over $500,000, annual savings will be between $25,000-$50,000 with a payback of 10-20 years. The turbines are also expected to offset 70,000 pounds of carbon annually. Plans are underway to combine the installation with solar.

“The turbines will help us visualize the hotel as a place to be conscious of energy use. They will help to highlight the importance of conserving electricity and start dialogue,” says Randy Gaines, vice president of engineering for Hilton Worldwide.

INFORMATION COURTESY OF UGE AND HILTON FORT LAUDERDALE BEACH RESORT; IMAGE PROVIDED BY UGE


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