It should come as little surprise that the surGE inrenewable power and the high-tech revolution have occurred at roughly the same time. Both thrive on innovation and the general trend toward doing more with less.
The late architect and scientist, R. Buckminster Fuller, coined the term “ephemeralization” to describe the tendency of technology to last a short period of time before becoming obsolete and being replaced. If he were alive to witness the current explosion in innovation, the forward-thinking philosopher would be pleased to see the accuracy of his term.
Renewable power and the high-tech explosion, in many respects, have fed off of each other. Renewables provide a new source of electricity to help meet the rising demand that is caused, in part, by the growing reliance on high technology. On the other hand, new innovations in technology have made it possible for renewable power to become productive, efficient and affordable enough for the general population.
Along those lines, renewables have followed vastly different trajectories toward achieving their maximum utility. Historically, for example, the domain of solar power has been almost exclusively small, residential and commercial users. Only recently has it made strides toward becoming a viable wholesale commodity with the fledgling development of concentrated solar.
Wind power, on the other hand, is almost always seen as a wholesale resource, entirely in the domain of utilities. Megawatt wind farms with gigantic turbines are the norm. Now, even that model is showing signs of change as manufacturers and consumers alike discover the sun is not the only renewable source of electricity that can be harnessed as a small source of distributed power.
The American Wind Energy Association (AWEA) defines small wind turbines as those with rated capacities of 100 kilowatts (kW) and less. The organization tracks the market for small wind in its annual global market study. The most recent study found the market for small wind grew 15 percent in 2009 with 20.3 megawatts (MW) of new capacity and $82.4 million in sales. That equates to nearly 10,000 new units, which pushed the total installed capacity in the United States to 100 MW.
Industry expansion is clearly on a steep upward trajectory. According to the AWEA study, half of the 100-MW capacity was installed in the last three years of the industry’s 80-year history. That growth is expected to continue. The study found the world’s leading manufacturers predict continued exponential sales growth in the U.S. market over the next five years, with more than 1 gigawatt of cumulative installed small wind capacity in the United States by 2015.
With all of that expected activity, it makes sense to look at the choices that are available to consumers. There is no shortage of manufacturers offering small wind turbines for residential users. They range in size, capacity, technology and in the unique manner in which they try to harness the wind. In this regard, they have shown great creativity.
What’s out there?
For many, the thought of a small residential wind turbine probably conjures up images of the good old-fashioned tower-mounted windmill on the family farm. While those traditional turbines were used to drive pumps that drew something out of the ground, typically water or oil, modern turbines use the same physics to generate what is considered an equally precious resource: electrical power.
One model that somewhat resembles the traditional turbine, at least in appearance, is the Swift Wind Turbine manufactured by Cascade Renewable Energy, Grand Rapids, Mich. At 250 pounds and with blades that stretch only 7 feet, it is reasonably compact and lightweight. The company promotes the turbine as “rooftop-mountable,” although it can also be mounted on top of a pole. Its advantages are clearly geared toward rooftops. In addition to its light weight and small size, it needs only about 2 feet of clearance between blades and roof.
The company promotes low noise levels as one of the Swift’s biggest selling features. The design of the turbine includes an outer “diffuser ring” that connects the tips of all five blades to eliminate noise caused by vibrations. According to Cascade Renewable, the turbine emits less than 35 decibels at any wind speed.
The Swift has a capacity of 1.5 kW at peak production and will produce 1 kW at 11 meters per second or 24.6 miles per hour. It will produce between 1,200 to 1,900 kilowatt-hours over the course of the year if wind speeds average between 5 meters per second (11.2 mph) and 6 meters per second (13.4 mph) on an annual basis.
Of course, the Swift is not the only innovative product on the market. Nor is its manufacturer the only proud parent. Windspire Energy in Reno, Nev., has taken the design of the traditional turbine and turned it sideways to capture the wind. While traditional turbines rotate on a horizontal axis, the Windspire’s axis is vertical. It uses wind foils, which rotate in tight spirals around a pole, not propeller blades.
In contrast to its propeller cousins, the Windspire captures winds by lift, not drag, at all angles and at low speeds. Its output is roughly the same as, if not slightly higher than, the Swift, at 1.2 kW. Its average annual production is 2,000 kWh at average annual wind speeds of 11 mph.
While the difference in power output may be slight, what sets them apart are the situations in which they can best perform. Unlike the Swift, the Windspire—as a 30-foot tall structure—is not suited for rooftop-mounting on a typical residence. However, residences with ample land can install the pole-mounted turbine. Not, commercial users, including agricultural enterprises, government buildings, schools and corporations have been drawn to the Windspire.
When asked how his company’s product differs from some of its competitors, Brian Levine, Windtronics spokesperson, said it’s very different. Rather than driving a rotor that powers a generator, the Windtronics device, which is licensed as the Honeywell Wind Turbine, uses the patented Blade Tip Power System to create what the company describes as a “gearless, frictionless and virtually silent small wind turbine.”
Essentially, the company has taken the concept of a generator and turned it inside out. The device, which looks like a large fan, contains several blades with magnets on their tips. The blades rotate inside a circular perimeter that contains copper electrical coils. Electricity is generated along the coils as the magnetic blade tips pass by in their wind-driven, circular motion. The turbines also begin rotating at very slow wind speeds, as low as mph, so they don’t use up valuable energy revving up to the speeds needed to generate power. According to Levine, the turbines can start generating electricity at 2 miles per hour and will provide a “reasonable output” at 10 miles per hour.
While many manufacturers of small wind turbines feature one signature product, some offer whole lines. Aliso Viejo, Calif.-based WePower manufactures the Falcon line of vertical axis turbines. They range in height from 10 to 20 feet and are mounted on masts that are from 18 to 30 feet high. The Falcon line features five different turbines, the smallest of which is rated at 600W of capacity. The largest tops out at 12 kW.
The company takes a realistic view of its product, promoting its two smallest turbines for “off-grid, battery charging.” According to company president Howard Makler, the smallest turbine “does not generate a lot of power at lower wind speeds.”
Makler said that the turbines are best suited for ranches and homes with some land. They also suit the commercial sector, where one or two turbines are often installed in one location.
The same realistic approach can be applied to all small wind turbines. In fact, manufacturers consistently say the turbines are unlikely to provide all the energy needed in a location.
Beyond their limited capacity, local zoning laws can also be an issue. While opposition is not necessarily fierce, many local codes simply do not speak to the issue of small wind turbines because they are so new. However, as demand grows, awareness is also growing, and proponents are aggressively lobbying local governments to pass the appropriate standards. Christian Bishop of Windspire in Reno said the company’s local dealers have had to lobby “almost every municipality” where the turbines have been installed.
Property owners also have to consider whether a small wind turbine is ideal for their location. Homes and buildings in areas with low wind speeds or where buildings or trees otherwise obstruct the wind will not be a good fit. Manufacturers provide online tools for prospective buyers to evaluate their wind speeds and determine if the local resource is strong enough to justify a small wind turbine.
Of course, cost is a consideration. A 30 percent federal tax credit combined with state, local and/or utility incentives make the upfront costs more affordable, but in locations where electricity is cheap and/or wind speeds are low, it still may not pencil out.
According to Jessica Lehti, senior sales manager for Cascade Renewable Energy, which manufacturers the Swift, demand is greatest in the Northeast coastal areas and in Western states, such as California and Colorado, which have the ideal combination of high wind speeds and generous incentives.
Lastly, there is the issue of land. Many turbines are small by comparison and are advertised as roof-mountable, but many also are not suitable for the typical single-family dwelling in suburban neighborhoods. Pole-mounted turbines require adequate setback and can only be installed on properties with a certain amount of real estate.
Like so many new developments in the renewable-energy field, optimism prevails. Manufacturers are bullish on growing demand and have formed vast networks with local installers. The Windspire boasts a network of more than 100 dealers nation wide. Fans of the Swift turbine can find one at their local Lowes hardware store. Recently, WindTronics announced an alliance with the National Electrical Contractors Association (NECA) and local NECA chapters to facilitate the installation of the Honeywell Wind Turbine.
So while there may not be a small wind turbine on every roof any time soon, there is still a sizable opportunity for the technology to play an expanding role in the nation’s energy market.
“There are 40 million properties [in the United States] with one half acre or greater,” said Levine, summing up the possibilities. With that kind of math, it is hard not to see a vast untapped market for small wind turbines.
LAEZMAN is a Los Angeles-based freelancer writer who has been covering renewable power for more than 10 years. He may be reached at firstname.lastname@example.org.