Renewable Energy: “Small Wind” For On-Site Generation

By Anne Cosgrove
Published in the May 2010 issue of Today’s Facility Manager

As more facility managers (fms) consider the use of renewable energy, it is important they evaluate the various source types (e.g., wind, solar, geothermal) for their particular needs. Fms can keep several aspects in mind during the evaluation and decision making process. Questions to consider include: What do we want to gain with renewable energy? Can our site/building accommodate the physical infrastructure? What are the costs/savings, and what financing options are available to us?

When it comes to wind energy, fms may able to source this power from their utility, or they can choose to install a system on their site. The latter option of on-site generation requires research to identify the potential for a system at the location in question. The energy generating rated capacity that most facilities will be looking for—100 kilowatts (kW) and below—is classified by the industry as “small wind.” Installed capacity in this segment of the industry grew by 78% during 2008 (this includes commercial and residential), according to the Washington, DC-based American Wind Energy Association (AWEA). Ron Stimmel, small systems manager at AWEA, notes that while growth for 2009 did not keep the pace of 2008, capacity continued an upward swing.

Fms considering wind energy can begin by considering the following: the wind resource at their site to determine how much energy can be captured; available land on which to locate turbines and related equipment; permitting issues and other site specific concerns.

Wind resource evaluation is a critical element in projecting turbine performance at a given site. A qualified consultant will be able to provide the necessary calculations, but fms can use a wind resource map (like the one shown here that measured annual average wind speeds at 80 meters up) to begin the evaluation process. In general, annual average wind speeds of five to eight meters/second (11 to 17 miles/hr) are required for grid connected systems (the majority of commercial applications).wind energy resource map

How to read the color bars at the bottom left of this map: The olive green bar indicates winds averaging of 4.0 meters/second; the green bar above that indicates winds averaging 4.5 m/s. Moving upward, each color bar indicates an additional .5 m/s, with the blue bar at top indicating 10 or more m/s wind speed averages.

While a wind resource map is a good starting point, they lack the close-up view required for evaluating a small wind project. Those maps provide tracking data of wind higher up than most small wind turbines would be, so for individual facilities, the landscape can be considerably different. As Stimmel notes, “Small wind is applicable to all sorts of facilities, but it is very site specific. Landforms and even vegetation can affect how much energy will be available. A site could even have enough wind on one side of the building, while the other side may not be suitable to capture enough energy.”

Wayne Hildreth, president of Jacksonville, FL-based Wind Energy Consulting & Contracting, Inc., recognizes high level wind resource maps as “good prospecting tools” for small wind projects. “They are a good first step for evaluating a site to determine if you should take the next step,” he says. For fms, the next step can be working with a firm like Hildreth’s, which provides detailed evaluations of a facility’s wind resource and, if the project goes forward, acts as the facility owner’s representative.

Determining a facility’s actual wind resource and the amount of energy an fm can expect to capture typically takes about one year, says Hildreth. “We measure the wind at a site for 12 months—it could be 18 months for larger projects—and then correlate the findings with longer term data. Prior to this, a preliminary analysis using airport data on wind speeds in the region can be conducted. This is an early step in determining if there is sufficient wind at the site.”

Besides determining available wind resource, fms should look at their sites to evaluate if this energy source is a good fit. Generally, one acre of land should be allotted for a small wind turbine. This allows for ample space around the equipment as well as room for a “fall zone”—suitable land in case the structure comes down. Turbines for small wind applications are generally between 80′ to 120′.

Shadow flicker is another issue; this is the amount of time in the course of a year that a window on a building will be affected by the shadow of a turbine.

Looking beyond the site, fms need to check their community’s wind energy ordinances to ensure compliance. Not all communities have such ordinances in place, however, and, in this case, fms can take measures to facilitate acceptance of the project. Hildreth says, “Especially if wind turbines are a new to the community, you want to be responsible and get community buy-in as early as possible. Noise studies can be conducted to make sure neighbors aren’t going to be impacted, for instance. Even though turbines don’t create loud noises, some people object to the swish which can be heard if you’re standing under it.”

If located near an airport, fms will also need to apply with the Federal Aviation Administration (FAA) to make sure a wind system would not affect the take off and landing of aircraft. Additionally, the National Telecommunications and Information Administration (NTIA) needs to be consulted for a microwave analysis to made sure the system would not affect cell phone transmission.

Paying for a small wind system is another issue. In October 2008, small wind systems were added as an eligible technology under an existing Investment Tax Credit (ITC). Then, the stimulus funding in the 2009 American Recovery and Reinvestment Act (ARRA) expanded this to provide a 30% ITC on these systems (until then, there were caps on the benefit). While that is a boon unto itself for those who want to install a system, organizations that have civil work started by December 31, 2010 can now convert the credit into a cash grant totaling 30% of the cost. The ITC is set to expire at the end of 2016, with AWEA working to have the cash grant option extended beyond 2010.

Wind is referred to as a variable energy source, which means that it can be expected to provide a portion of a facility’s power needs. With the right conditions at their locations, fms may find it is a good way to increase their clean energy portfolios.

Research for this article included interviews with Hildreth ( and Stimmel (

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