Using ‘Small Wind’ to Power Your Factory

What small child has not been mesmerized by small windmills—the kind with twisted strips of plastic attached to a nail on the end of a stick? Just a puff sets it spinning and brings smiles of pure joy.

Is it this childhood fancy that explains the plethora of manufacturing entrepreneurs and inventors gravitating to the growing small wind industry? Or is it because there is real gold in the venture? Or, perhaps it is based on the belief that at some time in the near future, electricity is going to be so expensive that the best way to generate it will be on-site?

With more than 450 models of small wind electricity generators available or under development, small wind is either on the edge of an exploding market or one of the largest cauldrons of misguided judgment in technological history. Globally, wind power is one of the fastest-growing sources of renewable electricity.

Rooftop systems fall into the “Small Wind” category, defined as wind turbines that generate up to 100 kilowatts (kW). These systems are categorized by where they are mounted, their orientation—horizontal facing upwind (with a tail), horizontal facing downwind, or vertical—and whether they tie directly to the electricity grid or charge a battery.

Small Wind turbines are either building-mounted or pole-mounted.

Building-mounted Wind Systems—No Tower Required. These turbines are the smallest because they need to be quiet and efficient (see Figure 1). Also called rooftop wind systems, they work well in urban areas and are quite suitable for manufacturing plants.

No need to install a tower—these systems are building-mountable. Most building-mounted turbines can be attached to the side of a building or directly onto the structure of a flat roof via a flat roof stand.

Most building- or structure-mounted turbines connect directly to the grid. This enables you to use your wind-generated electricity first, and to access additional power from the local utility. Most times, you will be required to have grid-connected technologies installed by manufacturer-trained installers.

Figure 2The Northwind 100, manufactured by Northern Power Systems, is rated at 100 kW. It has a gearless design using permanent magnet direct-drive technology. The turbine begins making power at wind speeds as low as 3 meters per second (6.7 mph). Photo courtesy of Northern Power Systems, Barre, Vt.

Pole-mounted. The most common class of small wind turbines on the market is pole-mounted (see Figure 2 and Figure 3). They range in size and capacity from small systems that provide a trickle charge to a battery or other applications to the largest, which use a power converter that interconnects power to local power grids. Pole-mounted turbines are also suitable for use in manufacturing plants, as well as rural areas.

Pole-mounted wind turbines vary in size from less than 1 kW (1,000 watts of instantaneous power) to well over 1 MW (1 million watts of instantaneous power). The very large wind turbines are primarily used in industrial wind farms. Most commercial or residential applications for pole-mounted wind turbines use equipment in the 1 to 250 kW range.

Turbines for manufacturing facilities, other businesses, and schools usually are mounted on poles no taller than 150 ft. A typical residential wind turbine is mounted on a pole that is 50 to 120 ft. tall.

When considering any type of wind turbine installation, it is important to contact your local utility and city or township board to find out what interconnection and building permits are required. Permitting and interconnection procedures vary widely. Typically, a trained installer will assist customers with the entire process

All of these variations undoubtedly propagate the large number of available models. But the distinctions do not stop there. How do you know what you are buying?

Rating System: Two Measures

Ratings standards are just now emerging that measure the watts generated in a way that is more comparable, but they are not yet perfect.

One standard is the installed capacity that measures the output when the generator is operating at 11 meters per second (24.6 mph).

The annual energy production (AEP) is the output if the turbine is operating at 5 meters per second for the entire year.

Actual Versus Estimated Performance

Figure 4In 11 MPH annual average winds, a Windspire® turbine generates approximately 2,000 kWh a year. The pole-mounted turbine stands 30 ft. tall and 4 ft. wide. Photo courtesy of Windspire, Reno, Nevada.

Obviously the performance you actually realize depends on the strength and volume of the wind at your particular site. In general, the higher the turbine is located, the more wind speeds increase and are more consistent. In terms of cost-efficiency, the counterpoint is that the higher up the device is mounted, the higher the installation costs as well.

So the magic of locating a wind turbine is all about positioning it at the highest height possible at the lowest mounting cost (see Figure 4).

To assess how much wind your site will actually produce, a clever device is available at www.chooserenewables.com that estimates actual wind energy production, based on your location, shown on National Renewable Energy Laboratory (NREL) maps (see Figure 5) or Google maps.

And if you want take the next step, an anemometer can be rented for a three or four months to collect wind data specific to your site. You can then purchase an analysis of your data compared to nearby airport data to provide a more exact estimate of actual wind production at your site.

Does Small Wind Make Sense for My Plant?

Tax Incentives. Currently, a federal incentive is available in the form of a 30 percent tax credit on the total installed cost of purchasing wind turbines and other renewable-energy devices. It scheduled to sunset in 2016.

In addition, many states offer significant incentives as well. The state and federal tax credits combined can amount to 60 percent off of the total installed cost of the wind turbine.

Investment Payoff. There are many reasons why you might want to invest in an on-site wind system. One is that once you pay for it, the wind system keeps returning energy cost benefits for years to come.

Building-mounted wind systems are installed in 1-kW units. They can cost approximately $10,000 to $12,000 per 1 kW of installed capacity.

Pole-mounted wind systems can be installed in sizes up to 100-kW units. These can cost from $450,000 to $550,000 per 100 kW of capacity, depending on the site preparation and controls system.

Also, investing in wind demonstrates a commitment to renewable energy and to the reduction of greenhouse gases. The SWIFT Wind Turbine, for instance, generally goes to carbon neutral after four years of operation.

You may want to install a system for the educational value, to demonstrate the energy being produced. Another reason to invest in wind energy is that it truly adds real estate value and interest to your property.

While calling them “kinetic sculptures” may be a bit over the top, there is a sense of grace, energy, and wonder about wind turbines.