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Large Wind Turbines

July 21, 2013
Paul Gipe

Hometown Wind Farm A Wildcat


I’ve been working with wind energy for more than three decades. In the early days I dreamed that there might be some adventurous souls in my home town of Alexandria, Indiana who might take a stab at putting up a wind turbine or two.

A few years ago a local resident won the lottery and shortly thereafter he installed a Skystream 3.7 literally down the road from my mom’s place north of town. That was a pleasant surprise. It’s a small turbine, only 3.7 meters in diameter, and it was the only one for some time. Now it has a companion just south of town and that was a pleasant surprise too.

Wind energy is growing in Indiana. Now there are some wind turbines in Upland on the Taylor University campus and there are two commercial-scale turbines Union City as well. Wind farms have also begun to sprout out of Indiana’s corn fields.

I’d been meaning to take some time off when home visiting family to drive up to Lafayette where several large wind farms had been installed in the past few years, but I never got around to it. Once home, like most people I fall into a familiar routine of visiting one relative after another.

Well, now I don’t need to drive to Lafayette after all. They’ve brought the wind farms to me, or more correctly to Tipton and Madison counties.

While home recently for a family reunion I could see a big 200 MW project from just down the road to my mom’s house. The 125-turbine project, Wildcat 1 Wind Farm, is probably no more than five miles from my mom’s and certainly less than 10 miles.

Built by E.ON, the Wild Cat I Wind Farm was completed at the end of 2012 with GE’s 1.6 MW-100 meter diameter turbine. They are a new breed of large diameter turbines for low and medium wind sites that have been a long time in coming.

E.ON is the German company big in the US, Great Britain, and—well—Germany, and the corporate descendent of PreussenElektra.

Electricity from the project is sold to American Electric Power whose subsidiary, Indiana & Michigan Power Co. serves the area.

The turbines are widely spaced across farmland of corn and soy beans. The project is visible from many roads west and north of Alexandria, as well as some roads south of town.

The project is just outside Elwood, Indiana and stretches east toward Alexandria north of State Highway 28. The turbines are apparent from State Highway 9 north from Alexandria at least to Grant County.

Previously, the tallest objects in the area were cell phone towers—and corn.

Project Specs

News reports quote an E.ON executive saying the project cost $400 million. There’s no way to verify that number. If correct, that’s $2,000 per MW of installed capacity or—a better measure of relative cost--about $400 per square meter of rotor swept area.

Annual Generation

E.ON won’t provide estimates of what the project is expected to produce, asserting that the information is confidential.

The wind resource in north-central Indiana is modest. It’s probably in the range of 7.5 m/s at a 100-meter hub height. It could be less, but it’s unlikely to be more. See the Indiana 100-meter Wind Resource Map.

Conservatively, modern wind turbines should generated about 1,200 kWh per square meter of rotor area at sites with a 7.5 m/s annual average wind speed.

Depending upon the actual resource and the performance of the turbines, the project will generate about 1 TWh per year. In 2004, Indiana consumed nearly 130 TWh per year. Wildcat Wind Farm Phase I alone will provide somewhat less than 1% of Indiana’s electricity supply.

Revenues

The company wouldn’t say how much it is being paid for its electricity, again asserting confidentiality.

We can make some reasonable estimates that should at least put us in the ball park.

After the Federal tax subsides, E.ON could sell the electricity for as low as $0.05/kWh or up to $0.07/kWh. It could be more, but it’s not likely to be less. Thus, E.ON could earn from $40 million per year from the project to as much as $80 million per year. Again, we don’t know for sure.


 

Spacing

The Midwest is unlike the windy mountain passes of California and require a much more open spacing. In California wind farms the winds are nearly unidirectional and the spacing reflects this: the turbines are packed close together. In the Midwest, where the winds are more omnidirectional, the turbines need to be spaced much farther apart than those in California.

Despite a news report quoting an E.ON executive that the project occupies 8,500 acres, the company’s PR office says the project actually occupies 17,600 acres or about 28 square miles. In my experience, the PR officers often know more about the details than the executives, because it is their job to do so.

This then translates into a spacing of ~73 square meters of land area per square meter of intercept area for an equivalent spacing of 7 RD by 8 RD.

The metric of land area per swept area is a more reliable metric of spacing than the oft used acres per MW or hectares per MW because the latter are a function of the wind turbine’s specific capacity. As I and others have argued for years, using a wind turbine’s generator capacity as a measure of size is extremely misleading. See Generator Ratings & Capacity Factors: Why You Should Avoid Them. This project particularly illustrates why this is important.

Specific Capacity & Specific Area

I’ve railed for decades about wind turbine manufacturers that used high power ratings relative to their turbine’s rotor area as a means for overselling if not deceiving consumers.

Until recently, manufacturers were primarily focused on designing wind turbines for IEC Class I and Class II resources. These are very wind sites. I and others have argued that we need wind turbines for areas of moderate wind resources like the Midwest of the USA and the central highlands (the Mittelgebirge) of Germany or the plains of central France because this is where the people live. Wind turbines for these areas use large diameter rotors relative to their generator capacity.

We’ve always had some wind turbines like this. Take Vestas’ V82, rated at 1.65 MW, in comparison to its V80, rated at 2 MW. However, now manufacturers are emphasizing such wind turbines with large rotors. Consider that in the mid-2000s the V82 was rated at 1.65 MW and now the GE turbine used in the Wildcat project is rated at 1.6 but employs a rotor 100 meters in diameter.

Interestingly, GE’s 1.6 MW turbine used in this project has a specific capacity of 0.2 kW per square meter of rotor swept area. In my work with small wind, I emphasize a “standard power rating” for all small turbines as a means of comparison and I use 0.2 kW/m2.

In the past, some wind turbines had specific capacities of 0.5 kW/mto 0.6 kW/m2. Windmaster’s turbines were notorious for this. Fayette’s turbines were even worse with specific capacities of 1.2 kW/m2. Fortunately, both companies are long gone.

If it’s not apparent, it’s the rotor area that is the determining factor in how much electricity a wind turbine generates relative to the wind available. This, until recently, was lost on most of those who work professionally in wind energy, including many who should know better.

My colleague Bernard Chabot suggests, and I agree, that a better metric is specific area in m2/kW. The reason is simple. This metric increases as the swept area increases relative to generator size. If we live in the Midwest or central France and want more energy, and hence electricity, we look for a wind turbine with higher number than another. The GE turbines in the Wildcat project have a specific area nearly 5 m2/kW of rated capacity—almost twice that of a Vestas V80 of the mid-2000s and considerably more than the 3.2 m2/kW of the V82 during the same period.

Landowner Royalties

How much E.ON will pay landowners isn’t clear from its public statements. It’s not even clear the term of the contracts, whether they are 30 years as quoted in a local paper or the more typical 20 years.

We can make some reasonable estimates based on past experience.

Royalties are based on gross revenues, not on profit.

Again, we don’t know what E.ON is actually being paid for its electricity nor do we know what they expect the annual production to be. Consequently, we don’t know what the project will earn in gross revenues per turbine. Based on the project earning from $50 to $80 million per year, each turbine will earn from $400,000 to $640,000 per year in gross revenues.

We don’t know either what royalty rate E.ON pays. Royalties in North America are typically low by international standards. I’ve seen some contracts with royalties as low as 1.5% of gross revenues. This could be the exception. We don’t know for sure. Unlike in other countries, land leases in the US are typically confidential. This is to the project owners advantage.

We do know that in Germany, royalties can be as much as 5% of gross revenues. And in many cases, the turbines are either directly owned by the landowner or the landowner is a share-owner of a locally-owned project.

For more on royalties, see Wind Turbine Land Leases, Landowner Guides, Wind Energy Royalties.

Landowners may receive as little as $8,000 per turbine per year or as much as $30,000 per year.

If the same turbines were located in E.ON’s home country, the same turbines would earn about $1,000,000 per year. E.ON would pay a German farmer about $50,000 per turbine per year. Or the German farmer might talk to his neighbors and just decide to do it themselves. The farmer would still receive the lease fee if the turbine was located on their property, but they also would share in any profit from the project. They would also share in the risk. However, German farmers, like those in Indiana, are accustomed to risk. They’re farmers after all.

Overall Impression

E.ON and its contractors have done a good job on the project. The roads to the turbines are modest, reflecting the need to take as little land out of production as possible. Contractors were resurfacing the rural roads in the project with crushed aggregate area when we visited. The turbine pads are clean and tidy. There was no trash, litter, or construction debris. The stenciling on the towers to identify each turbine was large, easy to read, and professionally done. There were no giant logos promoting either E.ON or GE on the sides of the nacelles. The only detraction was the use of external pad-mounted transformers. Many wind projects today place the transformer inside the towers. Over, in its visual appearance on the flat Tipton Till Plain of Central Indiana, Wildcat I Wind Farm is a model project.


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