The small southeast Iowa town of New London started construction of a 1.5 MW wind turbine on Oct. 24, 2011. We visited a local farm family and were taken to the site for a close look at what was involved. I wanted to document the size and scope of the equipment needed for such an installation. The ladder into a doorway on the left side of the tower gives a sense of size.
The utility board for the community has historically purchased electric energy from a coop. They felt this installation could help to reduce their long term costs by selling the energy produced by the turbine. It was not expected to produce 100% of the energy needed by the town. But, the energy produced would defray a significant fraction of that which they were now purchasing.
Allow me to promote wind energy production in the state of Iowa. The state ranks at the top in percentage of energy produced by wind with 24.5% in 2012. It is third only to California and Texas in total capacity.
The wind turbine generator is made by the VENSYS company in Germany. Their website offers a video and details about the company. They advertise their gearless generator as more reliable and requiring less maintenance. The blades and tower are made in the United States. Siemens has a blade manufacturing plant in nearby Ft. Madison, IA. I do not know if the blades for this facility came from there.
The gearless VENSYS 1.5 MW requires fewer components, reduces wear and brings higher energy yields. It is the most popular gearless wind turbine in the 1.5 MW class at present – with over 3,000 turbines installed worldwide.
One aspect of the blades that struck me was how curved they are. The attack curve into the wind is clearly visible in this image.
The tower height is 280 feet. The service crane stands the same height in order to be able to lift the generator head and blade assembly for attachment on the top of the tower.
Technical data from the VENSYS pdf. The minimum turbine cut-in speed is with a wind of 3 m/s, nearly 7 mph. The rated speed is 12.5 m/s. Maximum speed cut-out takes place at 22 m/s, nearly 49 mph. The diameter of the blade rotor is 82.34 m. The blades sweep out an area of 5,325 square meters. The operating range is between 9 and 17.3 rpm. Speed control is by microprocessor done remotely from Germany. The rated voltage output is 690 Volts. Power rating is 1.5 Mega-watts.
An interesting and costly aspect of the construction involves the crane. We were told it took 15 semi-trailer flatbeds to haul all of the components of the enormous crane to the site. It could only be assembled on-site. Cost of the crane rental was $1500/hour. This image shows the relative scale of the base of the crane by noting the door to the cab in the center. The entire assembly rested on a layer of 12″ thick wooden planks on top of a gravel bed.
Looking upward, it reached the 280′ height. On top of the crane was an anemometer and vane to monitor wind speed and direction, very important considerations. Lifting the blade assembly for attachment to the generator is a delicate operation.
Sometimes the weather is not very cooperative when construction is taking place. Here is a short video with a similar crane in action during fog at a turbine site in Wisconsin.
The new wind turbine facility will generate enough electricity to power 350 homes. With a Department of Energy study forecasting that electricity prices will increase 50% over the next several years, New London Municipal Utilities decided this would be a good time to install the turbine. Wind energy is clean, unlimited and reduces the need to rely on foreign fuel sources. Using power from the turbine will also annually offset nearly 3,000 tons of carbon emissions that would have been released into the environment by fossil fuel generation facilities.
As we approached the construction site that day, we notice a police car parked across the drive. It appeared someone was sitting in it to monitor the site. On closer approach, it turned out to be a fake. Instead of a policeman, there was a traffic cone on the seat with a cap sitting on top. From the main road a hundred yards away, it appeared to be a person. Very clever.
The town of New London expects a payback on this investment within 20 years. I hope this project turns out to be successful. This small rural Iowa town is like many others. It is very conservative. Given the facts of rising energy costs and the need for electricity, they chose to invest heavily in this technology. Many of the citizens are farmers and good stewards of the land. They know the importance of caring for their resources in order to extend their lifetime. I applaud their forward thinking attitude.
Update to the story…
We revisited the site of the turbine on August 27, 2013, nearly two years after our first visit described above. The tall tower and spinning blades have been visible from miles away as we have traveled on the main highway. Never once have we seen it stopped. On this day, we got to see up close. A follow-up call to the town utility board office allowed me to speak with a representative.
The generator has exceeded expectations. It has produced over 10 million kilowatt-hours of electric energy. That represents about 1/4 to 1/3 of the electrical needs of the town. It has allowed them to sell the excess produced at night-time when the demand is low. It also defrays some of the cost during peak hours when the price rises due to demand. Some excess production has also allowed them to sell to a neighboring community. It appears the project is performing as well as, or better, than expected. It is hoped it will easily meet the goals of their 20 year bond.
Shutdowns have been routine for maintenance. They are currently in the 2nd year of warranty with an option to purchase an additional 3 yrs.