The following is from an interview with Dennis Noon, senior on-site manager for Navitas Energy, builder of the wind farm
Theres a new wind farm being built in rural Lee County just west of Paw Paw. It consists of 63 towers spread over a total of 2600 acres. Less than one-quarter acre is used for each unit, including pad and crane; the total acreage consumed for the entire farm, including roads, is 130 of the 2,600 acres. This leaves the remaining 2,470 acres for farm land. Each tower is 207 feet from the ground to the center of the rotor . Each blade has a radius of 81.
Tower stability is addressed by means of a 40 feet x 40 feet x 8.5 feet deep reinforced concrete pad, weighing over 1 million pounds and composed of 300 cubic yards of concrete.
Some of the towers are closer together than those in older installations, due to improved technology. Even so, the minimum distance between towers must be at least four blade diameters. Some units are in straight lines along ridges; some are more scattered. Siting is determined by topography to take maximum advantage of wind flow.
Each of the units produces 800 kilowatts (kW). The output of the entire farm is expected to be 54 megawatts (MW), enough to provide electricity to 12,500 average homes.
Electricity is produced by winds ranging from as little as 5 mph through 27 mph. In each machine, an on-board computer, driven by an anemometer, controls the pitch of the blades, a weather station controls orientation, and a computer maintains rotational speeds of 26 to 28 rpm. The nearly constant speed drives the gear mechanism; step-up gears drive the 800 kW generator. At the base of each tower, a transformer steps constantly maintained 690 volts (3 phase)* up to 34,500 volts to be collected at the substation which will soon be built east of the farm. At the substation, voltage is stepped up to 138,000 volts (3 phase)*, which is the acceptable power for ComEd. All electricity produced is alternating current.
The blades are very quiet. Reportedly, the sound they make is no more than the sound of the wind itself blowing past a persons ears.
According to Noon, ice throw is another non-concern. The blades are hand polished and coated with a polymer so that not even dirt will adhere to them. Ice falling on the blades would immediately slide off. In addition to not collecting ice, the highly polished blades are bird friendly. As they turn, they create an air cushion that gently pushes aside any bird near them. The towers also are smooth and polished, affording no place for birds to nest or even roost.
Jobs in concrete working, carpentry, land work, and engineering have been created locally. Navitas policy is to employ local union help in all of their construction projects.
Routine maintenance is expected. Soon after the units are in operation, Navitas crews will change oil, run correlations on production, and assure that there is no unwanted vibration. Every six months, preventive maintenance will be performed.
Ground control will be monitored by fiber optics. Computer communications systems complete with on-board computers will adjust blade pitch and flow of electricity throughout the system. If necessary, the computer system can be manually overridden.
Taxes will benefit the rural area, and be especially helpful to the school system.
Navitas held preliminary public information meetings and will continue to hold them as work progresses on the wind farm and as electricity begins to flow.
* Technically written VAC (3ø)
Next time: Public impressions of the new wind farm.