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| HISTORY Pioneer in the North Sea
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Dimitri R. Stein | ||
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This is the story of the first post World War II German wind power plant designed with modern aeronautical and control technology that, for a period of 20 years, operated in the estuary of the Elbe River. Except for Denmark and the Soviet Union, wind-powered electric generation on a major scale was not introduced in Western Europe until the 1970s. Therefore, the Insel Neuwerk plant can be considered to be a forerunner of the large-scale use of wind as an electrical power source. LocationNeuwerk is a tiny island along the estuary of the Elbe River northwest of Cuxhaven and is about 10 km (6.2 mi) from the mainland (see Figure 1). The island is 3.5 km2 (1.35 mi2) in area with only about 40 permanent residents. Today, Neuwerk is part of the Hamburg Mud Flats (or shallows) National Park and is a vacation destination for tourists and regular visitors alike. The area between the island and the mainland is under water at high tide and changes to mud flats at low tide (see Figure 2). At low tide, the island can be reached on foot (about two hours) or by horse-drawn wagon (about one hour). At high tide, visitors arrive by vessel and disembark at the boat basin or at the nearby ship landing.While Neuwerk has been a popular vacation spot for many years, the principal structures on the island immediately after World War II were several farmhouses and a tall and imposing brick defensive tower completed in 1310 to guard the mouth of the Elbe River. Located on the south side of the island, this tower served for centuries as a daytime reference point for navigation to and from Hamburg, Germany’s largest port. In the 1640s, a navigation light was first established on Neuwerk. This open-fire beacon at the top of a simple wooden lattice structure was fueled by anthracite coal shipped from Scotland. In 1814, the defensive tower was converted into a lighthouse, and the present copper-covered beacon structure and pyramidal roof were installed at that time. Figure 3, Figure 4, and Figure 5 show the lighthouse as it appears today. Despite the recent construction of a tall radar tower just offshore on the west side of the island, the lighthouse remains a prominent structure on the island’s skyline. Today, there are several small hotels on the island, one of which is located on the lower floors of the lighthouse. It should be noted that Hamburg is planning a celebration in 2010 to commemorate the 700th anniversary of the Neuwerk fortification and lighthouse. For some years prior to the end of World War II, the electricity needed to power the lighthouse beacon and to supply several small farm and residential uses had been supplied by two diesel electric generators feeding a direct current (dc) system operating in parallel with a battery. With the severe shortage of diesel fuel after World War II, a different power source was urgently needed. Because of the distance to the mainland and the difficult installation conditions, a submarine power cable could not be laid to connect with the local utility on the mainland. With average wind velocities of 5.5–6.5 m/s (18–21.3 ft/s), wind conditions in the area were favorable for the use of wind power. Given these prevailing winds, a decision was made in 1946 to erect a wind power plant to supplement the diesel generators. This decision was made by Überlandwerk Nord-Hannover AG, the local utility that was responsible for power supply to the island and primarily to the lighthouse. This decision led to the construction of the first modern wind power plant in Germany. The manufacturer of the unit was the Nordwind Company, organized by the author and located in Porta Westfalica, about 200 km (124 mi) southwest of Insel Neuwerk. Dipl.-Ing. Franz Villinger led the Nordwind design team and supervised the erection of the wind turbine unit. Wind Turbine Design and LayoutThe wind turbine that was designed and built was named the Universal-Windmotor Nordwind, Type 100/15 (see Figure 6). The unit was a horizontal-axis aero turbine with three blades having a rotor diameter of 15 m (49.2 ft) and mounted on a 20 m (65.6 ft) high guyed steel tower. An auxiliary rotor behind the main blades placed the aero turbine in the optimum wind position and also moved the rotor blades out of the wind beginning with a wind velocity of 9 m/s (29.5 ft/s) until it placed the rotor in a neutral position at a velocity of 14 m/s (45.9 ft/s). The control of the wind turbine rotational velocity was accomplished by an adjustment of the movable lower end of the blades through the use of a spring-loaded aerodynamic braking mechanism (see Figure 7). The highest wind velocity of 40 m/s (131.2 ft/s) corresponding to 144 km/h (89.5 mi/h) was measured on 1 December 1950, with no damage to the plant.The power transmission was effected over a vertical shaft driving a bevel gear and using a belt to drive a 110/160-V dc generator located at the foot of the tower. The plant’s nominal power output was 11 kW at 6.5 m/s (21.3 ft/s) or 18 kW at 8.0 m/s (26.2 ft/s) wind velocity. The design of the rotor is of interest. The blades were built to have an optimum efficiency at 5 m/s (16.4 ft/s), which roughly corresponds to the prevailing average wind velocity. The rotation factor (tip speed velocity divided by wind speed) is 7.5. Modern contemporary wind power plants operate with much slimmer blades and have higher rotation factors. Table 1 lists the operating data of the power plant for 1950. For that year, approximately 68% of the energy used was supplied by wind power, with the balance being provided by the diesel units. Except for the July to September tourist season, the wind power plant generated about 80% of the island’s energy requirements. There was no output from the wind power plant in December 1950 because a bearing had to be replaced on the wind turbine. By about 1970, the development of polymer insulated and water resistant power cables made it feasible to lay a cable from the mainland to Neuwerk. Still, for a period of 20 years, the wind power plant at Neuwerk operated successfully and generated substantial savings. EpilogueThe Insel Neuwerk wind turbine unit was retired and dismantled some years ago. Today, its important role in the life of the island is but a memory for those old enough to remember the unit’s construction and operation. But, for a score of years, the lighthouse beacon that the wind turbine helped illuminate both guided ships to safe anchorage and heralded the advent of large-scale wind power development on Germany’s North Sea coast.For Further ReadingW. Mackenthun, “Wind power plant Neuwerk,” (in German), Elektrizitaetswirtschaft, vol. 50, pp. 322–325, Nov. 1951.D. R. Stein, “Statistical analysis of the energy production of wind power plants,” (in German), Elektrizitaetswirtschaft, vol. 50, pp. 279–285, Oct. 1951, and pp. 325–329, Nov. 1951. D. R. Stein, “Utilization of wind power in the USSR,” (in German), Elektrizitaetswirtschaft, vol. 40, pp. 54–56, 1941. D. R. Stein, “Importance and advances in the utilization of wind power in Denmark,” (in German), Elektrizitaetswirtschaft, vol. 41, pp. 346–349, 370–374, and 390–392, 1942. M. Griepentrog. (2009) Neuwerk information and photo galleries [Online]. Available: http://www.insel-neuwerk.de | |
