108-507: The Richard I. Bong Memorial Bridge , also known as the Bong Bridge , connects Duluth, Minnesota , and Superior, Wisconsin , via U.S. Highway 2 (US 2). Opened on October 25, 1984, it is roughly 11,800 feet (3,600 m) long, including about 8,300 feet (2,500 m) over water. It crosses the Saint Louis Bay , which drains into Lake Superior . The bridge rises 120 feet above
216-402: A blade length up to 80 meters (260 ft). Designs with 10 to 12 MW were in preparation in 2018, and a "15 MW+" prototype with three 118-metre (387 ft) blades is planned to be constructed in 2022. The average hub height of horizontal axis wind turbines is 90 meters. Vertical-axis wind turbines (or VAWTs) have the main rotor shaft arranged vertically. One advantage of this arrangement
324-444: A blow to the city's economy whose effects included the closure of the cement company, which had depended on the steel plant for raw materials (slag). More closures followed in other industries, including shipbuilding and heavy machinery . By decade's end, unemployment rates hit 15 percent. The economic downturn was particularly hard on Duluth's West Side, where ethnic Eastern and Southern European workers had lived for decades. During
432-542: A city. By 1857, copper resources were scarce and the area's economic focus shifted to timber harvesting. A nationwide financial crisis, the Panic of 1857 , caused most of the city's early pioneers to leave. A history of Duluth written in 1910 relates, "Of the handful remaining in 1859 four men were unemployed and one of those was a brewer. Capital idea; build a brewery. The absence of malt and hops and barley did not at all embarrass those stout-hearted settlers." The water for brewing
540-441: A gearbox, which turns the slow rotation of the blades into a quicker rotation that is more suitable to drive an electrical generator. Some turbines use a different type of generator suited to slower rotational speed input. These don't need a gearbox and are called direct-drive, meaning they couple the rotor directly to the generator with no gearbox in between. While permanent magnet direct-drive generators can be more costly due to
648-412: A greater friction moment and thus a lower power coefficient. The air velocity is the major contributor to the turbine efficiency. This is the reason for the importance of choosing the right location. The wind velocity will be high near the shore because of the temperature difference between the land and the ocean. Another option is to place turbines on mountain ridges. The higher the wind turbine will be,
756-474: A lower blade speed ratio, which lowers blade bending stresses. Straight, V, or curved blades may be used. These are drag-type devices with two (or more) scoops that are used in anemometers, Flettner vents (commonly seen on bus and van roofs), and in some high-reliability low-efficiency power turbines. They are always self-starting if there are at least three scoops. Twisted Savonius is a modified savonius, with long helical scoops to provide smooth torque. This
864-457: A network of streetcars and an inclined railroad , the 7th Avenue West Incline Railway , that, like San Francisco's cable cars, climbed a steep hill. The change in elevation is illustrated by Duluth's two airports. The weather station at the lakeside Sky Harbor Airport on Minnesota Point has an elevation of 607 feet (185 m), while Duluth International Airport, atop the hill, is 820 feet (250 m) higher at 1,427 feet (435 m). Even as
972-572: A series of batteries . The batteries powered various electrical tools and lamps, as well as a threshing machine. Friedländer's windmill and its accessories were prominently installed at the north entrance to the main exhibition hall (" Rotunde ") in the Vienna Prater . In July 1887, Scottish academic James Blyth installed a battery-charging machine to light his holiday home in Marykirk , Scotland. Some months later, American inventor Charles F. Brush
1080-663: A shed of 60 feet (18 m), a large warehouse, and a canoe yard. Over time, Indian peoples and European Americans settled nearby, and a town gradually developed. In 1808, German-born John Jacob Astor organized the American Fur Company . The company began trading at the Head of the Lakes in 1809. In 1817, it erected a new headquarters at present-day Fond du Lac on the St. Louis River. There, portages connected Lake Superior with Lake Vermilion to
1188-417: A stable environment. Different materials have varying effects on the efficiency of wind turbines. In an Ege University experiment, three wind turbines, each with three blades with a diameter of one meter, were constructed with blades made of different materials: A glass and glass/carbon epoxy , glass/carbon, and glass/polyester. When tested, the results showed that the materials with higher overall masses had
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#17328587349461296-692: Is 90.2 inches (2,290 mm). The lake steams in the winter when moist, lake-warmed air at the surface rises and cools, losing some of its moisture-carrying capacity. Wind turbine A wind turbine is a device that converts the kinetic energy of wind into electrical energy . As of 2020 , hundreds of thousands of large turbines , in installations known as wind farms , were generating over 650 gigawatts of power, with 60 GW added each year. Wind turbines are an increasingly important source of intermittent renewable energy , and are used in many countries to lower energy costs and reduce reliance on fossil fuels . One study claimed that, as of 2009, wind had
1404-419: Is a major drawback. Vertical turbine designs have much lower efficiency than standard horizontal designs. The key disadvantages include the relatively low rotational speed with the consequential higher torque and hence higher cost of the drive train, the inherently lower power coefficient , the 360-degree rotation of the aerofoil within the wind flow during each cycle and hence the highly dynamic loading on
1512-431: Is approximately 50% of the building height it is near the optimum for maximum wind energy and minimum wind turbulence. While wind speeds within the built environment are generally much lower than at exposed rural sites, noise may be a concern and an existing structure may not adequately resist the additional stress. Subtypes of the vertical axis design include: "Eggbeater" turbines, or Darrieus turbines, were named after
1620-623: Is determined by the stiffness of fibers and their volume content. Typically, E-glass fibers are used as main reinforcement in the composites. Typically, the glass/epoxy composites for wind turbine blades contain up to 75% glass by weight. This increases the stiffness, tensile and compression strength. A promising composite material is glass fiber with modified compositions like S-glass, R-glass etc. Other glass fibers developed by Owens Corning are ECRGLAS, Advantex and WindStrand. Carbon fiber has more tensile strength, higher stiffness and lower density than glass fiber. An ideal candidate for these properties
1728-718: Is land and 8.510 square miles (22.04 km ) is water. It is Minnesota's second-largest city by land area, surpassed only by Hibbing . Duluth's canal connects Lake Superior to the Duluth–Superior harbor and the Saint Louis River . It is spanned by the Aerial Lift Bridge, which connects Canal Park with Minnesota Point (or "Park Point"). Minnesota Point is about 7 miles (11 km) long, and when included with adjacent Wisconsin Point , which extends 3 miles (4.8 km) from
1836-404: Is now Piedmont Heights, and, of course, a widespread area of Northeastern Minnesota." In the fire's aftermath, tens of thousands of people were left injured or homeless; many of the refugees fled into the city for aid and shelter. For the first half of the 20th century, Duluth was an industrial port boom town dominated by its several grain elevators , a cement plant, a nail mill, wire mills, and
1944-574: Is often used as a rooftop wind turbine and has even been adapted for ships . Airborne wind turbines consist of wings or a small aircraft tethered to the ground. They are useful for reaching faster winds above which traditional turbines can operate. There are prototypes in operation in east Africa. These are offshore wind turbines that are supported by a floating platform. By having them float, they are able to be installed in deeper water allowing more of them. This also allows them to be further out of sight from land and therefore less public concern about
2052-586: Is on the north shore of Lake Superior at the westernmost point of the Great Lakes . It is the largest metropolitan area, the second-largest city, and the largest U.S. city on the lake. Duluth is accessible to the Atlantic Ocean, 2,300 miles (3,700 km) away, via the Great Lakes Waterway and St. Lawrence Seaway . The Port of Duluth is the world's farthest inland port accessible to oceangoing ships and
2160-449: Is regarded as a classic. The nearby city of Proctor, Minnesota , is named for Knott. Duluth's unofficial sister city, Duluth, Georgia , got its name in 1871, shortly after Knott's speech gained national attention. Prominent Georgia newspaperman and politician Evan P. Howell was called upon to make remarks at the dedication of a new railroad line into Howell's Crossing, a village named for his grandfather. Howell humorously suggested that
2268-520: Is that the turbine does not need to be pointed into the wind to be effective, which is an advantage on a site where the wind direction is highly variable. It is also an advantage when the turbine is integrated into a building because it is inherently less steerable. Also, the generator and gearbox can be placed near the ground, using a direct drive from the rotor assembly to the ground-based gearbox, improving accessibility for maintenance. However, these designs produce much less energy averaged over time, which
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#17328587349462376-537: Is the largest and busiest port on the Great Lakes. It is also among the top 20 U.S. ports by tonnage. Common items shipped from Duluth include coal, iron ore, grain, limestone, cement, salt, wood pulp, steel coil, and wind turbine parts. Duluth is a popular Midwest tourist destination. The city is home to the Great Lakes Aquarium , a freshwater aquarium. The Aerial Lift Bridge , next to Canal Park , crosses
2484-448: Is the spar cap, a structural element of a blade that experiences high tensile loading. A 100-metre (330 ft) glass fiber blade could weigh up to 50 tonnes (110,000 lb), while using carbon fiber in the spar saves 20% to 30% weight, about 15 tonnes (33,000 lb). Instead of making wind turbine blade reinforcements from pure glass or pure carbon, hybrid designs trade weight for cost. For example, for an 8-metre (26 ft) blade,
2592-513: The Duluth Ship Canal into the Duluth–Superior harbor. Minnesota Point , known locally as Park Point, is the world's longest freshwater baymouth bar , stretching 6 miles (10 km). The city is also the starting point for road trips along the North Shore of Lake Superior to Thunder Bay , Ontario . The Ojibwe occupied a historic settlement at Onigamiinsing ("at the little portage"),
2700-682: The Duluth Works plant. Handling and export of iron ore, brought in from the Mesabi Range, was integral to the city's economy, as well as to the steel industry in the Midwest, including in manufacturing cities in Ohio. The Aerial Lift Bridge (earlier known as the "Aerial Bridge" or "Aerial Ferry Bridge") was built in 1905 and at that time was known as the United States' first transporter bridge —only one other
2808-534: The Duluth Works steel plant, US Steel developed Morgan Park , as a company town for steel workers. It is now a city neighborhood within Duluth. The Diamond Calk Horseshoe Company was founded in 1908 and later became a major manufacturer and exporter of wrenches and automotive tools. Duluth's huge wholesale Marshall Wells Hardware Company expanded in 1901 by opening branches in Portland, Oregon , and Winnipeg , Manitoba ;
2916-570: The Earth's crust thinned, magma rose toward the surface. These intrusions formed a 16 km (9.9 mi)-thick sill , primarily of gabbro , which is known as the Duluth Complex . The creation of the Lake Superior basin reflects the erosive power of continental glaciers that advanced and retreated over Minnesota several times in the past 2 million years. The mile-thick ice sheets easily eroded
3024-545: The Finnish Socialist Federation and then the IWW operated Work People's College , an educational institution that taught classes from a working-class, socialist perspective. Immigrants from Sweden , Norway , Denmark , Germany , Austria , Czechoslovakia , Ireland , England , Italy , Poland , Hungary , Bulgaria , Croatia , Serbia , Ukraine , Romania , and Russia also settled in Duluth. At one time, Duluth
3132-533: The Fourth of July , 3,500 people were present to celebrate. In the first Duluth Minnesotian printed on August 24, 1869, the editor placed the following notice on the editorial page: Newcomers should comprehend that Duluth is at present a small place, and hotel and boarding room accommodation is extremely limited. However, lumber is cheap and shanties can be built. Everyone should bring blankets and come prepared to rough it at first. In 1873, Cooke's empire crumbled and
3240-531: The Iron Range north of Duluth; ore shipments from the Duluth harbor had been critical to the city's economy. Low-grade ore ( taconite ) shipments continued, boosted by new taconite pellet technology, but ore shipments were lower overall. In the 1970s the United States experienced a steel crisis , a recession in the global steel market, and like many American cities Duluth entered a period of industrial restructuring. In 1981, US Steel closed its Duluth Works plant,
3348-577: The North West Company established several posts on Minnesota rivers and lakes, and in areas to the west and northwest, for trading with the Ojibwe, the Dakota , and other native tribes. The first post was where Superior, Wisconsin , later developed. Known as Fort St. Louis, the post became the headquarters for North West's new Fond du Lac Department. It had stockade walls, two houses of 40 feet (12 m) each,
Richard I. Bong Memorial Bridge - Misplaced Pages Continue
3456-514: The Second World War , as Duluth's large harbor and the area's vast natural resources were put to work for the war effort. Tankers and submarine chasers (usually called "sub-chasers") were built at the Riverside shipyard. The population of Duluth continued to grow in the postwar decade and a half, peaking at 107,884 in 1960. Economic decline began in the 1950s, when high-grade iron ore ran out on
3564-556: The U.S. Highway 53 corridor from Trinity Road to Maple Grove Road. The highway project reconstructed connector roads, intersections, and adjacent roadways. A new international airport terminal was completed in 2013 as part of the federal government's Stimulus Reconstruction Program. The geology of Duluth demonstrates the Midcontinent Rift , formed as the North American continent began to split apart about 1.1 billion years ago. As
3672-532: The portage across Minnesota Point between Lake Superior and western St. Louis Bay, which forms Duluth's harbor. For both the Ojibwe and the Dakota, interaction with Europeans during the contact period revolved around the fur trade and related activities. According to Ojibwe oral history , Spirit Island, near the Spirit Valley neighborhood, was the "Sixth Stopping Place", where the northern and southern branches of
3780-499: The sandstone that filled the axis of the rift valley but encountered more resistance from the igneous rocks forming the flanks of the rift, now the margins of the lake basin. As the last glacier retreated, meltwaters filled the lake to as high as 500 feet (150 m) above the current level; the Skyline Parkway roughly follows one of the highest levels of the ancient Lake Superior, Glacial Lake Duluth . The sandstone that buried
3888-467: The stock market crashed , and Duluth almost disappeared from the map. But by the late 1870s, with the continued boom in lumber and mining and with the railroads completed, Duluth bloomed again. By the turn of the century, it had almost 100,000 inhabitants, and was again a thriving community with small-business loans, commerce and trade flowing through the city. Mining continued in the Mesabi Range and iron
3996-428: The "lowest relative greenhouse gas emissions, the least water consumption demands and the most favorable social impacts" compared to photovoltaic , hydro , geothermal , coal and gas energy sources. Smaller wind turbines are used for applications such as battery charging and remote devices such as traffic warning signs. Larger turbines can contribute to a domestic power supply while selling unused power back to
4104-497: The 11th and 12th centuries; there are reports of German crusaders taking their windmill-making skills to Syria around 1190. By the 14th century, Dutch windmills were in use to drain areas of the Rhine delta. Advanced wind turbines were described by Croatian inventor Fausto Veranzio in his book Machinae Novae (1595). He described vertical axis wind turbines with curved or V-shaped blades. The first electricity-generating wind turbine
4212-541: The 1980s, plans were underway to extend Interstate 35 through Duluth and up the North Shore , bringing new access to the city. The original plan called for the interstate to run along the shore on an elevated concrete structure, blocking the city's access to Lake Superior. Kent Worley, a local landscape architect, wrote an impassioned letter to then mayor Ben Boo asking that the route be reconsidered. The Minnesota Department of Transportation agreed to take another look, with Worley consulting. The new plan called for parts of
4320-602: The 7th century. These " Panemone " were vertical axle windmills, which had long vertical drive shafts with rectangular blades. Made of six to twelve sails covered in reed matting or cloth material, these windmills were used to grind grain or draw up water, and were used in the gristmilling and sugarcane industries. Wind power first appeared in Europe during the Middle Ages . The first historical records of their use in England date to
4428-655: The American government. As part of the Treaty of Washington (1854) with the Lake Superior Band of Chippewa , the United States set aside the Fond du Lac Indian Reservation upstream from Duluth near Cloquet, Minnesota . As European Americans continued to settle and encroach on Ojibwe lands, the U.S. government made a series of treaties, executed between 1837 and 1889, that expropriated vast areas of tribal lands for their use and relegated
Richard I. Bong Memorial Bridge - Misplaced Pages Continue
4536-540: The Atlantic and Pacific oceans. Soon the lumber industry, railroads and mining were all growing so quickly that the influx of workers could hardly keep up with demand, and storefronts popped up almost overnight. By 1868, business in Duluth was booming. In a Fourth of July speech Dr. Thomas Preston Foster, the founder of Duluth's first newspaper, coined the expression "The Zenith City of the Unsalted Seas". In 1869–70, Duluth
4644-512: The Betz limit of power extractable from the wind, at rated operating speed. Efficiency can decrease slightly over time, one of the main reasons being dust and insect carcasses on the blades, which alter the aerodynamic profile and essentially reduce the lift to drag ratio of the airfoil . Analysis of 3128 wind turbines older than 10 years in Denmark showed that half of the turbines had no decrease, while
4752-578: The Duluth Waterfront Collective. One notable example includes the Highway 61 Revisited concept, which seeks to reimagine the I-35 corridor as it runs through the city's downtown. The group's efforts have been met with interest, with the city council voting to explore options for the corridor in 2021. While the acreage of land utilizing the waterway for port-related purposes has shifted in recent years,
4860-492: The Duluth area, Fond du Lac (Bottom of the Lake) in 1654 and again in 1660. The French soon established fur posts near Duluth and in the far north where Grand Portage became a major trading center. The French explorer Daniel Greysolon, Sieur du Lhut , whose name is sometimes anglicized as "DuLuth", explored the St. Louis River in 1679. After 1792 and the independence of the United States,
4968-459: The Duluth area. The fire was the worst natural disaster in Minnesota history in terms of the number of lives lost in a single day. Many people died on the rural roads surrounding the Duluth area, and historical accounts tell of victims dying while trying to outrun the fire. The News Tribune reported, "It is estimated that 100 families were rendered homeless by Saturday's fire in the territory known as
5076-466: The French inventor, Georges Darrieus. They have good efficiency, but produce large torque ripple and cyclical stress on the tower, which contributes to poor reliability. They also generally require some external power source, or an additional Savonius rotor to start turning, because the starting torque is very low. The torque ripple is reduced by using three or more blades, which results in greater solidity of
5184-587: The Great Lakes to processing plants in Illinois and Ohio. Ten newspapers, six banks and an 11-story skyscraper, the Torrey Building, were founded and built. As of 1905, Duluth was said to be home to the most millionaires per capita in the United States. In 1907, U.S. Steel announced that it would build a $ 5 million plant in the area. Although steel production did not begin until 1915, predictions held that Duluth's population would rise to 200,000–300,000. Along with
5292-457: The Native American peoples to a number of small reservations. Interest in the area was piqued in the 1850s by rumors of copper mining . A government land survey in 1852, followed by a treaty with local tribes in 1854, secured wilderness for gold-seeking explorers, sparked a land rush , and led to the development of iron ore mining in the area. The 1854 Ojibwe Land Cession Treaty would force
5400-523: The Ojibwe Indians there. Henry Wadsworth Longfellow based the Song of Hiawatha , his epic poem relating the fictional adventures of an Ojibwe warrior named Hiawatha and the tragedy of his love for Minnehaha, a Dakota woman, on Schoolcraft's writings. Natives signed two Treaties of Fond du Lac with the United States in the present neighborhood of Fond du Lac in 1826 and 1847, in which the Ojibwe ceded land to
5508-618: The Ojibwe Nation came together and proceeded to their "Seventh Stopping Place", near the present city of La Pointe, Wisconsin . The "Stopping Places" were the places the Native Americans occupied during their westward migration as the Europeans overran their territory. Several factors brought fur traders to the Great Lakes in the early 17th century. The fashion for beaver hats in Europe generated demand for pelts. French trade for beaver in
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#17328587349465616-589: The Ojibwe onto what are now known as the Fond du Lac and Grand Portage Reservations, though some land rights such as hunting and fishing were retained. Around the same time, newly constructed channels and locks in the East permitted large ships to access the area. A road connecting Duluth to the Twin Cities was also constructed. Eleven small towns on both sides of the St. Louis River were formed, establishing Duluth's roots as
5724-414: The United States from 5 kilowatts (kW) to 25 kW. Around the time of World War I, American windmill makers were producing 100,000 farm windmills each year, mostly for water-pumping. By the 1930s, use of wind turbines in rural areas was declining as the distribution system extended to those areas. A forerunner of modern horizontal-axis wind generators was in service at Yalta , USSR, in 1931. This
5832-460: The Woodland District... In most cases, families which lost their homes also lost most or all of their furniture and personal belongings, the limited time and transportation facilities affording little opportunity for saving anything but human life." The National Guard unit based in Duluth was mobilized in a heroic effort to battle the fire and assist victims, but the troops were overwhelmed by
5940-443: The air arrives at the turbine. The maximum theoretical power output of a wind machine is thus 16 ⁄ 27 times the rate at which kinetic energy of the air arrives at the effective disk area of the machine. If the effective area of the disk is A, and the wind velocity v, the maximum theoretical power output P is: where ρ is the air density . Wind-to-rotor efficiency (including rotor blade friction and drag ) are among
6048-412: The beginning of the 21st century, Duluth has become a regional center for banking, retail shopping, and medical care for northern Minnesota, northern Wisconsin, and northwestern Michigan. It is estimated that more than 8,000 jobs in Duluth are directly related to its two hospitals. Arts and entertainment offerings, as well as year-round recreation and the natural environment, have contributed to expansion of
6156-430: The blade, the pulsating torque generated by some rotor designs on the drive train, and the difficulty of modelling the wind flow accurately and hence the challenges of analysing and designing the rotor prior to fabricating a prototype. When a turbine is mounted on a rooftop the building generally redirects wind over the roof and this can double the wind speed at the turbine. If the height of a rooftop mounted turbine tower
6264-570: The blades snapped off. The unit was not repaired, because of a shortage of materials during the war. The first utility grid-connected wind turbine to operate in the UK was built by John Brown & Company in 1951 in the Orkney Islands . In the early 1970s, however, anti-nuclear protests in Denmark spurred artisan mechanics to develop microturbines of 22 kW despite declines in the industry. Organizing owners into associations and co-operatives led to
6372-414: The blades upwind of the tower ( i.e. blades facing the incoming wind) produce the overwhelming majority of wind power in the world today. These turbines have the main rotor shaft and electrical generator at the top of a tower and must be pointed into the wind. Small turbines are pointed by a simple wind vane , while large turbines generally use a wind sensor coupled with a yaw system. Most have
6480-511: The bridge was fellow World War II veteran Amardo J. "Marty" Romano. The bridge was originally to be named Arrowhead Bridge , after the old wood trestle– bascule bridge it replaced. Construction on the bridge began in 1979, and it was opened on October 25, 1984. The bridge was one of the largest public works projects undertaken by the state of Wisconsin. Ayres Associates, an architectural/engineering company based in Eau Claire, Wisconsin , managed
6588-486: The city has grown, its populace has tended to hug Lake Superior's shoreline, so Duluth is primarily a southwest–northeast city. The considerable development on the hill has given Duluth many steep streets. Some neighborhoods, such as Piedmont Heights and Bayview Heights , are atop the hill with scenic views of the city. Skyline Parkway is a scenic roadway that extends from Becks Road above the Gary – New Duluth neighborhood near
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#17328587349466696-544: The city is a hub for cargo shipping. The population was 86,697 at the 2020 census , making it Minnesota's fifth-largest city . Duluth forms a metropolitan area with neighboring Superior, Wisconsin , called the Twin Ports . It is south of the Iron Range and the Boundary Waters Canoe Area Wilderness . It is named after Daniel Greysolon, Sieur du Lhut , the area's first known European explorer. Duluth
6804-493: The city of Superior , Wisconsin , is the largest freshwater baymouth bar in the world at a total of 10 miles (16 km). Duluth's topography is dominated by a steep hillside that climbs from Lake Superior to high inland elevations. Duluth has been called "the San Francisco of the Midwest," alluding to San Francisco 's similar water-to-hilltop topography. This similarity was most evident before World War II, when Duluth had
6912-536: The community be called "Duluth" instead, and townspeople agreed. Proctor Knott is sometimes credited with characterizing Duluth as the "zenith city of the unsalted seas," but the honor for that coinage belongs to journalist Thomas Preston Foster, speaking at a Fourth of July picnic in 1868. During the 20th century, the Port of Duluth was, for a time, the busiest port in the United States, surpassing even New York City in gross tonnage. Lake freighters carried iron ore through
7020-572: The company catalog totaled 2,390 pages by 1913. The Duluth Showcase Company, which later became the Duluth Refrigerator Company and then the Coolerator Company, was established in 1908. The Universal Atlas Cement Company, which made cement from the slag byproduct of the steel plant, began operations in 1917. Because of its numerous jobs in mining and industry, the city was a destination for large waves of immigrants from Europe during
7128-486: The contiguous US behind International Falls ), falling to or below 0 °F (−18 °C) on 38 nights and bringing consistent snow cover from late November to early April. Winter storms that pass south or east of Duluth can often set up easterly or northeasterly flow, which leads to occasional upslope lake-effect snow events that bring 1 foot (30 cm) or more of snow to the city while areas 50 miles (80 km) inland receive considerably less. The average annual snowfall
7236-495: The early 20th century. It became the center of one of the largest Finnish communities in the world outside Finland. For decades, a Finnish-language daily newspaper, Päivälehti, was published in the city, named after the former Grand Duchy of Finland 's pro-independence liberal paper . The Finnish community of Industrial Workers of the World (IWW) members published a widely read labor newspaper Industrialisti . From 1907 to 1941,
7344-448: The edge of the city's western neighborhoods. Many of these sites, filled with legacy pollutants due to previous industrial use, have been or are in the process of being restored by the EPA, with several developments, such as Pier B Resort and Hotel, demonstrating the revitalization opportunity of these former industrial spaces. Other efforts to reclaim waterfront space in Duluth have been led by
7452-414: The energy converted to electrical energy. Since outgoing wind will still possess some kinetic energy, there must be a maximum proportion of the input energy that is available to be converted to electrical energy. Accordingly, Betz's law gives the maximal achievable extraction of wind power by a wind turbine, known as Betz's coefficient, as 16 ⁄ 27 (59.3%) of the rate at which the kinetic energy of
7560-407: The enormity of the fire. Retired Duluth News Tribune columnist and journalist Jim Heffernan writes that his mother "recalled an overnight vigil watching out the window of their small home on lower Piedmont Avenue with her father, her younger sisters having gone to sleep, ready to be evacuated to the waterfront should the need arise. The fire never made it that far down the hill, but devastated what
7668-552: The event with a memorial. The Clayton Jackson McGhie Memorial, which includes a corner wall and plaza, was dedicated in 2003. It includes three 7-foot (2.1 m)-tall bronze statues of the three men. The CJMM Committee continues to work for racial justice through educational outreach, community forums, and scholarships for youth. In 1918, the Cloquet Fire (named for the nearby city of Cloquet ) burned across Carlton and southern St. Louis counties, destroying dozens of communities in
7776-405: The event. Community members from many different groups began to come together for reflection and education. The men's unmarked graves were located and in 1991, gravestones were erected with funding from a local church. Vigils were held at the intersection where the men were lynched. In 2000, a grassroots committee was formed, and began to offer speakers to groups and schools. It decided to commemorate
7884-453: The factors affecting the final price of wind power. Further inefficiencies, such as gearbox , generator, and converter losses, reduce the power delivered by a wind turbine. To protect components from undue wear, extracted power is held constant above the rated operating speed as theoretical power increases as the cube of wind speed, further reducing theoretical efficiency. In 2001, commercial utility-connected turbines delivered 75% to 80% of
7992-998: The generator, is 15.24 meters (50.0 ft) and weighs around 300 tons. Due to data transmission problems, structural health monitoring of wind turbines is usually performed using several accelerometers and strain gages attached to the nacelle to monitor the gearbox and equipment. Currently, digital image correlation and stereophotogrammetry are used to measure dynamics of wind turbine blades. These methods usually measure displacement and strain to identify location of defects. Dynamic characteristics of non-rotating wind turbines have been measured using digital image correlation and photogrammetry. Three dimensional point tracking has also been used to measure rotating dynamics of wind turbines. Generally, efficiency increases along with turbine blade lengths. The blades must be stiff, strong, durable, light and resistant to fatigue. Materials with these properties include composites such as polyester and epoxy, while glass fiber and carbon fiber have been used for
8100-565: The goods being shipped through the Duluth-Superior port have shifted to reflect a changing economy. In recent decades, declines in the shipment of coal and iron ore have been met by increases in the shipment of wind turbine components and multimodal shipping containers. According to the United States Census Bureau , the city has a total area of 80.168 square miles (207.63 km ), of which 71.658 square miles (185.59 km )
8208-411: The higher the wind velocity on average. A windbreak can also increase the wind velocity near the turbine. Wind turbines can rotate about either a horizontal or a vertical axis, the former being both older and more common. They can also include blades or be bladeless. Household-size vertical designs produce less power and are less common. Large three-bladed horizontal-axis wind turbines (HAWT) with
8316-416: The highway to run through tunnels, which allowed preservation of Fitger's Brewery, Sir Ben's Tavern, Leif Erikson Park, and Duluth's Rose Garden. Rock used from the interstate project was used to create an extensive new beach along Lake Superior, along which the city's Lakewalk was built. With the decline of the city's industrial core, the local economic focus gradually shifted to tourism . The downtown area
8424-662: The igneous rocks of the rift is exposed near Fond du Lac . At one time a large number of quarries produced the stone, sold as Fond du Lac or Lake Superior brownstone . It was widely used in Duluth buildings and also shipped to Minneapolis, Chicago, and Milwaukee, where it was also used extensively. The weathered sandstone forms the sandy lake bottom and shores of Park Point. Duluth has a humid continental climate ( Köppen Dfb ), slightly moderated by its proximity to Lake Superior. Winters are long, snowy, and very cold, normally seeing maximum temperatures remaining at or below 32 °F (0 °C) on 100 days (the second-most of any city in
8532-804: The lobbying of the government and utilities and provided incentives for larger turbines throughout the 1980s and later. Local activists in Germany, nascent turbine manufacturers in Spain, and large investors in the United States in the early 1990s then lobbied for policies that stimulated the industry in those countries. It has been argued that expanding the use of wind power will lead to increasing geopolitical competition over critical materials for wind turbines, such as rare earth elements neodymium , praseodymium , and dysprosium . However, this perspective has been critically dismissed for failing to relay how most wind turbines do not use permanent magnets and for underestimating
8640-461: The lower St. Lawrence River led to the depletion of the animals in the region by the late 1630s, so the French searched farther west for new resources and new routes, making alliances with the Native Americans along the way to trap and deliver their furs. Étienne Brûlé is credited with the European discovery of Lake Superior before 1620. Pierre-Esprit Radisson and Médard des Groseilliers explored
8748-412: The neighborhood's revitalization, many developers are also investing in housing projects in anticipation of further growth. Duluth's prominence as a port city gave it an economic advantage in its early years, but as various industries began to wane, new efforts to reclaim areas of the waterfront for public use emerged. Notable among them is the reclamation of the St. Louis River corridor, which runs along
8856-493: The north and with the Mississippi River to the south. After creating a powerful monopoly , Astor got out of the business about 1830, as the trade was declining. But active trade carried on until the failure of the fur trade in the 1840s. European fashions changed, and many American areas were getting over-trapped, with game declining. In 1832, Henry Schoolcraft visited the Fond du Lac area and wrote of his experiences with
8964-562: The other half saw a production decrease of 1.2% per year. In general, more stable and constant weather conditions (most notably wind speed) result in an average of 15% greater efficiency than that of a wind turbine in unstable weather conditions, thus allowing up to a 7% increase in wind speed under stable conditions. This is due to a faster recovery wake and greater flow entrainment that occur in conditions of higher atmospheric stability. However, wind turbine wakes have been found to recover faster under unstable atmospheric conditions as opposed to
9072-439: The power of economic incentives for the expanded production of these minerals. Wind Power Density (WPD) is a quantitative measure of wind energy available at any location. It is the mean annual power available per square meter of swept area of a turbine, and is calculated for different heights above ground. Calculation of wind power density includes the effect of wind velocity and air density. Wind turbines are classified by
9180-698: The project and designed the 1.5-mile (2.4 km) length of approach bridges. The Wisconsin Department of Transportation designed the channel span (tied arch). Its central suspension section is made of Japanese steel. In 2007, the Bong Bridge won a Wonders of Wisconsin Engineering Award from the American Council of Engineering Companies , Wisconsin Chapter, which was celebrating its 50th anniversary. The bridge
9288-469: The rare earth materials required, these gearless turbines are sometimes preferred over gearbox generators because they "eliminate the gear-speed increaser, which is susceptible to significant accumulated fatigue torque loading, related reliability issues, and maintenance costs". There is also the pseudo direct drive mechanism, which has some advantages over the permanent magnet direct drive mechanism. Most horizontal axis turbines have their rotors upwind of
9396-435: The reinforcing. Construction may involve manual layup or injection molding. Retrofitting existing turbines with larger blades reduces the task and risks of redesign. As of 2021, the longest blade was 115.5 m (379 ft), producing 15 MW. Blades usually last around 20 years, the typical lifespan of a wind turbine. Materials commonly used in wind turbine blades are described below. The stiffness of composites
9504-597: The river to accommodate maritime traffic in a 400-foot-wide navigation channel. The Bong Bridge is one of three bridges connecting Duluth and Superior. A through-arch bridge downstream from the Bong -- the John A. Blatnik Bridge -- carries Interstate 535 (I-535) over the water. The third bridge is the Oliver Bridge , which connects the Gary – New Duluth neighborhood in Duluth, Minnesota with
9612-436: The rotor. Solidity is measured by the blade area divided by the rotor area. A subtype of Darrieus turbine with straight, as opposed to curved, blades. The cycloturbine variety has variable pitch to reduce the torque pulsation and is self-starting. The advantages of variable pitch are high starting torque; a wide, relatively flat torque curve; a higher coefficient of performance ; more efficient operation in turbulent winds; and
9720-420: The supporting tower. Downwind machines have been built, because they don't need an additional mechanism for keeping them in line with the wind. In high winds, downwind blades can also be designed to bend more than upwind ones, which reduces their swept area and thus their wind resistance, mitigating risk during gales. Despite these advantages, upwind designs are preferred, because the pulsing change in loading from
9828-600: The tourist industry. Some 3.5 million visitors each year contribute more than $ 400 million to the local economy. More recently a collection of like-minded businesses in Lincoln Park , an old rundown blue-collar neighborhood with high unemployment and poverty rates, was cultivated by a group of entrepreneurs who have begun rebuilding and revitalizing the area. Since 2014, at least 25 commercial real estate transactions have occurred and 17 businesses have opened, including restaurants, breweries, coffee shops and artist studios. Due to
9936-486: The utility supplier via the electrical grid . Wind turbines are manufactured in a wide range of sizes, with either horizontal or vertical axes, though horizontal is most common. The windwheel of Hero of Alexandria (10–70 CE) marks one of the first recorded instances of wind powering a machine. However, the first known practical wind power plants were built in Sistan , an Eastern province of Persia (now Iran), from
10044-449: The village of Oliver, Wisconsin. The bridge is 1,889 feet (576 m) long[1] and is principally of steel truss construction. The upper deck carries a single track rail line and a lower deck carries the road connecting Wisconsin Highway 105 to Minnesota State Highway 39. The bridge's namesake, Richard Ira Bong , was a pilot in the U.S. Army Air Corps during World War II who was named the United States' all-time " Ace of Aces ". The designer of
10152-491: The visual appeal. Wind turbine design is a careful balance of cost, energy output, and fatigue life. Wind turbines convert wind energy to electrical energy for distribution. Conventional horizontal axis turbines can be divided into three components: A 1.5 ( MW ) wind turbine of a type frequently seen in the United States has a tower 80 meters (260 ft) high. The rotor assembly (blades and hub) measures about 80 meters (260 ft) in diameter. The nacelle , which contains
10260-693: The western end of the city to the Lester Park neighborhood on the east side. It crosses nearly Duluth's entire length and affords views of Lake Superior, the Aerial Lift Bridge, Canal Park, and the many industries that inhabit the largest inland port. A developing part of the city is the Miller Hill Mall area and the adjacent big-box retailer shopping strips "over the hill" along the Miller Trunk Highway corridor. The 2009–10 road reconstruction project in Duluth's Miller Hill area improved movement through
10368-514: The wind as each blade passes behind the supporting tower can cause damage to the turbine. Turbines used in wind farms for commercial production of electric power are usually three-bladed. These have low torque ripple , which contributes to good reliability. The blades are usually colored white for daytime visibility by aircraft and range in length from 20 to 80 meters (66 to 262 ft). The size and height of turbines increase year by year. Offshore wind turbines are built up to 8 MW today and have
10476-406: The wind speed they are designed for, from class I to class III, with A to C referring to the turbulence intensity of the wind. Conservation of mass requires that the mass of air entering and exiting a turbine must be equal. Likewise, the conservation of energy requires the energy given to the turbine from incoming wind to be equal to that of the combination of the energy in the outgoing wind and
10584-466: Was a 100 kW generator on a 30-meter (98 ft) tower, connected to the local 6.3 kV distribution system. It was reported to have an annual capacity factor of 32 percent, not much different from current wind machines. In the autumn of 1941, the first megawatt-class wind turbine was synchronized to a utility grid in Vermont . The Smith–Putnam wind turbine only ran for about five years before one of
10692-851: Was able to build the first automatically operated wind turbine after consulting local University professors and his colleagues Jacob S. Gibbs and Brinsley Coleberd and successfully getting the blueprints peer-reviewed for electricity production. Although Blyth's turbine was considered uneconomical in the United Kingdom, electricity generation by wind turbines was more cost effective in countries with widely scattered populations. In Denmark by 1900, there were about 2500 windmills for mechanical loads such as pumps and mills, producing an estimated combined peak power of about 30 megawatts (MW). The largest machines were on 24-metre (79 ft) towers with four-bladed 23-metre (75 ft) diameter rotors. By 1908, there were 72 wind-driven electric generators operating in
10800-565: Was ever constructed in the country. In 1929–30, the span was converted to a vertical-lift bridge (also rather uncommon). The bridge was added to the National Register of Historic Places in 1973. In 1916, after Europe had entered the Great War (World War I), a shipyard was constructed on the St. Louis River. A new workers neighborhood, today known as Riverside, developed around the large operation. Similar industrial expansions took place during
10908-505: Was found two weeks later hanging in a tree in Duluth's Lester Park. Another lynching in Duluth occurred on June 15, 1920, when three innocent black male circus workers: Elias Clayton, Elmer Jackson, and Isaac McGhie, were attacked by a white mob and hanged after purportedly raping a teenage white girl. The Duluth lynchings took place on First Street and Second Avenue East. In the late 20th century, journalist Michael Fedo wrote The Lynchings in Duluth (1970), which began to raise awareness of
11016-631: Was home to several historic immigrant neighborhoods, including Little Italy. Today, people of Scandinavian descent constitute a strong plurality of Duluth's population, accounting for more than one third of the residents identifying European ancestry. In September 1918, a group calling itself the Knights of Liberty dragged Finnish immigrant Olli Kinkkonen from his boarding house, tarred and feathered him, and lynched him. Kinkkonen did not want to fight in World War I and had planned to return to Finland. His body
11124-552: Was installed by the Austrian Josef Friedländer at the Vienna International Electrical Exhibition in 1883. It was a Halladay windmill for driving a dynamo . Friedländer's 6.6 m (22 ft) diameter Halladay "wind motor" was supplied by U.S. Wind Engine & Pump Co. of Batavia , Illinois . The 3.7 kW (5 hp) windmill drove a dynamo at ground level that fed electricity into
11232-469: Was obtained from a stream that emptied into Lake Superior that came to be called Brewery Creek, as it is still known today. While the brewery "was not a pecuniary success", a few decades later it became the Fitger Brewing Company . The opening of the canal at Sault Ste. Marie in 1855 and the contemporaneous announcement of the railroads' approach had made Duluth the only port with access to both
11340-510: Was renovated to emphasize its pedestrian character: streets were paved with red brick and skywalks and retail shops were added. The city and developers worked with the area's unique architectural character, converting old warehouses along the waterfront into cafés, shops, restaurants, and hotels. Combined with the new rock beach and Lakewalk, these changes developed the new Canal Park as a tourism-oriented district. Duluth's population, which had declined since 1960, stabilized at around 85,000. At
11448-531: Was shipped east to mills in Ohio, a trade continuing into the 20th century. Early doubts about the Duluth area's potential were voiced in "The Untold Delights of Duluth," a speech U.S. Representative J. Proctor Knott of Kentucky gave in the U.S. House of Representatives on January 27, 1871. His speech opposing the St. Croix and Superior Land Grant lampooned Western boosterism , portraying Duluth as an Eden in fantastically florid terms. The speech has been reprinted in collections of folklore and humorous speeches and
11556-478: Was the fastest-growing city in the country and was expected to surpass Chicago in only a few years. When Jay Cooke , a wealthy Philadelphia land speculator, convinced the Lake Superior and Mississippi Railroad to create an extension from St. Paul to Duluth, the railroad opened areas due north and west of Lake Superior to iron ore mining. Duluth's population on New Year's Day of 1869 consisted of 14 families; by
11664-419: Was the scene of a 16-vehicle pile-up on January 27, 2005, in which 10 people were hospitalized and a baby was given an emergency delivery but subsequently died. Duluth, Minnesota Duluth ( / d ə ˈ l uː θ / də- LOOTH ) is a port city in the U.S. state of Minnesota and the county seat of St. Louis County . Located on Lake Superior in Minnesota's Arrowhead Region ,
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