Browsing by Subject "Wind turbines"

Now showing 1 - 3 of 3
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    Development of a Comprehensive Conservation Strategy for the North Shore Highlands Region of Minnesota in the Context of Future Wind Power Development
    (University of Minnesota Duluth, 2012) Peterson, Anna; Niemi, Gerald J
    Each autumn, millions of birds migrate from their breeding grounds in the northern hemisphere to wintering areas in the continental United States, Mexico, Central America, and South America (Rich 2004, Bildstein 2006). The North Shore Highlands parallels the Lake Superior shoreline from Duluth through Grand Portage, Minnesota to the US border with Canada. This region’s prominent ridgelines and Lake Superior coastline funnel migrating birds into this migration corridor (Hofslund 1966, Mueller and Berger 1967, Bildstein 2006). As a result, the North Shore Highlands hosts the largest migratory route for birds of prey in Minnesota and is among the highest in the US. In addition, recent data suggest that the numbers of non-raptor bird species moving along the north shore of Lake Superior are orders of magnitude larger than those for raptors. Migration periods constitute a critical life-stage for these birds as mortality rates may be higher during migration than during breeding or over wintering periods (Sillett and Holmes 2002, Smith and Moore 2003). Large bodies of water and other major topographical features cause a nonrandom distribution of migrating birds on the landscape in both periods of active flight and rest (Goodrich and Smith 2008). Landscape features that define the North Shore Highlands (Lake Superior, ridgelines, river valleys) result in a major congregation of migratory birds (raptors and passerines) that are both actively flying and resting within the region. With the current emphasis on renewable energy (Great Lakes Commission 2011), the North Shore Highlands region has become a focal point for potential wind power, with many plans already in progress (Mageau et al. 2008). Besides wind turbines there is also increased activity in the development of communication towers in the region. The North Shore Highlands region is recognized as one of the top tourist destinations in Minnesota and the upper Midwestern US. Over the past twenty years, the area has experienced increased developmental pressure from recreation, tourism, and exurban housing (MNDNR 2006). Conservation strategies aimed at the protection of migratory birds are incomplete without the focus on migratory bird flyway and stopover habitat preservation (Petit 2000, Mehlman et al. 2005). To develop conservation strategies to protect en route migratory birds within this region, there is a need to understand the cues by which migrants choose migratory flight paths and stopover habitats (Ewert et al. 2011, Buler et al. 2007, Bonter et al. 2009). Our overall goal is to provide data and mapping products that will contribute to a comprehensive conservation plan for migratory birds highlighting the potential risks of wind energy development within the North Shore Highlands region. We have worked closely with several community groups in the region (e.g., Grand Portage Indian Reservation, Cook County Local Energy Project, and Lutsen Mountains Resort) who have expressed an interest in wind energy development. Our purpose will be to eliminate or minimize interactions with migratory birds if wind turbines are placed in the North Shore Highlands region.
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    North Shore bat activity and habitat use
    (University of Minnesota Duluth, 2011) Abel, Rebecca; Moen, Ronald
    Wind power development is an emerging issue in northeastern Minnesota. A recent Coastal Zone Management Program (CZMP) study showed strong potential for wind energy along the North Shore, even though wind speed maps indicate that northeastern Minnesota has less wind potential than other parts of the state. There are seven bat species in Minnesota, and all of them could be affected by wind power development. Baseline data on bat distribution and habitat use is essential for bat conservation. Little information exists on bats in the southern boreal forests of the Midwest. We measured summer bat habitat use and foraging activity at aquatic, linear corridor, and interior forest sites with bat detectors in deciduous, mixed-wood, and coniferous forests in northeastern Minnesota. We used three common acoustic bat activity indices to quantify acoustic bat data and examined the indices to determine how differences among activity indices influence statistical inferences of bat activity. We measured the effects of relative insect abundance and degree of vegetation density on bat activity. Bat detectors recorded 7,666 identifiable bat calls during 1,440 detector hours in 2009 and 8,554 bat calls during 930 detector hours in 2010. Bat activity was dominated by Myotis species (Myotis lucifugus and M. septentrionalis) and Lasionycteris noctivagans. Activity was concentrated at aquatic and linear corridor microsites, regardless of forest cover type. However, bats foraged at similar rates in each microsite type. Bat activity and foraging activity occurred earlier at night at interior forest sites relative to aquatic and linear corridor sites, suggesting that interior forest is used by bats to forage as they leave day roosts. The three acoustic activity indices we used resulted in similar conclusions of habitat use by bats, despite different biases of each. Bats would generally be flying in low wind conditions, especially when foraging. If wind turbines were deployed along the North Shore, we recommend monitoring bat activity to document potential effects at the site(s). However, because all bat species were present along the entire north shore of Lake Superior inland throughout the Coastal Zone area, wind turbines are unlikely to have a population level effect on bats unless many are installed.
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    Preview control for wind turbines
    (2013-08) Ozdemir, Ahmet Arda
    The success of wind power as a renewable energy source depends on its cost of energy. Wind turbine control has attracted much attention in the controls community due to its potential impact on the cost of wind power. However, novel methods in the literature have not transitioned well to industry. This is because the potential cost benefits of these methods are not well understood. There is a need for basic research to address this issue. This thesis is one step toward transitioning of advanced control methods in literature to the industry. Particularly, we aim to understand the limits of performance. The potential performance improvements of the advanced methods should be large enough to justify their cost and complexity. We investigate the optimal trade-offs between multiple turbine performance goals. We also explore the use of a novel wind preview sensor in closed-loop control laws. The impact of this novel sensor on the optimal turbine performance is investigated. The specific contributions of this thesis can be grouped in three categories. First, we present a preliminary, nonlinear optimization based controller design and analysis framework. This framework can simplify the design of the advanced multivariable controllers for nonlinear systems. It can also be used to investigate the optimal design trade-offs between nonlinear performance constraints and objectives. Second, engineering insight is provided into turbine design trade-offs. Third, we provide mathematical tools that quantify the limits of turbine performance in presence of preview wind measurements. Optimization tools that can analyze the trade-off between preview time and operating condition dependent turbine performance objectives are presented. In low wind speeds, our results show that simultaneous power capture improvements and structural load reductions can be obtained. In high wind speeds, a short amount of preview wind information can be used to overcome the fundamental performance limitations imposed by actuator rate constraints. We provide analytical formulas that quantify these preview time requirements and performance limitations. A convex optimization framework is also presented for the analysis of extreme operating conditions that are defined by deterministic wind disturbance trajectories.