Browsing by Subject "Wind"

Now showing 1 - 7 of 7
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    Cost of wind energy: comparing distant wind resources to local resources in the midwestern United States.
    (Environ Sci Technol, 2010-11-15) Hoppock, David C; Patiño-Echeverri, Dalia
    The best wind sites in the United States are often located far from electricity demand centers and lack transmission access. Local sites that have lower quality wind resources but do not require as much power transmission capacity are an alternative to distant wind resources. In this paper, we explore the trade-offs between developing new wind generation at local sites and installing wind farms at remote sites. We first examine the general relationship between the high capital costs required for local wind development and the relatively lower capital costs required to install a wind farm capable of generating the same electrical output at a remote site,with the results representing the maximum amount an investor should be willing to pay for transmission access. We suggest that this analysis can be used as a first step in comparing potential wind resources to meet a state renewable portfolio standard (RPS). To illustrate, we compare the cost of local wind (∼50 km from the load) to the cost of distant wind requiring new transmission (∼550-750 km from the load) to meet the Illinois RPS. We find that local, lower capacity factor wind sites are the lowest cost option for meeting the Illinois RPS if new long distance transmission is required to access distant, higher capacity factor wind resources. If higher capacity wind sites can be connected to the existing grid at minimal cost, in many cases they will have lower costs.
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    Decision rules of blue crab (Callinectes sapidus) movement in wind-driven systems
    (2015-04-24) Chen, Julia
    Blue crabs (Callinectes sapidus) are the most economically valuable fishery in North Carolina, and the commercial harvest is mainly from the Albemarle-Pamlico Estuarine System (APES). Because of small inlets which restrict ocean tidal forcing in addition to large expanses of shallow water, circulation in the APES is primarily wind-driven. While much is known about how crabs move in tidally-dominated systems where movements are based upon selective tidal-stream transport, crab movements in wind-driven systems, and their response to environmental factors, remain poorly understood. This study aims to increase understanding of environmental controls on blue crab movements in order to inform management of crab resources in wind-driven systems. We studied crab movements in Lake Mattamuskeet National Wildlife Refuge, a 40,000-acre shallow, wind-driven system within the APES. During October 2014, free ranging crabs were tracked using radio frequency identification (RFID) tags and an antenna array deployed along the Central Canal connecting the lake to Pamlico Sound. Colocated and simultaneous meteorological and physical oceanographic data were collected to understand environmental drivers that may affect crab movements. Analyses of these data indicate: 1) a significant net export of blue crabs from the lake to the sound; the drivers of that export remain unclear; 2) crab movements coincided with the direction of water flow in the canal, and 3) at small-scales, crabs were able to move against the water flow. These results suggest that there is a fall migration, during which crabs move from the lake to the sound, and at a relatively constant rate that is slower than the mean water flow. If crabs are to move out of the lake at this time it is essential to open water control structures in order to facilitate migration. This is particularly important for the females, who because of their large size may contribute disproportionately large amounts of larvae to the Pamlico Sound broodstock. Crabs in the larger fishery may also move toward higher salinity water if they behave similarly to those studied here.
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    Dust in the wind: How climate variables and volcanic dust affect rates of tooth wear in Central American howling monkeys.
    (Am J Phys Anthropol, 2016-02) Spradley, Jackson P; Glander, Kenneth E; Kay, Richard F
    OBJECTIVES: Two factors have been considered important contributors to tooth wear: dietary abrasives in plant foods themselves and mineral particles adhering to ingested food. Each factor limits the functional life of teeth. Cross-population studies of wear rates in a single species living in different habitats may point to the relative contributions of each factor. MATERIALS AND METHODS: We examine macroscopic dental wear in populations of Alouatta palliata (Gray, 1849) from Costa Rica (115 specimens), Panama (19), and Nicaragua (56). The sites differ in mean annual precipitation, with the Panamanian sites receiving more than twice the precipitation of those in Costa Rica or Nicaragua (∼3,500 mm vs. ∼1,500 mm). Additionally, many of the Nicaraguan specimens were collected downwind of active plinian volcanoes. Molar wear is expressed as the ratio of exposed dentin area to tooth area; premolar wear was scored using a ranking system. RESULTS: Despite substantial variation in environmental variables and the added presence of ash in some environments, molar wear rates do not differ significantly among the populations. Premolar wear, however, is greater in individuals collected downwind from active volcanoes compared with those living in environments that did not experience ash-fall. DISCUSSION: Volcanic ash seems to be an important contributor to anterior tooth wear but less so in molar wear. That wear is not found uniformly across the tooth row may be related to malformation in the premolars due to fluorosis. A surge of fluoride accompanying the volcanic ash may differentially affect the premolars as the molars fully mineralize early in the life of Alouatta.
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    Estimation of in-canopy ammonia sources and sinks in a fertilized Zea mays field.
    (Environ Sci Technol, 2010-03-01) Bash, JO; Walker, JT; Katul, GG; Jones, MR; Nemitz, E; Robarg, WP
    An analytical model was developed to describe in-canopy vertical distribution of ammonia (NH(3)) sources and sinks and vertical fluxes in a fertilized agricultural setting using measured in-canopy mean NH(3) concentration and wind speed profiles. This model was applied to quantify in-canopy air-surface exchange rates and above-canopy NH(3) fluxes in a fertilized corn (Zea mays) field. Modeled air-canopy NH(3) fluxes agreed well with independent above-canopy flux estimates. Based on the model results, the urea fertilized soil surface was a consistent source of NH(3) one month following the fertilizer application, whereas the vegetation canopy was typically a net NH(3) sink with the lower portion of the canopy being a constant sink. The model results suggested that the canopy was a sink for some 70% of the estimated soil NH(3) emissions. A logical conclusion is that parametrization of within-canopy processes in air quality models are necessary to explore the impact of agricultural field level management practices on regional air quality. Moreover, there are agronomic and environmental benefits to timing liquid fertilizer applications as close to canopy closure as possible. Finally, given the large within-canopy mean NH(3) concentration gradients in such agricultural settings, a discussion about the suitability of the proposed model is also presented.
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    Predictive Analysis of Global Renewable Energy and Infrastructure Growth in Developed, Developing and Emerging Markets
    (2011-12-09) Nolan, Mike; Naftel, Jackson IV; Reaves, Patrick
    The most attractive markets for renewable energy investment are shifting from the developed world to emerging economies. Among the most prominent emerging economies, China, India, and Brazil have become three of the most important global investment markets, and the role of renewable energy in each country is becoming increasingly important. At the same time smart grid advancements are creating above average returns in developed countries such as the United States and Germany. This report analyzes renewable energy investment opportunities in USA, Germany, Brazil, China, India and Indonesia. In an effort to quantify, compare, and rank our findings for each country, our team developed a simple model to weight each metric based on each country’s policies, infrastructure, resources, and electric power market as they relate to the attractiveness of renewable energy investment. We then modified the evaluation to incorporate our client’s qualitative weighting for each evaluation criteria. After a detailed analysis was performed, the following 3 recommendations can be made: 1. India, China and Germany have created a favorable economic and policy environment for solar investment; however, given the global nature of the industry and current uncertainty in the marketplace, we do not recommend investing in solar at this time. 2. Due to substantial line losses in India, and likely development of long-distance transmission in China and Brazil, our team foresees a substantial investment opportunity in the global transmission and distribution value chain. We recommend one discrete investment opportunity in one of India’s state-owned electric supply companies, the Calcutta Electric Supply Company (CESC), as well as smart grid component suppliers such as ABB and Thomas and Betts. 3. Growth in wind power will likely continue in Germany, specifically offshore wind. However, until the German government takes a stronger stance on its policy towards natural gas our team recommends waiting to invest in the German wind industry as the natural gas market may be a serious threat to the wind industry.
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    THE ECONOMIC FEASIBILITY OF POWER PRODUCTION FROM UTILITY SCALE WIND FARMS AT OBERLIN COLLEGE
    (2010-04-30T17:04:29Z) Roth, Michael B.
    The State of Ohio receives 90% of its electricity from coal power plants. The City of Oberlin’s power provider, Oberlin Municipal Light and Power Systems (OMLPS), is facing a 70% net annual shortfall in electric supply starting in January of 2013. Oberlin College is OMLPS’s biggest customer and has also committed to becoming climate neutral. This study assesses the economic viability of meeting Oberlin College and OMLPS’s future electric demand via a local utility-scaled wind farm. This study uses a years worth of wind data collected on a 160-foot monitoring tower along with two sets of wind data that are extrapolated to turbine hub height in order to predict the annual electric output from a number of different wind turbines. Several different installation cost scenarios are used to predict the price of electricity from these turbines at varying hub heights. The results section of this analysis outlines the required price per kWh for each turbine model that would need to be charged in order meet annual payments on a 15-year 5% interest loan equal to the installation cost of a specific wind turbine. The paper specifically analyses a 4.5 MW wind farm comprised of three GE 1.5 XLE wind turbines at an installation cost of $2.15 million per MW. The analysis uses three sets of wind speeds in order to predict annual electric production: 50m observed data, a conservative extrapolation, and a more optimistic extrapolation. For the GE 4.5 MW wind farm, prior to the Federal Production Tax Credit of $0.021 per kWh, prices range from $0.10 to $0.15 per kWh. Considering that Oberlin College currently pays $0.09 per kWh, it is possible that a wind farm could save the college money on electric bills while reducing the carbon intensity of its electricity at a profit.
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    The Presence of Great White Sharks: Associations with Environmental Factors
    (2011-04-28) Dove, Karen
    The white shark (Carcharodon carcharias) can be regarded as one of the greatest ambush predators on Earth. White sharks have learned the best techniques, places, and times to hunt to maximize their success rate. They are aware of environmental conditions that affect their chances of success. This paper looks at the frequency of white shark sightings compared to wind speeds in Mossel Bay, South Africa and wind’s effect on white shark hunting behavior. The hypothesis is that more sharks will be hunting during high wind speeds because this decreases water visibility and increases swell height, two known environmental factors that aid in ambush predation. Ambush predators like the white shark benefit from poor water visibility and large swells which put their prey at a visual disadvantage. Sharks in Mossel Bay must rely on water visibility more than water depth to conceal their presence because it is relatively shallow thus making wind speed especially important here. This paper aims to serve as a preliminary analysis of wind speed and suggests that more in-depth studies on wind speed be conducted. Future studies that more accurately and consistently record wind speed and other data will be useful in further proving this hypothesis. Beach-goers, policy makers, and the South African government can all stand to benefit from studies like this one that examine shark behavior and aim to determine shark critical habitat.