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Project Background
Northwest Sustainable Energy for Economic Development (NWSEED) launched the Northwest Wind Mapping Project in mid 2001 in partnership with the Last Mile Electric Cooperative, a group of rural public utilities working to develop cost-based wind generation. Taking a leap of faith, the Northwest Cooperative Development Center agreed to be fiscal host for the mapping project when just partial funding was committed. Fortunately, numerous public agencies, utilities, private wind developers and turbine manufacturers, consulting firms, and other non-profit organizations came on board to co-sponsor the effort.
The wind atlas previously available for the region was based on old data and methods which under-estimated and overstated resources for specific locations. The computer techniques used to develop the new maps will provide important data for daily and seasonal wind patterns, which can be compared to other resources and loads to identify the most valuable areas. Through CDROM data and a zoom-in web interface, the maps will greatly aid rural communities in exploring opportunities to harness wind energy.
Overlays adding extra value will include transmission and distribution systems, sensitive wilderness and cultural areas, and utility service territories. Although the maps will not eliminate the need for on-site wind resource measurement for large-scale installations, they will help utilities and developers screen out less promising areas, significantly minimizing the cost and timing of prospecting. They will also help landowners make a first-cut determination of the feasibility of installing distributed wind turbines to supply power on-site.
The maps will be widely disseminated as glossy color posters to all libraries, utilities, county commissions, community action agencies and extension offices throughout the 6-state region as well as via e-mail and hotlinks on numerous high-traffic web sites.
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Background
One of the most crucial pieces of information needed when evaluating the wind energy potential of any given area or site is a reliable definition of the wind resource. General knowledge about the Northwest's wind energy resources is based either on a limited number of site-specific wind measurement programs or on a coarse, outdated national atlas produced by the federal government in the mid-1980's. These programs have resulted in only limited insights into the complex distribution of wind resources throughout the region. Consequently, government planners, energy service companies, private developers, businesses and homeowners have little quantitative information from which to make informed wind energy siting and planning decisions unless they first invest in additional time-consuming and expensive wind measurement programs.
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Objective
The objective of this mapping initiative is to define and map the wind resource characteristics of the Northwestern U.S. including its offshore areas, to support the planning and evaluation of future wind energy development opportunities. A key product of this effort will be seasonal maps of the wind resource in order to provide the information necessary to assess the feasibility of using wind energy for irrigation applications. A GIS-based site screening effort will also be employed to identify and rank the most promising potential wind development areas. Overlays will include roads, transmission lines, boundaries of sensitive wilderness areas, National Parks and Indian reservations, and urban areas.
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Benefits
High resolution wind resource maps and the associated information products will benefit a broad cross-section of users - government planners, energy service companies, private developers, businesses and homeowners. These products will enable users to make informed decisions by giving them direct access to the latest and most comprehensive information available on the wind resource. At the local level, these products will help users decide, for example, whether wind energy development is feasible and if an investment in a site-specific study is warranted. On a larger scale, the products will help answer such questions as: how much development potential is there, where are the best areas, what are the economic development opportunities, what are the most obvious barriers and sensitivities, at what cost can electricity be generated, and so on. States and energy companies can adapt these maps to their specific energy programs. In short, this wind mapping initiative is designed to facilitate future wind energy planning and siting decisions - as well as technology transfer activities - by utilizing state-of-the-art modeling techniques to improve access to the most important planning parameters.
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Approach
TrueWind Solutions employed its advanced MesoMap™ mesoscale modeling system to produce the wind resource maps of the Northwestern U.S. MesoMap was developed to simulate complex meteorological phenomena not adequately represented in standard wind flow models. It is therefore capable of modeling sea breezes, offshore winds, mountain/valley winds, low-level nighttime jets, temperature inversions, surface roughness effects, flow separations in steep terrain, and channeling through mountain passes, which are of importance in the Northwest. This model utilizes historical upper air and surface meteorological data, thereby providing a consistent long-term, 3-dimensional wind resource record. This record can later be used as a substitute for long-term surface wind measurements in the correlate-measure-predict (CMP) method, which adjusts short-term site measurements to the long-term climatological norm. The results of this model provide more precision to the GIS site identification task by supplying a highly-resolved spatial definition of the wind resource and of the relative performance of wind turbines at potential development sites. This in turn provides much greater certainty about site specific wind conditions, wind plant performance, and project economics without the need for a widespread wind measurement program. Indeed, the modeling results can help identify where limited wind measurement resources should be applied.
The MesoMap system was used to simulate the wind speed and direction over the region on a 400 meter grid at multiple heights (30-, 50- and 70-m) above ground level. Meteorological input data was randomly sampled from a historical database (known as reanalysis data, which were compiled by the National Centers for Environmental Prediction and National Center for Atmospheric Research) to establish the boundary conditions at the top and sides of the model domain, while all significant processes that determine winds near the surface were calculated internally by the model. The results of the simulations were then collected and processed into wind roses, speed frequency distributions, and color-coded maps of mean wind speed. Maps of wind turbine production for one or more selected turbine power curves will also be produced to provide a truer indication of site attractiveness.
To validate the wind resource maps, TrueWind generated long-term mean wind speed estimates for locations where there are reliable and representative measurements on high-elevation terrain. The National Renewable Energy Laboratory and additional independent meteorologists compared the predicted speeds with measured speeds (adjusted to the long-term norm) extrapolated to a standard hub height (50 m). TrueWind is working to generate error statistics (mean bias, standard deviation) and, where necessary, analyze and correct for sources of error. Based on prior model validations, the expected range of discrepancy between measured and predicted winds in complex terrain is 3 to 7%.
The final deliverables will be 1) a digital copy on CDROM of the gridded wind resource data for the region, and 2) a report containing the color-coded wind maps, site list, selected wind roses and frequency distributions, comparison with measurements, and a description of the methodology.
Presentation on True Wind MesoMap Wind Mapping System
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About TrueWind Solutions
TrueWind Solutions, LLC is a wholly owned partnership of three firms: AWS Scientific, Inc., Brower & Company, Inc., and MESO, Inc. Established in 1998, the firm specializes in the development and application of advanced mesoscale atmospheric models to wind resource assessment and wind forecasting. The partners bring a complementary set of skills and experience that together make TrueWind one of the world's leading wind energy services companies. Current and past clients include BC Hydro, the New York State Energy Research and Development Authority, National Renewable Energy Laboratory, Tennessee Valley Authority, the World Bank, the Quebec Ministry of Natural Resources, Southern California Edison, and the Electric Power Research Institute. Since its introduction three years ago, the MesoMap wind mapping system has been applied in 15 countries on four continents. In North America alone wind maps have been or are being produced in three provinces and 22 states.
The key TrueWind staff involved in the wind mapping task are Dr. Bruce Bailey and Dr. Michael Brower. Dr. Bailey has 25 years experience in wind energy research and consulting, primarily in the areas of resource assessment, wind plant siting & design, and project management. Dr. Brower has a broad background in energy policy analysis, windflow modeling, and GIS database applications.
TrueWind Solutions, LLC 251 Fuller Road
Albany, New York 12203
518-437-8661, 518-437-8659 fax
www.truewind.com
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