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HomeMy WebLinkAboutSaint George Preliminary Wind Feasibility Study - Dec 2004 Preliminary Wind Energy Report: St. George, Alaska Prepared for Alaska Energy Authority (AEA) and St. George Chadux Corporation Prepared by Mia Devine National Renewable Energy Laboratory (this is not an official document of NREL) December 13, 2004 Preliminary Wind Energy Report for St. George, Alaska Page 2 of 8 Introduction The purpose of this report is to provide a preliminary analysis of the wind energy options in St. George. A wind power system in Alaska can range in size from a small wind turbine providing electricity to a single building (such as the 10kW Bergey wind turbine connected to the community building in Port Heiden) to a wind farm connected to an electric grid serving a large urban area (such as that proposed for Fire Island). This report focuses on village-scale systems where the wind turbines are integrated into the traditional diesel power plant and grid system serving the community. The primary pieces of information required to consider the feasibility of a wind-diesel power project are: 1) The wind resource – the greater the wind speed the more electricity that can be produced from each wind turbine and the greater the potential fuel savings. The turbulence and variability of the wind also has an effect on the performance of a wind turbine. 2) Energy use in the community – the amount of electricity that is needed as well as the patterns of usage, affects the ability of the system to absorb all of the wind-generated electricity. The wind turbines may also be able to provide energy to heating loads. 3) Estimated Costs – the cost of different technology options and the expected diesel fuel price will have a large impact on the viability of wind projects. The costs included in this report are based on best estimates for rural Alaska but are not assessed for the specific location of St George. The final project cost will be influenced by the availability of large cranes and pile drivers in the community, the local soil conditions, and the availability of local labor. This report will summarize the wind resource and electric load data that is available to date. A preliminary estimate of the power production and costs associated with the installation of a wind energy system are also provided as a rough analysis of the potential opportunities in St. George. Wind Resource in St. George Wind resource data was obtained from the St. George airport weather station. Figure 1 shows the average monthly wind speeds based on 5 years of data measured at a 10-meter height. Preliminary Wind Energy Report for St. George, Alaska Page 3 of 8 0 1 2 3 4 5 6 7 8 9 10 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov DecWind Speed (m/s)0.0 2.2 4.5 6.7 8.9 11.2 13.4 15.7 17.9 20.1 22.4 Wind Speed (mph) Figure 1. Average Monthly Wind Speeds in St. George (10-meter height) As shown, the wind speed is much greater during the winter months than the summer months, with an annual average of 16.8 mph (7.5 m/s). Typically, wind speeds increase with height above the ground. It is estimated that the annual average wind speed at a typical wind turbine hub height of 30 meters will be 19.5 mph (8.7 m/s). Figure 2 shows how the average hourly wind speed changes throughout the day. During a typical January day the wind speed tends to remain steady, while during a typical July day, the wind speed increases slightly to a peak in the afternoon and then dies down in the evening. Figure 2. Diurnal Wind Speed Profiles in St. George (10-meter height) St. George Island is in close proximity to St. Paul Island, which has been successfully operating a wind power plant since 1999. It is believed that the two islands will have a similar wind resource. Long-term data from the St. Paul airport indicate an annual average wind speed of 15.4 mph versus 16.7 mph at the St. George airport, although this difference may have more to do with the specific location of the airport anemometers rather than the prevailing winds. Preliminary Wind Energy Report for St. George, Alaska Page 4 of 8 Current and Expected Energy Requirements in St. George The diesel power plant in St. George consists of three diesel generators with a total capacity of 675 kW (individual ratings: 150, 175, and 350 kW). According to PCE records, the electric load in St. George has been decreasing at an average rate of 3% per year since 1996, primarily due to a decrease in population. With increasing interest in the tourism industry and the expected improvements to the airport, harbor, school, and public water system, it is expected that the electric demand in St. George will begin to increase. The estimated electric demand in the year 2015 was calculated by adding the estimated electric consumption of each new facility to the base 2003 electric load (Devine, 2004). The resulting electric demand is summarized in Table 1 and Figure 4. Table 1. Electric Use in St. George Year 2003 2015 Average Load 98 140 Peak Load 225 250 kWh/year 855,200 1,224,000 Figure 3. Electric Demand in St. George Estimated Performance of Wind-Diesel Systems in St. George Three wind turbine manufacturers have expressed an interest in the Alaska market by their participation as a vendor at the Wind-Diesel 2004 conference held in Girdwood, Alaska: 1) Entegrity (formerly Atlantic Orient Corp) – the EW15 (AOC15/50) wind turbine is rated at 66 kW and is assembled in Prince Edward Island Canada. www.aocwind.com 2) Northern Power Systems – the Northwind100/19 wind turbine is rated at 100 kW and is assembled in Vermont. www.northernpower.com 3) Fuhrlander – the FL100 and FL250 wind turbines are rated at 100 kW and 250 kW, respectively. They are designed and manufactured in Germany and supplied though Lorax Energy Systems located in Rhode Island. www.lorax-energy.com Preliminary Wind Energy Report for St. George, Alaska Page 5 of 8 The expected energy production from each of these wind turbines was calculated by comparing the hourly wind resource at St. George to the power performance curves for each wind turbine. Results are shown in Table 2. Table 2. Expected Energy Production from Different Wind Turbines in St. George Turbine Model Entegrity 15/50 Northern Power Northwind100 Fuhrlander FL100 Fuhrlander FL250 Rated Capacity 66 kW 100 kW 100 kW 250 kW Gross kWh Produced per year 1,219,900 1,237,400 kWh 1,267,900 kWh 1,673,200 kWh Capacity Factor 42% 45% 45% 41% The ability of the various wind turbines to meet the village demand is characterized by the wind penetration level. Wind penetration is calculated as the average electricity (kWh) produced by the wind turbines divided by the total electricity (kWh) required by the village. Different penetration levels require different balance of system equipment to allow for proper communication between the wind turbines and diesel generators. Also, different costs are associated with each penetration level. Low-penetration systems, where the wind turbines provide up to 20% of the annual village load, are the most simple and require the least amount of initial investment for balance of system equipment. Medium-penetration systems (between 20 and 50% of the annual village load) require additional controls, while high-penetration systems (over 50% of the village load) require specialized equipment that will allow the diesels to be shut off for extended amounts of time. At least one diesel is always operating in low and medium penetration systems. A software based simulation tool is employed to conduct an initial level of analysis (HOMER, 2004). The HOMER software package, developed by the National Renewable Energy Laboratory, uses the hourly electric loads, hourly wind resource, and the wind turbine and diesel generator specifications to estimate power production and fuel requirements for various system configurations. In this analysis we have used the estimated electric load for 2015 discussed above, but all of the cost information is based on an installation in 2004/5. In calculating the simple payback, the average diesel fuel price in St. George from FY2004 was used. This analysis has not taken into account the replacement of the existing diesel power station but assumes that it is being operated using automated controls. Any savings associated with the reduced diesel fuel storage requirements or the potential value of using excess wind electricity for heat has not been assessed in this analysis. Table 3 summarizes the estimated performance and costs associated with the installation of various numbers and types of wind turbines, listed in order of increasing installed cost. The Preliminary Wind Energy Report for St. George, Alaska Page 6 of 8 estimated costs include the installed cost of the wind turbines and the required balance of system components for each penetration level, based on previous project experience. Table 3. Estimated Performance of Wind-Diesel Hybrid Power Options in St. George # and type of wind turbine AOC 15/50 NW 100 FL 100 FL 250 Estimated Installed Cost Average Wind Penetration Estimated Diesel Fuel Use (gal/yr) Estimated Diesel Fuel Savings1 (gal/yr) Excess Wind Electricity (kWh/yr) Simple Payback2 (years) Diesel-only System - - 86,700 - 0 - 1 $295,000 20% 71,700 15,000 800 9 1 $495,000 33% 62,800 23,900 19,100 9 1 $502,000 41% 58,200 28,500 49,200 8 2 $530,000 39% 59,400 27,400 51,300 9 3 $860,000 59% 53,700 33,000 167,200 11 1 $947,000 88% 47,200 39,500 345,900 9 2 $985,000 65% 52,200 34,600 198,900 11 2 $999,000 82% 48,800 38,000 303,400 10 4 $1,055,000 79% 50,400 36,300 300,200 11 5 $1,250,000 99% 46,400 40,400 471,400 11 3 $1,361,000 123% 39,500 47,200 675,400 11 3 $1,400,000 97% 46,100 40,700 443,900 13 2 $1,619,000 176% 29,600 57,200 1,230,000 12 1. Fuel savings depend on the ability of the system to absorb the wind-generated electricity. That ability depends on the electric demand of the village and the diesel control strategy. The estimated 2015 electric demand and a conservative control strategy requiring an operating reserve equivalent to 10% of the village load and 15% of the wind power output were used in this analysis. 2. Payback is calculated simply as the total installed cost divided by the annual cost savings from reduced fuel consumption, based on a constant diesel fuel price of $2.22/gallon. It does not include the O&M costs of wind turbines or diesel generators, fuel storage costs, or other economic factors. Because detailed site and installation capabilities are unknown, a specific recommendation is not provided as part of this analysis; however, a number of options are listed in Table 3 so the reader can select the one that best fits their needs. Next Steps for Pursuing Wind Energy Options in St. George This preliminary analysis indicates that wind energy is a viable option in St. George and warrants further study. Based on conservative estimates, a number of wind/diesel system options result in a simple payback period of 10 years or less. A more detailed analysis should be conducted as the next step in the decision process. If this indicates that the project is viable, an engineering design is required before equipment is purchased or installed. The next steps in pursuing wind energy options in St. George include: 1) Data collection a. A meteorological tower and wind monitoring equipment was installed at the proposed wind turbine location in September 2004. This wind data should be Preliminary Wind Energy Report for St. George, Alaska Page 7 of 8 correlated to an existing monitoring site with a reasonable recording record, in this case the St. George Airport. It will be important to collect wind data from the airport that is concurrent to the measurement at the site. b. Measure the current plant performance including hourly or 15-minute recordings of plant power, frequency, and voltage. This can be done through manual recordings by the plant operator or the installation of a power monitor. c. Assess the status of the current power system generators, including measurement of fuel consumption rates. d. Analyze existing and planned power usage including efficiency measures and expected community power needs. e. Quantify the heating requirements in the village to identify possible uses for excess wind electricity. 2) Perform an initial geotechnical study to determine the soil conditions and type of wind turbine foundation that would be required. 3) Initial environmental impact assessment – the following issues should at least be addressed at a preliminary level, each of which may be studied in greater detail in subsequent phases of the project: a. impact on flora and fauna (including migrating birds with a focus on any endangered or protected species) b. impact on areas of archaeological or historical significance 4) Social acceptance study to determine the acceptance of the wind projects with local residents. Although this analysis will be conducted for the whole community, special focus should be given to buildings or dwellings close to the proposed turbine sites. This study should include an assessment of the following items in concert with public meetings: a. visual impact of the wind turbines b. noise impacts c. affect on ambient air quality 5) Completion of a feasibility study based on data collected from the site to determine the specific project costs and potential savings. Various power system options should be evaluated and the following performance characteristics should be addressed: a. Uses of any excess power generated by a hybrid power system b. Comparison of the hours of operation of the diesel generators and wind turbines based on different system configurations c. The fuel consumption and installed costs of the different system options d. Loss of load expectation/ probability of different system configurations e. Potential interference with telecommunications systems and aircraft Preliminary Wind Energy Report for St. George, Alaska Page 8 of 8 f. Lifecycle cost analysis of the different system options 6) Detailed System Analysis and Design – If the decision is made to move ahead with the project, a detailed design of the selected system will have to be completed which will include drawings and specifications of all power system components and the control system. Additional Information A number of Excel spreadsheets were developed in the process of creating this report, which includes the following information: 1. Historical and expected electric load growth in St. George 2. Long-term wind speed data from St. George airport 3. Community survey form These spreadsheets are available upon request from the Alaska Energy Authority or the National Renewable Energy Laboratory. References Clausen, Niels-Erik, et al. “Isolated Systems with Wind Power: An Implementation Guideline.” Riso National Laboratory, Roskilde, Denmark. Riso-R-1257(EN). June 2001. Devine, Mia. “The Alaska Village Electric Load Calculator.” National Renewable Energy Laboratory. TP-500-36824. September 2004. http://www.nrel.gov/publications HOMER, The Optimization Model for Distributed Power. Website accessed November 29, 2004. http://www.nrel.gov/homer Alaska Rural Energy Conference 2004 Proceedings. Talkeetna, Alaska. April 2004. http://www.uaf.edu/aetdl/conferences.htm Wind Diesel 2004 Conference Proceedings. Anchorage/Girdwood, Alaska. September 2004. http://www.eere.energy.gov/windandhydro/windpoweringamerica/wind_diesel.asp Acknowledgements This report was conducted based on the support of the Windpowering America Program sponsored by the U.S Department of Energy through the National Renewable Energy Laboratory’s National Wind Technology Center in Boulder, Colorado under the guidance of Larry Flowers and Ian Baring-Gould. Further support was also provided by the Alaska Energy Authority. Disclaimer This report represents an initial analysis of the options associated with modifying the existing diesel-based power system for the community of St. George using wind energy. By their nature the development of such wind/diesel power systems is complex and multi-faceted. Although a genuine effort has been made by the author to accurately assess the impact of the possible options, the conclusions of this report are based on basic information and should be assessed based on this understanding.