Proceedings of ASME 2010 4th International Conference on Energy Sustainability ES2010 May 17-22, 2010 Phoenix, Arizona, USA DRAFT ES2010-90374 WESTERN WIND AND SOLAR INTEGRATION STUDY HYDROPOWER ANAYSIS: BENEFITS OF HYDROPOWER IN LARGE-SCALE INTEGRATION OF RENEWABLES IN THE WESTERN UNITED STATES Carson M. Pete Thomas L. Acker Northern Arizona University Northern Arizona University Flagstaff, AZ, United States Flagstaff, AZ, United States [email protected] [email protected] Gary Jordan David A. Harpman General Electric Company U.S. Bureau of Reclamation Schenectady, NY, United States Denver, CO, United States [email protected] [email protected] ABSTRACT forecasts and penetration levels, identifying the magnitude and NREL and research partner GE are conducting the Western character of change in generation pattern at each of the selected Wind and Solar Integration Study (WWSIS) in order to provide hydro facilities. Results from this study will focus on the insight into the costs and operational impacts caused by the appropriate benefits that hydropower can provide as a balancing variability and uncertainty of wind, photovoltaic, and resource including adding value to wind and solar and reducing concentrated solar power employed to serve up to 35% of the system operating costs to nearly one billion dollars when load energy in the WestConnect region (Arizona, Colorado, offsetting more expensive generation systems as large Nevada, New Mexico, and Wyoming). The heart of the WWSIS penetration levels of renewable, especially wind power, are is an hourly cost production simulation of the balancing areas in introduced to the grid system. the study footprint using GE’s Multi-Area Production Simulation Model (MAPS). The estimated 2017 load being Key Words: Hydropower, Wind Integration, System Modeling. served is 60 GW, with up to 30 GW of wind power and 4 GW of existing hydropower. Because hydropower generators are INTRODUCTION inherently flexible and often combined with reservoir storage, The North American Electric Reliability Council (NERC) they play an important role in balancing load with generation. develops and enforces reliability standards for entities that are However, these hydropower facilities serve multiple higher engaged in ownership, usage, and operation of the bulk power priority functions that constrain their use for system balancing. system. NERC is a non-profit voluntary organization whose Through a series of comparisons of the MAPS simulations, it goal is to ensure a reliable, adequate and secure electric system. was possible to deduce the value of hydropower as an essential NERC is made up eight regional reliability council members. balancing resource. Several case comparisons were performed These members include: investor-owned utilities, federal power demonstrating the potential benefits of hydro and to ascertain if agencies, independent power producers, power marketers, rural the modeled data was within the defined hydro parameters and electric cooperatives, and state, municipal and provincial constraints. The results, methodologies, and conclusions of utilities. There are a total of 133 control areas within these these comparisons are discussed, including how the hydro regions. Control areas are defined as sub-regions of the system is affected by the wind power for different wind electrical grid that are responsible for meeting the reliability 1 Copyright © 2010 by ASME standards set by NERC and ensuring there is sufficient Environmental Impact Statement and Record of Decision [2]. generation capacity to meet the load demand within the area. A This limits the maximum and minimum generation and flow primary challenge in operating a control area is to ensure there through the turbines along with limiting the up and down ramps is adequate capacity to meet the daily load requirements plus during certain periods. As the price of renewables decline, the additional reliability reserves and to ensure there is adequate feasibility of large-scale wind becomes more practicable. As flexible generation on-line that is able to cover the variation in larger amounts of renewables enter the electrical system, the load that occurs on time scales from nearly instantaneous to integration studies become necessary to determine the hours ahead. The second-to-second fluctuations in load must be operational impacts and costs caused by the variability and met by agile generators outfitted with automatic generation uncertainty inherent in wind and solar. The purpose of this study controls (AGC) and is frequently referred to as regulation. Gas is to examine the impact of hydro power as a balancing resource turbines or hydropower units are capable of meeting regulation in the Western Wind and Solar Integration Study. The objectives requirements. The minute to hour variations are met by quick of this study include investigating the change in hydro response units and is defined as load following. Serving the generation at two of the largest hydro facilities located in the daily load demand requires scheduling units the day before study footprint and to investigate the aggregated hydro use in operation, including both the agile generators that move with the WECC, deducing the value of hydro power using different the load and the base load resources that do not vary several hydro schedules. substantially, such as coal or nuclear powered steam plants. The process of scheduling these units, and the costs incurred due to WESTERN WIND AND SOLAR INTEGRATION STUDY imperfect forecasting is termed unit commitment. The phrase The National Renewable Energy Laboratory (NREL) and “ancillary services” is used to describe the services needed to research partner GE have conducted the Western Wind and meet these day after day fluctuations in load [1]. Solar Integration Study (WWSIS) in order to provide insight As the current trend in generation expansion is to meet into the costs and operational impacts caused by the variability larger and larger amounts of the demand load with clean, and uncertainty of wind, photovoltaic, and concentrated solar reliable and affordable energy sources, renewable energy power employed to serve up to 35% of the load energy in the systems such as wind and solar become increasingly WestConnect region (Arizona, Colorado, Nevada, New Mexico, practicable. On the other hand, these resources are inherently and Wyoming), see Figure 1 for study footprint. Note the study variable dictated by the changing state of the wind and solar footprint is located entirely within the WECC (Western resources. In the case of wind and solar photovoltaics (PV), Electricity Coordinating Council) region, located on the left none of which have intrinsic storage capabilities, electricity side of Figure 1. The WECC represents one of three cannot be efficiently stored on a large scale using currently interconnected electrical systems in the NERC regions, and available technology; it must be used as it is produced. therefore it was necessary to model the entire WECC region in Consequently, when a change in demand or generation occurs, order to correctly model the balancing areas in the WWSIS such as due to the variability in power output from a wind plant, footprint. Using historical load and weather patterns from years somewhere in the interconnected power system the production 2004, 2005, and 2006, the study examined the details of system or consumption of electricity should make a corresponding operation and dispatch though an hourly cost production model change. Thus the variability and lack of storage often results in for each historical year with loads scaled to that expected in the increased costs ensuing from an increased use of ancillary study year of 2017. Because the wind and solar power services to maintain system reliability. One solution to solve the production is directly related to the weather, and because the lack of storage and address renewable energy variability issues load and weather are implicitly correlated, in order to preserve is to couple the system with a clean, responsive generation any correlation that exists between the wind and solar source such as hydropower. Hydropower, as an agile generation production and load, it is important to utilize wind and solar source able to respond to rapid fluctuations in demand, and with power production estimates that are based upon the weather some built-in energy storage in the form of hydro impoundment, patterns that were present in the load years of 2004, 2005 and has long been a valuable resource in electrical system 2006. balancing. Peaking hydro plants like that of Hoover Dam often have a significant water storage capability and are designed to rapidly change output levels in order to satisfy changes in demand for electricity. However, hydro facilities also serve many functions beyond power generation, and these other functions typically are of higher priority such as: water use priorities including irrigation, flood control, navigation, fish habitat, recreation and energy production. These higher priority functions of the dam often limit the true capability of performance of the dam. Such is the case of Glen Canyon Dam where it is operated under the Glen Canyon Dam Final 2 Copyright © 2010 by ASME Gray Mountain, Anderson Canyon, Springerville, Aubrey Cliffs, and Bullhead City (see http://wind.nau.edu/anemometer/ wind_data.shtml for more information about these sites). Figure 2 illustrates an example validation site for January 1, 2006 where an anomalous wind spike is observed in the 100m NREL simulated wind data set (see the large spike displayed by the light blue line at the beginning of Jan. 2). Additionally, 3TIER developed a wind and power production data set for the northern Arizona region for NAU and was used for the selected sites to compare the NREL data set. ANDERSON CANYON W IND DATA 30 30m MET 30m NAU 3TIER 100m NAU 3TIER 100m NREL 25 20 Figure 1: WestConnect Footprint as used in the WWSIS. Source:http://wind.nrel.gov/public/WWIS/MilliganWWSIS 15 SWAT.pdf Wind Speed (m/s) WindSpeed 10 Lack of high quality wind data that is synchronized with the region’s electric load becomes one of the primary obstacles in conducting wind integration studies.