Operational Impacts and Integration Studies
System Integration researchers at NREL are engaged in the operational impact and integration study areas explained below.
The principal concern of electric utilities unfamiliar with wind energy is that the plant output can suddenly fall to zero. The second-by-second power fluctuations from commercial wind plants are not generally known, although data are becoming available through cooperative efforts between the program and industry. Without long-term data sets from various wind resource regimes, evaluation of the grid impacts of variability cannot be performed. NREL recently expanded its data-gathering effort to include not only Minnesota and Iowa, but also plants in Texas, the Northwest, and California. Over the coming years, locations in Colorado, Wyoming, and other states will be included.
As wind deployment expands into the future, costs for grid integration of wind may increase, especially with higher penetrations. Both short- and longer-term mitigation of intermittency issues, including wind plant forecasting and control, application of energy storage, and regional cooperation could reduce additional integration costs.
Western Wind and Solar Integration Study Update
The Western Wind and Solar Integration Study (WWSIS) is one of the world's largest regional integration studies to date. The fundamental goal of the WWSIS, which is funded by the Department of Energy and coordinated by the National Renewable Energy Laboratory, is to produce a comprehensive dataset that could be used to model the build-out of potential wind plants in the western United States. The Western Wind Resources Dataset will be the basis for assessing the operating impacts and mitigation options due to the variability and uncertainty of wind power on the utility grids. This dataset was designed to help energy professionals perform wind integration studies, compare potential wind sites spatially and temporally, and estimate power production from hypothetical wind plants.
NREL's Systems Integration staff addresses the variable, normally uncontrollable nature of wind power plant output and the additional needs that its operation imposes on the overall grid. At present, the generation and transmission operational impacts that occur due to wind variability are not well quantified. NREL's research will include efforts to quantify and fairly allocate impacts in both an engineering and cost sense. Methods of analysis are at an early stage of development. Without realistic analysis and cost allocation, utilities tend to overestimate imposed operational costs, resulting in the undervaluing of wind power in the system. Unrealistically high ancillary cost evaluations will result in lower wind deployment rates.
While fluctuating power levels and transmission constraints have hampered ready adoption of wind energy to the utility grids, fluctuating water levels, growing pressures on water supplies, the need for flood controls, and environmental issues are just a few of the constraints that may limit the future growth of hydroelectric production. NREL has started a research project to examine whether wind and hydropower technologies can work together to provide a stable supply of electricity to an interconnected grid. While researchers theorize that hydropower facilities may be able to act as a "battery" for wind power by storing water during high-wind periods, a detailed analysis examining regulation, load following, reserve, and generator and grid operations has not been performed.
To gain a better understanding of the synergy that may exist between wind and hydropower technologies, NREL staff is working with federal agencies such as the Bonneville Power Administration, the Western Area Power Administration, and the Tennessee Valley Authority to analyze potential and existing generation projects and watershed basin and electric control areas.
