Hydropower Systems Integration and Technology Acceptance
Two activities are being supported under Systems Integration and Technology Acceptance:
Hydropower Integration with Other Renewables
Many renewable energy technologies are intermittent in nature, meaning they are not continuously available, because they rely on fuel sources like the wind or sun. Hydroelectric generating plants can "store" energy and then release water to generate electricity when it is needed. This ability to store energy is an asset that can be combined with other renewable technologies like wind energy to enable larger scale use of renewable energy.
With regard to integrating hydropower with other renewable energy, like wind power, hydropower flows are subject to many constraints on operations, including min/max flows and min/max ramp rates. Allowable flows are dictated by multivariate optimization considering the following variables:
- Fish, wildlife, and other related environmental needs
- Irrigation
- Navigation
- Flood control
- Recreation
- Energy/power demands
Often, power needs are not high in priority and energy delivery must fit into constraints imposed by the other system needs.
There are technical, institutional, economic, and political factors that need to be considered. Engineering considerations include integrated controllability and response time of generators, the transmission systems linking the physical locations of the hydropower and wind power facilities, and the characteristics of the utility electric load. In addition, the capacity of the reservoirs, and the seasonal and yearly inflow variability for normal, wet, and dry years can also be important.
Institutional factors hinge mainly on the type of control and responsibility held by a utility or operating agency. For example, a hydropower system may be run in an integrated fashion, where a central utility has responsibility to meet electric load growth. Or, a system may be operated in a more run-of-the river mode, with little seasonal or yearly storage capability, governed more by hydropower capacity, rather than energy (more water available than generators to run it through). Or, a utility may not have load growth responsibility, but will purchase supplementary power for wholesale customers if they request assistance, passing all additional costs directly to those wholesale customers in near real time. Or, power may be allocated on a project-by-project basis (rather than system basis), where there is the ability to store water over long periods, and output is more energy limited than capacity limited (water is short, not limited by the number/size of generators).
Individual institutional situations are important as the context for assessing wind/hydropower integration opportunities. For example, in some cases an individual hydropower resource may be developed for the benefit of specific customers, whereas in other cases, a whole drainage system may be operated in an integrated fashion.
Economic analysis issues are mainly associated with value tradeoffs, market prices, and the ability to limit non-power producing water spills. In addition to the already discussed ancillary service cost issue, differentials in seasonal and daily power demands and prices are important. Peak and off-peak power prices can vary as much as a factor of 3 or 4, resulting in a high value of the ability to shift time of energy delivery.
Politically, hydropower and other water use allocations are often contentious. Some parties may wish to use existing hydropower allocations to support integration of wind energy, where there is interest in wind energy development for economic development reasons. Other entities may see wind energy as a threat to their interests, for example many utilities with federal hydropower allocations also have large investments in fuel production and other electric generating stations, which could potentially be displaced by wind energy generation.
Worldwide, there have been some limited-scope activities aimed at exploring the issues associated with integrated wind-hydropower operations. With results becoming available from an increasing number of pilot studies and investigations, the value of synthesis of best practices is reaching a point where a focused assessment is now appropriate. Lessons-learned from earlier work can now be investigated for appropriateness to future planned projects.
The program will initiate case studies of wind energy-hydropower integration in the United States. The initial studies will identify issues that require further study, and a plan will be developed to address these issues. As they become available, lessons learned will be prepared and reported to stakeholders. The program will also work with international hydropower integration experts and apply international experience to the U.S. market.
The overarching question for studying hydropower integration with wind energy is whether system operating impacts imposed by wind power can be reduced by changing hydropower operations within the constraints imposed on hydropower. In concept, hydropower should be able to provide short- to medium-term buffering of wind plant power fluctuations to reduce ancillary service costs and to increase the economic value of the power delivered. But adding wind power to the system may or may not help hydropower meet power and other system demands by allowing the time of water delivery to be shifted.
The opportunity for hydropower to facilitate large-scale integration of wind energy has long been discussed, but has never been systematically quantified. Specific research objectives are to:
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Determine the technical, economic, and institutional opportunities for and barriers to utilizing the hydro generation facilities to increase the regional amount of wind generation capacity.
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Develop wind production profiles and evaluate the hydropower system requirements for regulation, load following, transmission capacity, and short-term scheduling.
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Quantify the technical and economic costs and benefits of integrating the hydropower and wind power operation.
Outreach Activities
The objective of the program's outreach activities is to establish dialogue among key stakeholders, and catalyze appropriate activities to support the maintenance and development of environmentally, economically, and politically sustainable hydropower markets. The program will pursue establishment of a Hydropower Coordinating Committee whose membership will include representatives from electric utilities and support organizations, state legislatures, state utility commissions, consumer advocacy offices, equipment suppliers and developers, green power marketers, environmental organizations, agriculture and economic development organizations, and state and federal agencies.