Effects of Climate Change on Hydropower - The SECURE Water Act Section 9505 Assessment

The objective of this project is to evaluate the potential effects of climate change on water availability for federal hydropower generation and on marketing of hydropower by the federal Power Marketing Administrations (PMAs). This assessment is directed by Congress in Section 9505 of the SECURE Water Act (SWA, Public Law 111-11) of 2009, in which the secretary of energy is designated as the lead for this assessment, and it is to be conducted in consultation with the PMAs and other federal and state agencies for every five years until 2023. The second assessment (2013–2016) was led by Oak Ridge National Laboratory (ORNL) and served as the technical basis for a U.S. Department of Energy (DOE) report to Congress that was called for in the SWA. This study also produced near-future water availability projections used in the DOE Water Power Vision study.

This work produces new understanding of future hydroelectric generation from federal facilities, which accounts for approximately half of the installed hydropower capacity in the United States. Surface water is the “fuel” on which hydropower is based, and that resource can be directly affected by climate change, as well as by other competing water uses. Understanding the potential effects of climate change on water availability for hydropower generation is of great importance to the US renewable energy portfolio and the reliability of the electricity grid. To evaluate the climate change effects on 132 federal hydropower plants across the entire United States, a spatially consistent assessment approach is designed to enable an interregional comparison. This assessment uses a series of state-of-the-art models and methods with different spatial resolutions to hierarchically downscale the global climate change signals into watershed-scale hydrologic projections to support the evaluation of future annual and seasonal hydropower generation. A variety of historic meteorological and hydrologic observations, hydropower facility characteristics, and geospatial datasets is integrated to support model development, calibration, and verification.

This assessment is featured by extensive consultation with the PMAs, as well as with other agencies including federal hydropower owners (US Army Corps of Engineers [USACE] and the U.S. Department of Interior [DOI] Bureau of Reclamation [Reclamation] under the DOE-DOI-USACE Memorandum of Understanding for Hydropower). This assessment also benefited from technical collaboration with the federal Climate Change and Water Working Group CCAWWG. In addition to evaluating effects and risks from climate change, the assessment addresses potential changes in operation or contracting practices that may mitigate adverse impacts. Potential adaption strategies are also suggested in this study. This study promotes better understanding of the sensitivity of federal power plants to water availability and provides a basis for planning future actions that will enable adaptation to climate variability and change. The end users of information include congressional members and their staff, the PMAs and their customers, federal hydropower owners/operators, hydropower developers, environmental stakeholders, and the DOE Water Power Technologies Office.