In the last issue of Our Water Matters, we kicked off an exploration of the complex interplay between water and energy based on the example of hydropower, the harvesting of electricity from the power of falling water.
The Department of Energy’s Oak Ridge National Laboratory (ORNL) maintains a Water Power Program within its Energy Science and Technology Directorate whose mission is to “enhance and accelerate the contributions of water power in facilitating more reliable, resilient, and affordable electric power sources, infrastructure, and systems.” ORNL describes hydropower as “a key contributor to the nation’s energy portfolio, helping to fill in the gaps between traditional sources of electricity and intermittent sources such as wind and solar.”
In order “to better understand and predict the conditions that impact sustainable hydropower electricity generation,” ORNL launched the Section 9505 Assessment to design a “spatially consistent assessment approach … to gradually downscale global environmental change signals into watershed-scale hydrologic projections.” Among the most critical issues threatening the resilience of hydropower systems and infrastructure, the assessment’s authors identify “the duration and severity of extreme drought events” which are “projected to increase in many parts of the United States” as well as the “timing of available supply and peak demand [which] is increasingly coming into conflict.”
According to the ORNL’s energy demand analysis, “temperature-driven water and energy demand is expected to shift from winter to summer,” presumably due to rising temperatures that will result in hotter winters and summers. “Although, ideally, one may expect to mitigate this conflict through reservoir management, the intensified hydrologic extremes combined with all other competing water management objectives will limit the ability and flexibility to store more water resources to meet peak demand,” write the assessment’s authors. “Furthermore, in arid regions, the enhanced reservoir evaporation [due to higher ambient temperatures] may result in a sizable reduction in storage and further exacerbate the nexus of electricity demand and water availability … Overall, the results suggest that maintaining operational flexibility remains a key challenge for federal hydropower reservoirs.”
Any approach to managing these reservoirs must take into account the critical role watersheds play not only in energy generation but also “in supporting … drinking water supplies, agriculture, and recreation.” According to ORNL, “Rising demand for these essential services, coupled with environmental changes, is placing unprecedented stress on water resources. In turn the strain on the system is increasing uncertainty and competition for these resources, impacting everything from reservoir operations to river-basin management.”
In order to grapple with these challenges, ORNL has developed a “Roadmap to Intelligent Watersheds” that integrates “advancements in monitoring, data sharing, supercomputing, modeling, and artificial intelligence … to connect data more effectively with decision-making, particularly at the complex watershed scale.”
Another resource that ORNL has developed is HydroSource, “a comprehensive national water energy digital platform” to promote “a better understanding of the sensitivity of power plants to water availability” and provide “a basis for planning future actions that will enable adaptation to environmental variability and change.” HydroSource includes the “new stream-reach development data set” that “identifies untapped U.S. stream-reaches with high (greater than 1 MW) and low (less than 1 MW) energy potential.” The data set comprises “more than 100 reaches” where hydroelectricity dams could be constructed “with at least 100 MW of potential capacity.”
However, as author and UT-Austin professor Michael E. Webber writes in his book titled “Thirst for Power: Energy, Water, and Human Survival,” the “construction of large dams has such a large impact on ecosystems” that it makes “building new ones … contentious in most developed countries. While efforts to build major dams are still under way in Asia and South America, increasing hydropower generation in the United States and Europe faces a lot more resistance.”
As a result, grid managers in this country might have better luck pursuing “smaller-scale opportunities, known as ‘small hydro’ or ‘microhydropower.’” Webber goes on to point out that ORNL has identified “new power generating capacity … by adding power houses to some of the 80,000 dams in the United States that are used for storing water, controlling floods, and managing navigable waterways, but do not make electricity.” Also known as “new stream-reach development (NSD) opportunities,” these projects “form an overwhelming majority of the nation’s remaining hydropower resource potential,” according to ORNL. Webber contends that “[b]ecause these nonpowered dams have already incurred many of the construction costs and ecosystem impacts, adding power to the existing dam site is often a faster, less expensive, and less controversial way to expand hydropower than creating new reservoirs that displace people and flood ecosystems.”
From assessments to roadmaps to new stream-reach development opportunities, the United States will need all of the above and more to meet the challenges posed by our new climate reality. But hydroelectricity is just one of the many sources of power dependent on an abundant supply of water. As we continue taking a closer look at the water energy nexus, the next issues of Our Water Matters will delve into other forms of energy that all share the same indispensable ingredient.
Trey Gerfers serves as general manager of the Presidio County Underground Water Conservation District. A San Antonio native, he has lived in Marfa since 2013 and can be reached at tgerfers@pcuwcd.org.
