The Science

Hydropower could expand substantially during the twenty-first century in many regions of the world to meet rising or changing energy demands, from socioeconomic development increasing demand for energy to a transition to low-carbon sources of energy. However, this expansion might harm river ecosystems. Wind and solar power, which are types of variable renewable energy (VRE) technology, have the potential to offset hydropower expansion because their cost of production is decreasing, but the nature of this tradeoff is unclear. This study evaluated the relative roles of hydropower and VRE under forces such as declining VRE costs, rapid economic growth, and a transitioning energy system. For the world’s top 20 eco-sensitive river basins, the results show that most basins—including the Amazon, Mekong, and Nile—could experience extensive hydro-deployment under scenarios with rapid economic growth or a transitioning energy system. In the scenarios studied, the results showed that higher levels of deployment of VRE could reduce the expansion of hydropower. Even with more VRE, most regions would still increase their hydropower use.

The Impact

This research contributes a balanced perspective to an active global discussion regarding hydropower’s future role in the world’s most socio-ecologically vulnerable river basins. Until now, discussions have been fragmented, focusing separately on the ecological impacts of hydropower and the role of VRE. This multi-sector dynamic perspective shows that hydropower’s future could be shaped by a complex mix of forces that extend beyond a simple tradeoff between hydropower and VRE. Forces such as socioeconomic growth and a transitioning energy system, as well as regional heterogeneity in hydropower and VRE resource availability and cost, will play critical roles in shaping nuanced regional outcomes. We highlight tradeoffs across metrics, such as meeting energy demands, conserving biodiversity in rivers, and ecosystem services.

Summary

Researchers conducted a multi-sector, global modeling study that found that most of the eco-sensitive river basins across the globe could experience extensive hydropower expansion due to influences including rapid economic growth and a transition to a low-carbon energy system. In the top 20 eco-sensitive basins, scenarios assuming an energy transition led to the highest hydropower growth, with deployment exceeding 80% of potential in over 72% of these basins by 2050, most of which have limited deployment today. Rapid economic growth induced such extensive hydropower deployment in only 44% of eco-sensitive basins. A higher level of deployment of VRE could partially reduce the future expansion, but it is mostly insufficient to completely offset the hydropower expansion seen in the energy transition scenario. This work could inform hydropower development by quantifying the tradeoffs between meeting energy demands and conserving the biodiversity of rivers and ecosystem services. The study was conducted using the Global Change Analysis Model (GCAM), an integrated human systems and energy-water-economy model developed at the Joint Global Change Research Institute of PNNL.

Contact

Marshall Wise, Pacific Northwest National Laboratory, marshall.wise@pnnl.gov

Funding

This research was supported by the Department of Energy, Office of Science, as part of research in MultiSector Dynamics, Earth and Environmental System Modeling Program.