Balancing renewable energy and river resources by moving from individual assessments of hydropower projects to energy system planning

As governments and non-state actors strive to minimize global warming, a primary strategy is the decarbonization of power systems which will require massive increase in renewable electricity generation. Leading energy agencies forecast doubling hydropower capacity as part that necessary expansion renewables. While provides generally low-carbon generation can integrate variable renewables, such wind solar, into electrical grids, dams are one reasons only one-third world’s major rivers remain free-flowing. This loss free-flowing has contributed dramatic declines migratory fish sediment delivery agriculturally productive deltas. Further, reservoirs behind have displaced tens millions people. Thus, challenges efforts meet climate targets while simultaneously achieving other Sustainable Development Goals. In this paper, we explore strategies achieve needed sustaining diverse social environmental benefits rivers. These be implemented at scales ranging from individual project (environmental flows, passage site-level mitigation) cascades river basins regional systems. review evidence project-level management mitigation reduce costs, posit most effective scale for finding balanced solutions occurs We further hypothesize pursuit system also provide investors, developers governments; these broad uptake approaches described paper. test hypothesis through cases Chile Uganda demonstrate potential system-scale planning allow countries with avoid damming high priority (e.g., those would cause conflicts benefits) similar cost status quo approaches. show that, reduction risk conflict, strategic site selection improve financial performance investors developers, case study Colombia.