A new approach to assessing the water footprint of hydroelectric power based on allocation of water footprints among reservoir ecosystem services

Hydroelectric power is an important energy source to meet the growing demand for energy, and large amounts of water are consumed to generate this energy. Previous studies often assumed that the water footprint of hydroelectric power equaled the reservoir’s water footprint, but failed to allocate the reservoir water footprint among the many beneficiaries; dealing with this allocation remains a challenge. In this study, we developed a new approach to quantify the water footprint of hydroelectric power (WF_h) by separating it from the reservoir water footprint (WF) using an allocation coefficient (η_h) based on the ratio of the benefits from hydroelectric power to the total ecosystem service benefits. We used this approach in a case study of the Three Gorges Reservoir, the world’s largest reservoir, which provides multiple ecosystem services. We found large differences between the WF_h and the water footprint of per unit of hydroelectric production (PWF_h) calculated using η_h and those calculated without this factor. From 2003 to 2012, η_h decreased sharply (from 0.76 in 2005 to 0.41 in 2012), which was due to the fact that large increases in the value of non-energy ecosystem services, and particularly flood control. In 2009, flood control replaced hydroelectricity as the largest ecosystem service of water from the Three Gorges Reservoir. Using our approach, WF_h and PWF_h averaged 331.0 × 10⁶ m³ and 1.5 m³ GJ⁻¹, respectively. However, these values would almost double without allocating water footprints among different reservoir ecosystem services. Thus, previous studies have overestimated the WF_h and PWF_h of reservoirs, especially for reservoirs that serve multiple purposes. Thus, the allocation coefficient should not be ignored when calculating the WF of a product or service.     

Baselines of acceptability and generational change on the Mactaquac hydroelectric dam headpond (New Brunswick,Canada)

Hydroelectricity is an old yet reliable form of renewable energy, with acknowledged social and ecological impacts. A tension currently exists between such concerns and energy needs, with dam construction and removal ongoing around the world. It is critical to better understand the implications of both on local citizens. We performed map elicitation interviews with 20 locals around the prematurely-aging Mactaquac Dam and headpond, in New Brunswick, Canada, to understand if and how they came to accept the dam landscape, and what they want for its future. A Baselines of Acceptability conceptual framework was developed to guide the interpretation. Respondents demonstrated attachment to the dam-in-place landscape, even those initially disadvantaged by its construction, and a preference for keeping the headpond intact. Despite this demonstrated adaptability, the paper calls for improved transparency, scope and justice in energy landscape decision-making, as well as further testing of the framework with different demographics, infrastructure case studies and over time.     

Climate change may impair electricity generation and economic viability of future Amazon hydropower

Numerous hydropower facilities are under construction or planned in tropical and subtropical rivers worldwide. While dams are typically designed considering historic river discharge regimes, climate change is likely to induce large-scale alterations in river hydrology. Here we analyze how future climate change will affect river hydrology, electricity generation, and economic viability of > 350 potential hydropower dams across the Amazon, Earth’s largest river basin and a global hotspot for future hydropower development. Midcentury projections for the RCP 4.5 and 8.5 climate change scenarios show basin-wide reductions of river discharge (means, 13 and 16%, respectively) and hydropower generation (19 and 27%). Declines are sharper for dams in Brazil, which harbors 60% of the proposed projects. Climate change will cause more frequent low-discharge interruption of hydropower generation and less frequent full-capacity operation. Consequently, the minimum electricity sale price for projects to break even more than doubles at many proposed dams, rendering much of future Amazon hydropower less competitive than increasingly lower cost renewable sources such as wind and solar. Climate-smart power systems will be fundamental to support environmentally and financially sustainable energy development in hydropower-dependent regions.