Greenhouse gas emissions of hydropower in the Mekong River Basin can exceed those of fossil fuel energy sources
Hydropower is commonly considered as a clean energy source to fuel Southeast Asian economic growth. Recent study published in Environmental Research Letters finds that hydropower in the Mekong River Basin, largest river in Southeast Asia, might not always be climate friendly. The median greenhouse gas (GHG) emission of hydropower was estimated to be 26 kg CO2e/MWh over 100-year lifetime, which is within the range of other renewable energy sources (380 kg CO2e/MWh). The study concludes that hydropower in the Mekong cannot be considered categorically as a clean energy source; instead, the emissions should be evaluated case-by-case together with other social and environmental impacts.
Mekong River is a global hot spot for hydropower development. The economy in the region is growing rapidly and hydropower is broadly seen as a viable source for satisfying growing energy demands. However, the extensiveness of hydropower development has raised concerns on ecological and social sustainability, particularly in the case of rich inland fisheries of which millions depend for livelihoods and food. Less attention is put, however, on the potential climate impacts of the hydropower although case studies from other tropical regions show that hydropower emissions cannot be neglected. The emissions originate mainly from degradation of organic material in the reservoir but also from dam construction.
In the Mekong Basin emission measurements exist only from a few reservoirs, and the study led by Aalto University, Finland, is the first one to estimate the emissions of the entire hydropower development in the basin. The study estimated emissions of 64 existing and 77 planned hydropower reservoirs using statistical models that are based on global emission measurements. The focus was on gross emissions of CO2 and CH4 through the reservoirs water surface. The results are reported as CO2 equivalents (CO2e) that combines the CO2 and CH4 emissions.
— source alphagalileo.org