Climate impact of tropical hydropower: a perspective on G-Res model calculations

Abstract

Despite environmental and social issues, hydropower has been promoted as a climate-friendly form of electricity generation. This perspectives paper shows that such a claim needs to be considered with great care, especially in tropical, low-latitude areas. First, because complete climate impacts are rarely considered. For instance, IPCC emission intensities omit biogenic CO2 emissions from reservoirs. The openly available G-Res tool provides an opportunity to partly fill this gap, but it fails to consider several significant effects. Second, individual cases show huge variability in climate impacts. In this paper, we discuss the results of G-Res calculations for three projects in Myanmar, which confirm this large variability. An analysis of the methodology shows that the G-Res calculations can substantially underestimate the climate impacts of hydropower projects due to its limitations and assumptions. Furthermore, the Earth’s albedo change by the reservoirs needs to be considered. We show that the impact thereof is of comparable magnitude and variability. As a result, in many cases in the tropics hydropower will have considerably larger climate impacts than solar and wind and can even exceed those of fossil fuel installations.