Greenhouse gas emissions from hydroelectric reservoirs: Mechanistic understanding of influencing factors and future prospect

Abstract

Abstract Since the pre-industrial era (1990s), greenhouse gas (GHG) emissions from hydroelectric reservoirs have been a debatable subject of interest due to a substantial contribution to global warming. Rising demand for various renewable and non-renewable energy resources became necessary for rapid economic growth to the exponentially rising population in developing countries. Reducing GHG emissions is the key target of COP-26 for climate change mitigation. However, precise methodologies for quantification of GHG, key parameters affecting emission rate is a challenging task attributed to limited tools, techniques for GHG measurement, uncertainty rate in measurement, insufficient GHG database, and huge spatio-temporal variability of emission in global reservoirs. This work highlights the present scenario of GHG emissions from renewable energy with targeted approach on hydroelectric reservoirs, methodological know-how, interrelation between parameters affecting GHG emission, and mitigation strategies. Apart from this, major tools and techniques to predict GHG emissions from hydroelectric reservoirs, accounting of GHG emissions, life cycle assessment, sources of uncertainty, and knowledge gaps have been discussed in detail.