Greenhouse gas emissions
Hydropower is a low-carbon technology which helps to offset the carbon emissions of fossil fuels.
In certain conditions, a reservoir created by a hydropower dam will release greenhouse gases due to the decomposition of flooded organic material. In other conditions, a reservoir may act as carbon sink: absorbing more emissions than it emits.
A number of researchers have measured reservoir emissions at dam sites around the world, but each study is usually site-specific and the results not applicable to the great majority of reservoirs elsewhere.
Since 2006, IHA has been working with UNESCO, the World Bank and a range of stakeholders to develop common understanding to assess the carbon profile of hydropower facilities and reservoirs.
This work resulted in the publication of the UNESCO/IHA GHG Measurement Guidelines for Freshwater Reservoirs.
In 2017, in collaboration with the UNESCO Chair for Global Environmental Change, IHA launched a publicly available online tool that allows hydropower companies, investors, consultants, decision-makers and other stakeholders to more accurately report on the net impact on greenhouse gas (GHG) emissions.
The G-res tool uses a new modelling methodology based on current scientific knowledge and over 500 empirical measurements from more than 200 reservoirs worldwide.
Using readily available input data, it provides a way to assess GHG impacts without the need for large-scale field measurement campaigns and multi-year studies.
The G-res tool builds upon a new conceptual framework developed in cooperation with researchers from the University of Quebec at Montreal (UQÀM), the Norwegian Foundation for Scientific and Industrial Research (SINTEF) and the Natural Resources Institute of Finland (LUKE). Find out more.