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There are no quick fixes to long-term energy challenges. To find solutions, governments and industry benefit from sharing resources and accelerating results. For this reason the IEA enables independent groups of experts - the Energy Technology Initiatives, or ETIs1.


Researchers retrieving a methane trap from a hydropower reservoir (Wohlen, Switzerland).*

Getting to the bottom of emissions

Policy context
Hydropower represents 17% of total electricity generation worldwide, compared to less than 2% for all other renewable sources combined. Hydropower is a proven technology, and it is reliable and efficient, with low operating and maintenance costs. Pumped storage can help electricity networks balance the variability of integrating other renewable energy sources. There is considerable potential for hydropower, especially in Africa, Asia and Latin America. However, many environmental impact issues must be addressed such as methane emissions from hydropower reservoirs. Due to the high capital investments required for new hydropower projects, policies and measures aimed at providing financial incentives, innovative financing schemes, and market design reforms will alleviate risks for investors and accelerate deployment.

The objectives of the ETI focusing on hydropower (Hydropower) are to encourage awareness, knowledge and support for the sustainable use of water resources for the development and management of hydropower. This includes applying an interdisciplinary approach to hydropower research; increasing knowledge of a broad range of issues relating to hydropower; exploring areas of common interest among international organisations; disseminating balanced, unbiased information on hydropower; and encouraging hydropower deployment. There are eight Contracting Parties, including Brazil and China.

Due to uncertainties and diverging positions regarding GHG emissions from hydropower reservoirs, there is a lack of unbiased information feeding into energy policies, legislations and regulations. Under the project, Hydropower and the Environment: Managing the Carbon Balance in Freshwater Reservoirs, Hydropower members carried out a comprehensive study of the processes connected to reservoir GHG emissions. The goal was to establish best practice guidelines for planning studies on the carbon balance in reservoirs and to standardise GHG evaluation methods. The results of this study are synthesised in the Guidelines for Quantitative Analysis of Net GHG Emissions from Reservoirs. The Guidelines provide a methodology for performing quantitative analysis of net GHG emissions from man-made reservoirs, including advice and recommended procedures for performing in-situ measurements, data analysis and modelling.

The model comprises five stages of measurements: inundation area; reservoir; upstream watershed; reservoir outflow facilities; and downstream reach. General procedures for calculating estimates of net GHG emissions at each stage are outlined, including evaluations of uncertainties.

Advice on planning and executing measurement campaigns and calculating estimates of post-impoundment emissions (uncertainties for existing reservoirs) and pre-impoundment emissions (for both existing and planned reservoirs).

The Guidelines will be useful for hydropower plant operators, local or national GHG trading schemes, environmental impact assessments, and national GHG accounting.

* Photo courtesy of Eawag, Switzerland.



Current projects

  • Hydropower and the environment
  • Hydropower services
  • Hydropower upgrading
  • Renewal and upgrading of hydropower plants
  • Small-scale hydropower

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1.Information or material of the IEA Energy Technology Initiatives, or ETIs (formally organised under the auspices of an Implementing Agreement), including information or material published on this website, does not necessarily represent the views or policies of the IEA Secretariat or of the IEA’s individual Member countries. The IEA does not make any representation or warranty (express or implied) in respect of such information (including as to its completeness, accuracy or non-infringement) and shall not be held liable for any use of, or reliance on, such information.