April 2013: The World Bank has released a publication, titled “Greenhouse Gases from Reservoirs Caused by Biochemical Processes: Interim Technical Note,” which aims to update World Bank staff on how to measure GHGs from reservoirs in the context of dam infrastructure projects based on the most recent methodologies.

According to the note, GHG emissions created by a reservoir, including mainly carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O), are the difference between total fluxes for the whole river basin before and after the reservoir is constructed. One of the contributions of the publication is to highlight recent changes in estimates of GHG emissions, which were up to 7% of global GHG emissions a decade ago, and are now considered to represent less than 1%.

The note provides an overview of present methodologies of reservoirs’ GHG measuring, while offering interim recommendations on how to improve the calculus of emissions caused by biochemical processes for planned reservoirs. Some of the recommendations to evaluate the supply of the carbon stock and the reservoir’s condition to create and release GHGs include: questioning its capacity to create large carbon stock –meaning the amount of flooded organic matter produced in the reservoir; understanding the reservoir’s water quality conditions; and evaluating if the reservoir has the capacity to release the created GHGs into the atmosphere.

In concluding, the World Bank advises that the study needs to be updated in the next two years based on current work of the two main groups, the International Hydropower Association (IHA), in collaboration with the International Hydrological Programme (IHP) of the UN Organization for Education, Science and Culture (UNESCO) and the International Energy Agency (IEA) Hydro’s Annex XII. [Publication: Greenhouse Gases from Reservoirs Caused by Biochemical Processes: Interim Technical Note] [UNESCO/IHA Website] [IEA Hydropower Website]