Estimation of methane emissions from reservoirs for hydroelectric generation in Costa Rica

Greenhouse gas emissions are related to non-renewable sources. For this reason, the methodological guide for the estimation of methane and carbon dioxide emissions in flooded lands was published in 2006 by the Intergovernmental Panel on Climate Change. Since 2016, several studies have been carried out in temperate and tropical zones reservoirs. Costa Rica is a Central American country known for its large hydroelectric resources and its highly renewable electricity generation matrix. This work represents the first study for 11 of 24 hydroelectric plants managed by the Costa Rican Electricity Institute. Methane emissions, energy density and emission factors for electricity generation are determined. Furthermore, a static mathematical model is used to determine these factors with little input data. It is estimated that the greatest contribution to methane emissions corresponds to the Arenal reservoir, which has the largest surface area and the lowest energy density.