Greenhouse Gas Emissions from Reservoirs
The study clearly indicates that carbon dioxide and methane diffusion decrease within the first 20 or more years of a new reservoir being created; however, methane emissions through ebullition and degassing persist and can increase over time. Measurements made at hydroelectric facilities in boreal and temperate regions indicate that GHG emissions can be substantial, 11,12 and in some instances can rise to the level of a gas-fired facility.
The IPCC also reports that “hydropower plants without or with small storage may be susceptible to climate variability, especially droughts, when the amount of water may not be sufficient to generate electricity (Premalatha et al. 2014) (Section 6.5).15 Reliance on hydropower in times of drought also accelerates GHG emissions when depleted reservoirs necessitate the use of fossil fuels, particularly natural gas, to fill the gap.