Life cycle assessment of run-of-river hydropower plants in the Peruvian Andes: a policy support perspective

Abstract

Purpose: Low-carbon emissions are usually related to hydropower energy, making it an attractive option for nations with hydropower potential as it enables them to meet increasing electricity demand without relying on burning fossil fuels. In fact, the new wave of hydropower plant construction is occurring mainly in tropical areas where an additional environmental impact must be considered: biogenic greenhouse gas (GHG) emissions due to the degradation of biogenic carbon in reservoirs. Peru is planning to install up to 2000 MW in hydropower until 2021, but the input and output flows, as well as the environmental impacts that these generate, have not been explored. Hence, a set of three hydropower plants built in the past decade located in the Peruvian Andes were analyzed from a life cycle perspective. The main objective of the study is to generate detailed life cycle inventories for each of these three hydropower plants with the aim of obtaining specific information for current conditions in Peru. Methods: The life cycle assessment methodology was applied to compute the environmental impacts. Data collection was based mainly on primary data obtained directly from the hydropower companies, although biogenic emissions were modeled considering local net primary productivity conditions and other site-specific conditions. Although the calculation of GHG emissions related to hydropower plants was a priority, considering the important policy implications of decarbonizing the Peruvian electricity grid, other environmental categories, such as eutrophication or the depletion of abiotic resources, were also considered. The IPCC method was used to calculate GHG emissions, whereas a set of eight additional impact categories were computed using the ReCiPe 2016 method. Results and discussion: Results show that GHG emissions per unit of electricity generated were in the lower range of emissions observed in the literature, in all three cases below 3 g CO2eq/kWh. Biogenic emissions represented less than 5% of the total GHG emissions despite their location in a tropical nation, due to the arid conditions of the landscape in the Andean Highlands, as well as the mild temperatures that are present in the reservoirs. In terms of stratospheric ozone depletion, a GHG with ozone depletion properties, N2O, was the main source of impact. Conclusions: The results are intended to be of utility for an array of applications, including relevance in decision-making in the energy sector and policy-making at a national level, considering the implications in terms of meeting the nationally determined contributions to mitigate climate change in the frame of the Treaty of Paris.