Abstract

ZURITA, María Mercedes  and  LUJAN, Marcos. Models for estimating GHG emissions in hydroelectric reservoirs and application to three hydroelectric projects in Bolivia to obtain sustainability indicators applicable to the Environmental Impact Assessment. RevActaNova. [online]. 2023, vol.11, n.2, pp.140-161.  Epub Nov 30, 2023. ISSN 1683-0789.  https://doi.org/10.35319/acta-nova.20235.

In response to the climate crisis, Bolivia has adopted the energy transition by harnessing hydroelectric energy as the main source. Thanks to its climatic and topographic conditions, the country has an approximate potential of 40 GW, although its current hydroelectric generation capacity is only 0.75 GW.

This article presents the results of a research on different models for estimating GHG emissions in hydroelectric projects that allow the estimation of these emissions in different biogeographic contexts and allow establishing the conditions of the reservoir and the climatic conditions that affect GHG emissions. Power density (power generated per unit of flooded area) and specific emissions (GHG emissions per energy generated) were identified as the main sustainability indicator variables. Among the models used, the G-res Tool model was selected to estimate greenhouse gas (GHG) emissions in three hydroelectric projects in Bolivia: Ivirizu, Miguillas and Misicuni in a 100-year life cycle. The Ivirizu Hydroelectric Project generates 374 t CO2eq year-1 from biogenic sources and emits approximately 664,664 t CO2eq during its construction phase, resulting in a net GHG footprint of 711,506 t CO2eq and a specific emission of 6.13 g CO2eq kWh-1. In the case of Miguillas, biogenic emissions from the reservoir were estimated at 239 t CO2eq year-1, while the emissions associated with the construction were estimated at 412,654 t CO2eq, the specific emissions being 4.14 g CO2eq kWh-1. For the Misicuni Multiple Project, 299 t CO2eq year-1 were estimated in biogenic emissions, for the construction stage 974,448 t CO2eq were estimated, resulting in a net GHG footprint of 974,747 t CO2eq, the specific emissions would be 6.95 g CO2eq kWh-1. These results clearly show that GHG emissions during construction activities significantly exceed biogenic GHG emissions from flooding of the reservoirs of the three hydropower projects. Furthermore, it is important to highlight that there is variability in the values due to the specific environmental conditions of each location. Ivirizu has a greater amount of biogenic GHG emissions because it is in a temperate zone, with periods of elevated temperatures and is home to a dense forest at the reservoir site. In the case of Miguillas, the area is temperate, and the soil cover is made up of wetlands. As for Misicuni, its location in a cold mountain climate, where previously an area of grassland predominated. Due to their specific emissions of less than 80 g CO2eq kWh-1, all of these projects are considered environmentally sustainable.

Keywords : GHG emissions; hydroelectric project; G-res Tool.

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