Modeling hydropower to assess its contribution to flexibility services in the Bolivian power system

Bolivia has an important hydroelectric potential that has the potential to be an important part of future energy supply. This potential is due to the topographic characteristics of the country, composed of two large hydrological systems, the Amazon and La Plata basin, with a power of 34,208.50 MW and 5,359.90 MW respectively. Hydropower has been increasing in the Bolivian territory in recent years, with a tripe objective: guarantee energy sovereignty, industrial development and the export of electrical energy. Today, the power system has a 33 % share of hydraulic component, a 61 % share of thermal component, and the rest of other renewable energy sources. Such a composition makes the system vulnerable to hydrological variations that can affect production costs and flexibility of the energy system. Therefore, this study aims to assess the effects of different rainfall years on the ability of hydropower to generate and store electricity. This is done using the hourly power system simulation software Dispa-SET, primarily developed by the European Commission. For the application of the methodology, the Dispa-Set Bolivia model is taken as a basis. For this study the hydroelectric systems are disaggregated by hydro unit, which allows to include the flows of sub-basins in run-of-the-river plants. The information on water inputs for different years is obtained from the Surface Water Balance of Bolivia 2017, which uses the Soil Moisture method (rainfall-runoff) through the software Water Evaluation and Planning (WEAP), for a period from 1980 to 2016. The model optimizes the system under all hydro years, both with a mid-term scheduling approach and a short-term optimal dispatch and unit commitment approach. Modeling has allowed to obtain a broad vision of different scenarios, where main results show that heavy rainfall years affect the electricity production of hydro plants by impacting the flexibility hydropower can provide to the system. This results in changes on the average production costs, which is quantified by differences in terms of electricity production of hydropower plants.