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Energy Optimization and Environment

The main characteristics of the Brazilian electrical system are: continental dimensions; high energy consumption growth rates; large share of renewable sources, with the predominance of hydroelectricity, and increasing participation of so-called new renewable sources, such as wind and solar. Additionally, it presents a relevant hydrological, temporal and spatial diversity, allowing energy complementary among the several regions of the system. These characteristics have motivated Cepel to develop and maintain in the state of the art an innovative and integrated chain of methodologies and computational tools for energy optimization, water resources and environment, which guide the expansion and operation planning of the Brazilian power generation system. Such models are currently developed under the Energy Optimization and Environment Department (DEA) of CEPEL.


This set of methodologies and computational programs - based on optimization, simulation and statistical techniques, takes into account the stochastic nature of many variables (mainly, hydro inflows to reservoirs and generation of intermittent sources) and integrates the long, medium and short-term horizons, enabling the definition of a coordinated expansion and operation planning of the electric system on a sustainable basis. Some of these models are officially used by the Ministry of Mines and Energy (MME), sectorial Institutions such as the National Electric Energy Agency (ANEEL), Energy Planning Company (EPE), Independent System Operator (ONS), the Operator of Brazilian Electric Energy Market (CCEE), as well as Eletrobras System Companies, electric distribution utilities and other agents of the power sector.   Some activities of the Brazilian power sector that are officially performed with the use of such models are:  


  • •    Hydropower Inventory Studies of River Basins by power system companies, with the SINV model;
  • •    Preparation of the 2030 National Energy Plan, with the MELP model;
  • •    Preparation of the 10-year Energy Expansion Plan, assured energy calculation of generation projects, preparation of guidelines for energy auctions provided by EPE, with the aid of NEWAVE and SUISHI models;
  • •    Preparation of the Energy Operation Plan (PEN) by ONS, with the NEWAVE model;
  • •    Determination of the Monthly Operation Program (PMO) by ONS and the wholesale Energy Prices (PLD) by CCEE, on a weekly basis and in three load blocks, with the application of NEWAVE, DECOMP, GEVAZP, PREVIVAZ, SPEC, OPCHEN, PREVCARGAPMO models, as well as the MODCAR feature of the CONFINT model;
  • •    Elaboration of the Annual Plan for flood prevention and the flood control operation scheme by using the SPEC system, as well as the OPCHEN, OPCHEND and OPCHENS models;
  • •    Elaboration of the study entitled "Greenhouse gases emissions - 2050: Economic and social consequences of the Government Plan scenario", by the Centre of Integrated Studies on Environment and Climate Changes (Centro CLIMA/COPPE/UFRJ), with the aid of the MATRIZ program.


In general, these models undergo a wide and open validation process, with the participation of many institutions, utilities and agents, and their use must be approved by ANEEL and CPAMP - Permanent Commission for Analysis of Methodologies and Computation Programs of the Electric Sector, coordinated by MME and related to the National Council of Energy Policy (CNPE).


Based on hydropower inventory studies and demand projection analyses, which can be done by using SINV and PREVMERCADO tools, respectively, long term expansion planning studies can be performed, integrating not only the electrical power and natural gas sectors, but energy planning as a whole, with the aid of MELP and MATRIZ models, respectively. The main goal of these studies is to derive a strategy for the expansion of power generation plants and interconnections among system areas, taking into account the interdependency among different energy chains in an economic way, but also considering reliability and environmental aspects. The outputs of these simulations provide important information for mid and short term expansion planning studies performed with NEWAVE and SUISHI models, in an iterative way with the MELP model, with the objective of obtaining a list of candidate generation and transmission projects to be built, which can be contracted through public auctions.


Some of the models developed in the DEA department carry out the transition from expansion to the operation planning and scheduling, with a horizon ranging from 5 years to weeks, in monthly, weekly and hourly time steps. The use of these optimization/simulation models ensures an optimal and coordinated operation of the Brazilian power system, with the aim of minimizing system operation costs but taking into account risk measures to guarantee the security of supply. NEWAVE and DECOMP models are used for long, mid and short term operation planning studies. For these tasks, other models are also used such as: PREVIVAZ for the inflow forecast and GEVAZP for the generation of energy/water inflow scenarios for the hydro plants; SPEC/OPCHEN for flood control; PREVCARGAPMO for load forecast and CONFINT model for reliability analysis, which contain special modules to determine the load duration curves for the operation planning models. For the daily operation scheduling on an hourly basis, the DESSEM model is currently being validated by ONS and CCEE, on a set of so-called "shadow" runs in order to be prepared for official use starting in January 2020. For this task, the OPCHEND model can also be used for flood control and the VENTOS program to obtain probabilistic wind generation forecasts. For real time operation, the ISELF load forecast model can be used. Finally, CEPEL has been developing a set of methodologies to take into account the uncertainty on the generation of intermittent sources in all hierarchical levels of operation and expansion planning.


From the environmental perspective, CEPEL develops methodologies to incorporate socio-environmental aspects in all phases of generation and transmission expansion planning, as for example in the hydropower inventory studies (SINV project) to improve the decision making process to chose the best alternatives through a multicriteria analysis. In this sense, one of the main results was the inclusion of the integrated environmental assessment in the 2007 revision of the Manual for Hydropower Inventory Studies of River Basins. In the context of the AAEXP project, the AMBIENTRANS model applies geoprocessing techniques and tools that are available in the LABGIS laboratory in order to determine the best routes for transmission line corridors in terms of least environmental impact. Methods, criteria and indicators for Corporate Sustainability Management are also developed and the IGS software - which is used by all companies of Eletrobras group - allows the storage, edition, assessment, monitoring and report of all these indicators. Another highlight in the department is the BALCAR project which, in partnership with companies of the Eletrobras group and several universities, aimed to develop a methodology to compute the net emission of greenhouse gases (GHG) in the hydro reservoirs. The application of the methodology for a set of eight hydro projects spread in different regions helped to demystify the erroneous concept that plants in tropical regions have a high level of GHG emissions, and clarify that the emission level is similar to those in boreal regions. Moreover, CEPEL also develops the EMISFERA corporative tool, used for the computation of GHG emissions power companies, as well as methodologies and criteria for the measurement, modeling and management of GHG emissions in reservoirs.


Still with focus on the sustainable development of hydropower, CEPEL recently proposed in the UHPLAT project a methodology to incorporate environmental conservation measures in the surroundings of a hydropower project, with the aim of minimizing the environmental impact in order to make hydropower generation compatible with socio-environmental policies. The work was developed for the Mines and Energy Ministry of Brazil and the World Bank under the META project, and its main target was the construction of hydro plants in areas with very low anthropic occupation, as in the Amazonia region of Brazil.


The energy planning models of CEPEL have oriented the expansion and operation of the Brazilian electricity system on a sustainable basis, with a high share of renewable sources, such as hydroelectric and biomass, and more recently, wind and solar. Due to its intrinsic nature, it has also contributed to the elaboration of mitigation actions, especially those related to strategies to implement low carbon technologies, with the consequent reduction of greenhouse gas emissions. On the other hand, there is a worldwide growing concern related to global warming - or climate change, and the impacts that the increasing levels of GHG emissions of anthropogenic origin may cause on climate; it is also important to assess how variations in temperature, changes in rainfall patterns and the occurrence of extreme weather events can impact the energy sector in terms of demand, energy supply, infrastructure and energy assets. In order to address these issues, CEPEL has been developing the comprehensive Climate Change Project - MUDCLIMA, which aims at developing methodologies to narrow the gap between climate and energy simulation/optimization models. This project encompasses the following aspects: (i) elaboration and analysis, from the IPCC's Representative Concentration Pathways (RCPs), of inflow scenarios to the hydropower plants by 2100, including extreme events; (ii) development of methodologies to consider their impacts in the power system expansion and operation planning, in terms of economy, security and emissions of greenhouse gases, also considering the associated effects on mitigation and adaptation policies; (iii) development of strategies and actions to adapt to the effects of climate change in the social, ecosystem and business areas; and (iv) development of methodologies for the establishment of indicators related to adaptation and resilience for the eligibility of hydropower projects to climatic bonds.


The DEA department also develops tools and methodologies capable of supporting the investment decisions in generation and transmission projects. The main product of this project is the ANAFIN model, used to determine the economic and financial viability of new power transmission and generation projects, such as wind, solar PV, hydro and thermal generation from natural gas, coal, oil and biomass, taking into account the uncertainties related to each candidate project. In the context of ECOMERC project, CEPEL also develops studies related to energy trading.   Parallel processing, high performance computing and cloud computing techniques have been used in some of the energy planning models of CEPEL to speed up their cpu times. Such reduction in the execution time allows to enhance the modeling of components and to refine the time frame in those optimization tools. Under the LIBS project, CEPEL has been developing algorithms and computational scripts to improve the coding, interface and data base of all the models. The main target of the project is to provide a unified framework of input files, output files and database entries, in order to allow integrated studies using these models to be performed in an easy and suitable way, on a web interface environment.  

Figure 1 – Flow chart showing the integration of research Project and tools developed in the DEA department for the expansion and operation planning of energy systems.

The associated Research Lines of the department are:  

  • • Energy Expansion Planning:
    • o   Generation Expansion Planning;
    • o   The Sustainable Development of Hydroelectricity;
  • • Energy Operation Planning:
    • o    Long and Mid Term Power Generation Planning;
    • o    Short-Term Hydrothermal Scheduling and dispatch;
  • •  Environment;
  • •  Stochastic Hydrology and Water Resources;
  • •  Integration of intermittent sources and storage devices;
  • •  Financial Analysis of Projects and Energy Trading;
  • •  Computational Tools Applied to the Energy Planning Models.