Methods and tools
To carry out its research, I-Tésé relies on a foundation of models, data, and quantitative approaches developed within the CEA or by partners.
Models
Within I-Tésé, a team is dedicated to modeling. The team's work contributes to improving, from an economic and quantitative perspective, the understanding of energy transition pathways and identifying the appropriate technological, political, and industrial strategies for achieving a sustainable, secure, and resilient energy future at the French, European, and global levels. To this end, the various projects involving the team concern energy-economy-environment modeling, supported by technical and economic expertise, and the implementation of scenario techniques to explore the transformation of energy systems.
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As a cross-disciplinary team within I-Tésé, it contributes to all of the laboratory's research themes, shedding light on the technological, economic, and environmental challenges of the energy transition, particularly in relation to:
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Energy markets and the dissemination of technological innovation
- The integration and flexibility of energy systems
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Resources for the energy transition
- Regulation, energy and environmental policies (prices, quantities), national and regional plans, etc.
In parallel with these activities, the team works cross-functionally to identify, develop, and integrate innovative modeling techniques aimed, in particular, at better understanding and interpreting complex models and scenarios, and informing public and industrial strategic decision-making in a more robust manner. To do this, it relies in particular on recent methods borrowed from operational research (including modeling under uncertainty), machine learning (for explainability), and high-performance computing.
The team maintains and develops several large-scale models for:
- Short-term analysis of the electrical system (UCED – Unit Commitment and Economic Dispatch), based on the
Antares model generator (several models).
- Long-term forecasting of the global energy system (multi-commodity, multi-regional, multi-sector), based on the
ETSAP-TIMES and
Energyscope model generators (several models); or coupled energy systems (e.g., electricity and heat), based on the
CAIRN model generator.
We also works on the development of ad hoc models, for example real options or international trade in energy commodities, using commercial tools (GAMS, CrystalBall) or open-source tools.
Special focus
EnergyScope is an open-source and open-data energy system model developed by various research institutes. At I-Tésé, it is used in particular for Circular Carbon Economy (CCE) issues, as it allows carbon flows in the energy system to be tracked.
Thesis: “Complementarity between CO2, biomass, and hydrogen for the production of e-biofuels.”
Thesis: “Impacts of massive renewable carbon mobilization on biogeochemical cycles and ecosystem services.”
In order to carry out certain studies, I-tésé wanted to have a market model of the European electricity system. The ESMOD model, which stands for European Electric System Modeling, has therefore been developed by Itésé since 2019. This model is based on data from European studies (ERAA and
TYNDP) by European network operators (ENTSO-e) and the open-source software
RTE ANTARES Simulator.
In general, market simulation tools are not designed to model the behavior of market players or optimal auctions, but rather to simulate the marginal costs of the entire system and different market areas. The main assumption is that the market is perfectly competitive and that there is no strategic behavior. As a result, marginal costs are representative of prices.
The market is modeled as a perfect wholesale market, as if all energy were sold on a daily basis. Thus, the tools calculate marginal costs as part of the result of a system cost minimization problem. This mathematical problem, also known as “Optimal Unit Commitment and Economic Dispatch” (UCED), is often formulated as a large-scale mixed-integer linear programming (MILP) problem. In other words, the program attempts to find the least costly solution while respecting all operational constraints (e.g., power ramps, minimum ramping times, transfer capacity limits, etc.). In order to avoid unfeasible solutions, constraints are very often modeled as “soft” constraints, i.e., potentially violated at the cost of a high penalty in terms of cost.
In addition to taking into account constraints related to production resources, these tools can also integrate power grid constraints with varying levels of detail. Currently, for regional or pan-European market studies, the standard approach is based on market coupling based on net transfer capacity (NTC). This means that grid constraints are not modeled in detail, but are simply represented as limits on electricity exchanges between different market areas (e.g., limit on electricity exchange capacity between France and Spain).
Today, the ESMOD model is used, among others, within Itésé to study the flexibility of the French nuclear fleet, the effect on the electricity system of changes in electricity demand profiles by 2050, and infrastructure needs based on the development of hydrogen demand.
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Development of skills in TIMES-type bottom-up prospective modeling
The global challenges of this century, particularly in terms of energy and the environment, require long-term decisions to be made in an increasingly complex, uncertain, and rapidly changing environment. To meet this need for foresight, prospective modeling remains a valuable tool for supporting public and private decision-makers by shedding light on possible futures. However, these tools must also evolve to best respond to the new questions and needs they face.
The TIMES project addresses both the relevance of methods and the impact of results. Its main objective is to study the transformation of energy systems from a global and holistic perspective, examining the economic, environmental, and strategic relevance of energy technologies and resources in the context of the necessary decarbonization of the global economy. It will need to place increasing importance on impact transfers (particularly resources), new constraints (geopolitical), market imperfections, and uncertainty. To this end, it will implement innovative methods derived from operational research and machine learning, engineering, and economics, to help develop tools and produce tangible and robust economic analysis elements to aid decision-making.
This project is based on the
TIMES (The Integrated MARKAL-EFOM System) model, a technical and economic model for optimizing energy systems developed by the International Energy Agency through the Energy Technology System Analysis Program (ETSAP). The approach to modeling energy systems is bottom-up. It provides a fairly accurate and detailed technological representation with a modular structure of integrated energy markets (resource, conversion, transport-distribution, storage, and end-user modules).
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Developments in system dynamics
The dynamics of complex systems emerged in the late 1950s at MIT (Massachusetts Institute of Technology) under the leadership of Professor Jay Forrester, based on the similarity between the economic and/or financial behavior of companies on the one hand, and physical and electronic control systems on the other, transposing the techniques used to analyze physical phenomena to the business world.
At the heart of complex systems are feedback loops. These describe how one variable impacts another, which in turn affects the initial variable: positive feedback amplifies phenomena, while negative feedback contributes to regulation.
Of course, as soon as interconnections between loops appear, or if certain relationships between variables involve delays or non-linear elements, the effects become counterintuitive. Hence the approach of modeling complex systems using software such as
STELLA and
VENSIM.
Models can take into account a wide variety of variables: physical, economic, financial, sociological, psychological, and physiological, both quantitative and qualitative. Here are some examples of phenomena that can be modeled using system dynamics:
- Economic cycles: Fluctuations in the economy, such as recessions and periods of growth.
- Ecosystems: Interactions between species in an ecosystem, such as predation and competition.
- Control systems: Regulatory mechanisms in machines and industrial processes.
- Disease spread: How diseases spread in a population and the effects of public health interventions.
- Resource management: Sustainable exploitation of natural resources, such as forests and fish.
At I-Tésé, complex systems dynamics is currently used primarily for resource issues in both the nuclear sector (uranium and plutonium) and the battery sector (lithium, cobalt, etc.).
Databases
The CEA has set up a platform for technical, economic, and LCA (Life Cycle Assessment) data on energy sectors: the ABTEC platform. It centralizes technical, economic, and environmental data on the main energy sectors studied at the CEA, drawn from national and European projects and ongoing bibliographic research on these sectors.
ABTEC was developed with the contribution of experts from I-Tésé, LITEN, IRESNE, ISEC, ISAS, and PRTT Occitanie (regional technology transfer platform). Designed to facilitate the capitalization of knowledge and the harmonization of analyses, ABTEC is now the common reference for all CEA teams involved in energy studies. ABTEC data is already being used in numerous national and European projects.
Each year, the ABTEC team publishes a new, updated edition, incorporating technological, economic, and geopolitical developments in the global energy sector.
The data is rigorously validated according to a process approved by the Scientific Council of the DES, the CEA's Energy Directorate.
Econometrics
Discrete choice experiments (DCE)
I-Tésé uses this method, derived from economics, to infer individuals' willingness to pay or accept, i.e., the monetary value they place on the various attributes of a choice (price, time, CO₂ emissions, etc.). It consists of presenting participants with several scenarios composed of options with varying characteristics. By observing their choices, this method also makes it possible to quantify price and cross-elasticities, measuring how variations in attributes influence decisions. DCEs can also incorporate latent variables, which are psychological factors that are not directly observable, such as individuals' perceptions or motivations. These latent variables, derived from psychology, complement measurable attributes and provide a better understanding of why real decisions may differ from purely economic theoretical models. By taking these hidden dimensions into account, DCE provides a more detailed view of behaviors, which helps to design more appropriate and accepted public policies.
I-Tésé, in collaboration with the TRAVEL Chair, is conducting a discrete choice study that analyzes long-distance transportation preferences. This economic and behavioral analysis approach integrates both latent variables related to individual perceptions and objective attributes such as cost, travel time, and CO₂ emissions to shed light on the trade-offs made by travelers.
Impact assessment
Impact assessment aims to measure the direct, ex post effect of a policy or program on an economic phenomenon by establishing a robust causal link. It is essential for evaluating the effectiveness and fairness of existing mechanisms, particularly when participation is not random but influenced by factors that are difficult to observe. This method seeks to establish a robust cause-and-effect relationship using techniques such as double differences or instrumental variable regression, which make it possible to isolate the specific impact of the action.
I-Tésé is conducting a study on the causal effect of the expansion of renewables and cross-border trade in France on electricity prices, production from other technologies, and emissions (work in progress).
Non-causal econometrics
This statistical approach studies correlations or associations between economic variables without necessarily being able to establish a causal relationship. It is used to analyze trends, make forecasts, or describe behaviors based on observed data, but does not allow for direct conclusions about causal effects.
At I-Tésé, a thesis on the analysis of the integration of intermittent renewable energies across different dimensions (volume, price level, and volatility) of electricity balancing markets (intraday and reserves) is currently underway.
Stakeholder implications
I-Tésé is committed to involving stakeholders in its research. This is reflected in particular through:
- behavioral economics experiments
- field surveys
- participatory science workshops (Living Lab approach)
Field surveys and participatory science workshops
Field surveys or participatory science workshops are carried out by partners or service providers as part of specific projects. Examples include:
- the SISYPHE study: a survey of more than 70 French and European manufacturers was conducted to better understand the dynamics of European demand for low-carbon electrolytic hydrogen between now and 2040. These surveys were conducted by our researchers and a service provider.
- The Prométhée observatory: household surveys and participatory science workshops conducted at the Dôme de Caen were set up to better understand how people are adapting to energy crises and possible ways to promote energy efficiency. These surveys and workshops were conducted by the team of sociologists from the CERREV laboratory at the University of Caen, partners of I-Tésé within the framework of Prométhée. I-Tésé participated in several workshops.
- The SPECULAR project: one of the key aspects of the SPECULAR project (PEPR SPLEEN: industry decarbonization options based on energy efficiency) is the involvement of a wide range of stakeholders in the decarbonization process, including industry leaders, public policy makers, and transition activists. These stakeholders will be mobilized through field surveys for case studies, the implementation of the Living Lab approach to enhance the operationality of the results, and the creation of a stakeholder committee. The surveys and Living Labs are set up and supervised by teams of sociologists from the CERREV laboratory at the University of Caen and Mines Paris, I-Tésé's partners in the project. I-Tésé will participate in workshops and the construction of interview grids, as well as their analysis.
Behavioral economics
In addition, I-Tésé studies the behavior of stakeholders (households, businesses, public authorities) in order to understand and anticipate their decisions in the energy system through behavioral economics experiments.
Analysis of the regulatory and legal corpus
Legal research at I-Tésé aims to analyze how the law can support and regulate societal changes related to the energy transition, particularly energy efficiency.
It is based on a dual approach.
- On the one hand, an in-depth and systematic analysis of legal texts—national, European, and international—enables the identification, classification, and characterization of the various regulatory instruments used in order to understand their logic, objectives, and consistency.
- On the other hand, the research focuses on studying the effectiveness of these standards, i.e., their concrete implementation and real impacts, using empirically-inspired methods derived in particular from the sociology of law.
This work also draws on innovative interdisciplinary approaches, combining law with other fields of knowledge such as economics, political science, and modeling. These cross-disciplinary approaches make it possible to evaluate the concrete effects of legal instruments, examine their consistency with other public policies, and devise new regulatory tools adapted to energy efficiency objectives.
Thus, legal research in this field is not limited to a theoretical study of texts, but participates fully in a collective effort to analyze and design legal frameworks capable of supporting the transition to a more energy-efficient and sustainable society.
Open Source Intelligence
One of the institute's objectives is to provide forward-looking insights and analysis to consolidate the organization's research strategy in the field of energy and inform public and private decision-makers. Observing and analyzing trends and developments in the field of energy transition is therefore of paramount importance to the institute. That is why a monitoring system on this subject has been in place since September 2022.