The requirements made on energy system models have changed during the last few decades. New challenges have arisen with the implementation of high shares of Renewable Energies. Along with the climate goals of the Paris Agreement, the national greenhouse gas strategies of industrialized countries involve the total restructuring of their energy systems. In order to archive these climate goals, fitted and customized models are required. For that reason, this paper focuses on national energy system models that incorporate all energy sectors and can support governmental decision making processes. The reviewed models are evaluated in terms of their characteristics, like their underlying methodology, analytical approach, time horizon and transformation path analysis, spatial and temporal resolution, licensing and modeling language. These attributes are set in the context of the region and time in which they were developed in order to identify trends in modeling. Furthermore, the revealed trends are set in the context of current challenges in energy systems modeling. Combining specified research questions and specific greenhouse gas reduction strategies, this paper will help researchers and decision makers find appropriate energy system models.

A review of current challenges and trends in energy systems modeling

Large-Scale decision-making: Characterization, taxonomy, challenges and future directions from an Artificial Intelligence and applications perspective

Trade-Offs between Geographic Scale, Cost, and Infrastructure Requirements for Fully Renewable Electricity in Europe

Power-to-hydrogen as seasonal energy storage: an uncertainty analysis for optimal design of low-carbon multi-energy systems

Characterization of input uncertainties in strategic energy planning models

Strategic energy planning for large-scale energy systems: A modelling framework to aid decision-making

Optimal use of biomass in large-scale energy systems: Insights for energy policy

Woody biomass, a renewable energy resource, accumulates solar energy in form of carbon hydrates produced from atmospheric CO2 and H2O. It is therefore a means of CO2 mitigation for society as long as the biogenic carbon released to the atmosphere when delivering its energy content by oxidation can be accumulated again during growth of new woody biomass. Even when considering the complete life cycle, usually, only a small amount of fossil CO2 is emitted. However, woody biomass availability is limited by land requirement and therefore it is important to maximize its CO2 mitigation potential in the energy system. In this study, we consider woody biomass not only as a source of renewable energy but also as a source of carbon for seasonal storage of solar electricity. A first analysis is carried out based on the mitigation effect of woody biomass usage pathways, that is the avoided fossil CO2 emissions obtained by using one unit of woody biomass to provide energy services, as alternative to fossil fuels. Results show that woody biomass usage pathways can achieve up to 9.55 times the mitigation effect obtained through combustion of woody biomass, which is taken as a reference. Applying energy system modelling and multi-objective optimisation techniques, the role of woody biomass technological choices in the energy transition is then analysed at a country scale. The analysis is applied to Switzerland, demonstrating that the use of woody biomass in gasification-methanation systems, coupled with electrolysers and combined with an intensive deployment of PV panels and efficient technologies, could reduce the natural gas imports to zero. Electrolysers are used to boost synthetic natural gas production by hydrogen injection into the methanation reaction. The hydrogen used is produced when there is excess of solar electricity. The efficient technologies, such as heat pumps and battery electric vehicles, allow increasing the overall efficiency of the energy system while generating demand for the solar electricity.

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On the Assessment of the CO2 Mitigation Potential of Woody Biomass

We develop an energy calculator within an online teaching platform to aid citizens and decision-makers understanding an energy system. The model, designed in order to be easily adapted to any energy system at national or regional scale, is presented and applied to the case of Switzerland. Although autonomous on a yearly balance, Switzerland today already relies on foreign imports to face higher electricity demand in winter months. The decision of the country of phasing out nuclear power by 2034 will have as a consequence to further increase this seasonal electricity deficit. The Swiss-EnergyScope.ch project is a contribution to the public debate escalated concerning Switzerland's future energy strategy, helping citizens to take an active part in it by associating numbers and facts to opinions and choices. The online platform mainly consists of an energy calculator, enabling users to evaluate the effect of a list of possible choices on the energy future of the country. An online wiki and a MOOC will allow users to acquire basic knowledge on energy and to be guided through the learning process and the use of the calculator itself. The robust conceptual design strategy adopted to model the Swiss energy system allows for the contextualization of the key issue of electricity supply within the framework of the overall energy system, conveying a holistic view in which technologies affecting both heat and electricity (such as heat pumping and cogeneration) can be easily integrated. The monthly approach used for the calculation and display of data allows highlighting the central role of seasonal fluctuations in supply and demand. Overall, the designed tool and the associated learning experience allow popularizing energy issues, demystifying the complexity of a national energy system without oversimplifying it.

Victor Codina Gironès

Papers

Characterization of input uncertainties in strategic energy planning models

Strategic energy planning for large-scale energy systems: A modelling framework to aid decision-making

Optimal use of biomass in large-scale energy systems: Insights for energy policy

On the Assessment of the CO2 Mitigation Potential of Woody Biomass

Swiss-EnergyScope.ch: a Platform to Widely Spread Energy Literacy and Aid Decision-Making