"It's not about denouncing, but about reminding that Switzerland must take action"
Interview with Nadine Brauchli, Nadine Brauchli, Head of Energy at the Association of Swiss Electricity Companies (AES).
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Which path to a CO₂-neutral and independent Swiss energy system?
Relying on an innovative methodological framework for modeling energy transitions, the study published in 2023 in the journal "Frontiers" presents a vision of the national energy system.
3 min read
During September, the National Council adopted a motion instructing the Federal Council to develop a comprehensive energy storage strategy. This initiative aims to coordinate various solutions — such as pumped-storage hydroelectricity, decentralized batteries, thermal storage and Power-to-X technologies — in order to better integrate renewable energies, reduce energy losses and strengthen supply security as well as the stability of the Swiss electricity grid.
This decision provides an opportunity to revisit a study published in 2023 in the journal "Frontiers", a study that proposes a future model for the national energy system. Entitled "On the role of energy infrastructure in the energy transition : Case study of an energy independent and CO₂-neutral energy system for Switzerland", it is based on an innovative methodological framework for modelling energy transitions.
The study notably analyzes the country's energy situation in 2020, then assesses the investments and reinforcements required to achieve carbon neutrality and energy independence by 2050. It also examines the technical constraints of the grid, their influence on technology choices, as well as the interactions between solar and wind production and their effects on the stability of the electrical system. Its summary in a few key points:
1️⃣
The model is applied to a Swiss case study aiming for a transition to a carbon-neutral and energy-independent system by 2050, without recourse to nuclear power. Based on a monthly resolution and a national average approach, it does not take into account regional differences in terms of potential or energy demand. Carbon neutrality is ensured by a net-zero CO₂ emissions constraint, while energy independence is guaranteed by the total absence of resource imports. The case study results are represented in a cost and energy diagram illustrating the performance of the different technologies.
2️⃣
The study shows that grid reinforcement — particularly of low and medium voltage networks — is essential to enable a massive deployment of photovoltaics (PV) and wind. To minimize costs while meeting demand, the model favors efficient technologies powered by intermittent renewable energies. The energy produced must be transported or stored, which may sometimes require grid reinforcement when their capacity is exceeded.
3️⃣
The analysis also highlights significant trade-offs between renewables, storage and infrastructure. In 2050, the targeted Swiss system is CO₂-neutral and independent, with 15.4 GW of photovoltaics and 20 GW of wind, implying a reinforcement of the low-voltage network in summer and of the medium-voltage network in winter. The optimal mix combines methane for industry and heating, and hydrogen for heavy transport, with centralized seasonal storage (up to 6 TWh of methane and 8.9 TWh hydraulic). In the case of limited reinforcement, the model is compensated by increased use of biomass and less efficient technologies, which may lead to a cost increase of up to 16%.
4️⃣
The authors point out several limitations to their analysis. Their model relies in particular on a monthly temporal resolution, which does not allow detailed modelling of short-term dynamics (such as daily storage cycles). It is mainly based on a spatial aggregation assuming that energy production and consumption take place at the same point. This assumption ignores the increasing decentralization of the energy system, such as that of smart buildings and neighbourhoods (RCPv and future CEL), which can overestimate distribution network needs.
"Of course, this is only a model, and one possible path among others," recently noted Yasmine Calisesi, Director of the Energy Center at EPFL, in a LinkedIn post. Over the years to come, depending on geopolitical and macroeconomic developments, and depending on the delays that Switzerland may accumulate in its transition, this model will have to be adjusted and refined.
The essential point, the study emphasizes, is that the success of the energy transition will depend on a rigorous consideration of the constraints and costs related to infrastructure, and not only on production technologies or climate objectives. "Choices about the deployment and development of new infrastructure for current energy systems must be cautious and framed in a long-term perspective, because future generations will pay the consequences of hasty decisions," the authors state in conclusion.
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