Executive Summary
The Paul Scherrer Institute PSI developed an innovative instrument for analyzing Switzerland's energy transition 15 years ago with the Swiss TIMES Energy System Model (STEM). The model maps all relevant energy sectors – from electricity supply through transportation to buildings and industry – in an integrated and consistent structure. STEM has become an indispensable tool for science, policy, and interest groups today and is continuously expanded to address future challenges of the net-zero transition.
People
Topics
- Energy system modeling
- Swiss energy transition
- Decarbonization
- Renewable energy
- Carbon-free energy systems
- Energy policy
- Net-zero transition
Detailed Summary
The STEM model was initiated over 15 years ago by Kannan Ramachandran, who aimed for hourly temporal resolution – an innovative approach at the time. With support from the Federal Office of Energy (BFE) and despite limited computing resources and insufficient data, the team succeeded in developing a functional prototype in just two years. Evangelos Panos, now head of the Energy Economics group, contributed his expertise in operations research as a postdoctoral researcher.
The model today covers the entire Swiss energy landscape and spans temporally from 2010 to 2100. It maps electricity demand hourly and accounts for different weekdays and seasons. Advanced features include endogenous load profiles, system services markets, sophisticated generation unit dispatch planning, electricity transmission network constraints, and detailed consumer segmentation.
STEM is used by science, policy, and interest groups to answer key questions about the energy transition: decarbonization of electricity and transportation, integration of fluctuating renewable energy, efficient use of domestic biomass, and the strategic role of hydropower. The model is compatible with other analytical instruments such as general equilibrium models and life cycle assessments, enabling multi-perspective scenario development.
Since 2025, the model has contributed to the Energy Perspectives 2060, which determine Switzerland's long-term energy policy. The team has also developed tools applicable across Europe and city-level analytical instruments, which are applied in Basel, for example.
Key Messages
STEM is a state-of-the-art analytical tool for evidence-based energy policy in Switzerland and is internationally recognized as one of the leading technology-rich energy economics models
Comprehensive sector coverage: The model integrates electricity supply, transportation, buildings, and industry in consistent form with hourly temporal resolution
Political relevance: STEM supports decision-making on decarbonization, renewable energy integration, and strategic energy planning
Continuous development: Future versions will consider additional greenhouse gases (methane, nitrous oxide), macroeconomic feedback, and climate change impacts
International leadership: The model has inspired other countries; a national model for New Zealand is based on STEM principles
Stakeholders & Affected Parties
| Group | Role |
|---|---|
| Federal Office of Energy (BFE) | Primary funder and user for energy policy |
| Science & Research | Users for analysis and model development |
| Energy industry (Swissgrid, VSE, Swisselectric) | Stakeholders and funders |
| Political decision-makers | Users for evidence-based policy-making |
| General public | Indirectly affected by energy policy decisions |
| Industry & transportation sector | Affected by decarbonization measures |
Opportunities & Risks
| Opportunities | Risks |
|---|---|
| Scientifically sound, robust energy policy | Model complexity can lead to misinterpretations |
| Cost-effective and socially compatible energy concepts | Dependence on data quality and availability |
| Cross-sectoral and cross-regional problem-solving | Uncertainties in long-term forecasts (until 2100) |
| European and international applicability | Technological breakthroughs could overtake model predictions |
| Integration of macroeconomic effects | Political resistance to model recommendations |
Action Relevance
For decision-makers:
Use STEM as a planning instrument: The model should be systematically integrated into long-term energy planning processes, particularly for Energy Perspectives 2060
Prioritize expansions: Planned features (additional greenhouse gases, macroeconomic feedback) should be realized promptly
Ensure transparency and data availability: Continuous updating of technology and market data is essential for model quality
Stakeholder engagement: Regular exchange with industry, cantons, and municipalities on model findings
International collaboration: Leverage potential for European harmonization and exchange with other national models
Quality Assurance & Fact-Checking
- [x] Central statements and figures verified
- [x] Unconfirmed data marked with ⚠️
- [x] Sources and contact information validated
- [x] No identifiable bias or political one-sidedness
Verification status: ✓ Facts checked on January 19, 2026 (publication date)
Additional Research
Federal Office of Energy (BFE): Energy Perspectives 2060 – official energy policy and STEM integration
https://www.bfe.admin.chPaul Scherrer Institute – LEA: Laboratory website with publications and model details
https://www.psi.ch/de/leaSwissgrid: Role of renewable energy and electricity transmission networks in Switzerland's energy transition
https://www.swissgrid.ch
Bibliography
Primary source:
Press Release: "A Comprehensive Energy System Model for Switzerland" – Paul Scherrer Institute PSI
Published: January 19, 2026
Supplementary sources:
- Paul Scherrer Institute – Energy System Analysis Laboratory (LEA)
- Federal Office of Energy – Energy Perspectives 2060
- Swissgrid – Infrastructure and energy transition
Verification status: ✓ Facts checked on January 19, 2026
Footer (Transparency Notice)
This text was created with the support of Claude.
Editorial responsibility: clarus.news | Fact-checking: January 19, 2026