Rapidly transitioning to clean and sustainable energy

I am an interdisciplinary researcher in renewable energy and environmental science, heading the Sustainable Energy Systems Unit in the Climate Policy Group at ETH Zürich’s Department of Environmental Systems Science. Our research is on the global transition to a 100% clean and renewable energy system, and the technical, economic and policy barriers on the way to that goal.

Research spotlight
Photovoltaic electricity is a no-regrets investment in Europe irrespective of climate change

Results for present yearly total PV potential and future relative change and variance compared to the present under the RCP8.5 climate change scenario. Maps show the ensemble mean of the CMIP5 models of the total PV potential (a) for the present (2007–2027), (b) relative difference in yearly sum of produced power, and (c) intra-annual (seasonal) variance between the present (2007–2027) and future (2060–2080) time periods. Adapted from Müller, Folini, Wild and Pfenninger (2019).

Photovoltaic power output changes locally by −6% to +3% on annual and −25% to +10% on monthly scales, when comparing present (2007-2027) to future (2060-2080) with a CMIP5 climate model ensemble for the RCP8.5 climate change scenario. Southern Europe sees increased output, while northern Europe sees a decrease; overall, photovoltaic electricity is a no-regrets investment in Europe irrespective of climate change. → Müller, Folini, Wild and Pfenninger (2019).

Open code and data

In the course of my work I created and lead development of the open-source energy system modelling tool Calliope. I am also the creator and lead developer of the Renewables.ninja platform to simulate wind and solar power plants worldwide. I am a member of the Open Energy Modelling Initiative, which promotes openness and transparency in energy system modelling, and of the Open Power System Data project, which provides a free and open data platform for power system modelling.


You can contact me by email. I am always interested to speak to enthusiastic students looking for thesis projects or research experience. Get in touch by email with a CV and some detail on your research interests.

Recent publications

  • CMIP-5 models project photovoltaics are a no-regrets investment in Europe irrespective of climate change. Johannes Müller, Doris Folini, Martin Wild, Stefan Pfenninger. (2019). Energy. doi: 10.1016/j.energy.2018.12.139
  • Calliope: a multi-scale energy systems modelling framework. Stefan Pfenninger and Bryn Pickering. (2018). Journal of Open Source Software. doi: 10.21105/joss.00825
  • Impacts of Inter-annual Wind and Solar Variations on the European Power System. Seán Collins, Paul Deane, Brian Ó Gallachóir, Stefan Pfenninger, Iain Staffell. (2018). Joule. doi: 10.1016/j.joule.2018.06.020

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