Although energy system models have become more complex, it does not necessarily mean that they are better suited to answer the questions, or address the challenges, faced by decision- and policymakers. In this report, we aim to tackle such critical issues and challenges of the European energy transition towards climate neutrality by 2050, with the user-driven updated SENTINEL modelling ensemble. Specifically, we showcase the applicability and usefulness of the SENTINEL modelling suite in the context of three case studies, a. a Continental level case study (European Union, Iceland, Norway, Switzerland, the United Kingdom, and some Balkan countries), b. a Regional level case study (Nordic countries), and c. a National level case study (Greece). Specifically, this report provides details on input data, as well as model linkages and results, and serves two purposes. It provides (i). detailed specifications for the application of the SENTINEL models in the context of policy-relevant scenarios and energy and climate targets, and (ii). answers to stakeholders’ critical research questions through scientific evidence from the SENTINEL models. Modelling results relevant to the power sector’s transformation showcase that the transition to a low-carbon power sector would need to consider potential lock-ins to intermediate technologies, such as natural gas, which could decrease European energy security, and increase import dependency. On the demand side, the potential for energy demand reduction in the European transport sector is large, while the industry sector presents inertia. However, electrification in both sectors is expected to become significant, which would decrease fossil-fuel extraction and use, and consequently direct fossil carbon dioxide emissions. Furthermore, achieving decarbonisation in the building sector by 2050 is possible but would require a higher annual rate of high-efficiency renovations and new buildings than currently prescribed, which would also require strong political support to accelerate the implementation of measures. Overall, increasing electrification across all demand sectors is expected to cause changes in total and hourly power demand, which could potentially increase peak demand. In this context, sector coupling can provide the necessary flexibility to the power system and ensure an adequate balance between energy supply and demand. Regarding the environmental impacts of the energy transition, we highlight that greenhouse-gas emission reductions should not be looked at solely, as the effect of the energy transition on other aspects (such as for example, human toxicity, human health, water depletion, particulate matter formation, terrestrial acidification, etc.) may be negative. On top of that, risks regarding the availability of critical raw materials should be taken into account to avoid scarcity of raw materials required for key new renewable technologies. Finally, on the socio-economic aspect, we show that although a people-powered, decentralised energy system has the highest system cost, it has the largest economy-wide welfare benefits, including positive aggregate EU27+ employment effects by 2030 and by 2050.

The authors would like to acknowledge the support from the EC. The authors would like to thank the SENTINEL colleagues that contributed to specific sections relevant to their models' application to the SENTINEL case studies. The content of this report is the sole responsibility of its authors and does not necessary reflect the views of the EC.