Introduction: what is fracking a case of? Theoretical lessons from European case studies

When we started to plan this special issue, shale gas extraction and hydraulic fracturing (“fracking”) as a technology and its related social conflicts seemed to be—except in very few countries, such as the United States—an environmental issue in a state of “fading away,” while still being of historical interest. However, things changed after Russia's full-scale invasion of Ukraine in February 2022. Beyond creating immense human suffering and massive destruction of Ukraine's infrastructures, the invasion has affected, and is affecting, distant countries, their peoples, and economies around the world, in various ways. One major issue at stake is the effect on energy markets and energy mixes in European countries, where strong dependencies on Russian fuels exist. Energy prices have skyrocketed, and several European governments (especially, Germany) had to reconsider their past politics of energy supply and transition. The war, so to speak, has unexpectedly opened a new window of opportunity for re-evaluating shale gas as a player in the energy transition (Teuffer 2022). This is mainly due to economic questions regarding energy prices, and political questions regarding energy autonomy and mixes