Overview of CERN strategies for the reduction of greenhouse gas emissions from particle detectors

A set of gaseous detectors used in high-energy particle physics experiments operate with gas mixtures containing greenhouse gases such as C$_2$H$_2$F$_4$, CF$_4$, C$_4$F$_{10}$, and SF$_6$. Given their high Global Warming Potential and increasingly stringent European regulations regarding the use and trade of these gases, various strategies have been implemented by the CERN Gas Team to reduce the emissions of greenhouse gases resulting from detector operation. The first strategy involves the design, construction, operation, and continuous optimization of gas recirculation plants, which theoretically allow for up to a 100% reduction in emissions. However, due to constraints in detector operation, the recirculated fraction is typically around 90%, meaning some gas is still exhausted from the system. The second approach focuses on separating and recovering the greenhouse gases exhausted from the system. Currently, four GHG recovery systems, based on different separation techniques, are operational at the LHC experiments, each targeting different greenhouse gases. Finally, the third strategy involves the search for new eco-friendly gas mixtures that allow the detectors to operate with suitable performance in both the short and long term. This contribution details the implementation of these three strategies and presents the results achieved to date, with a focus on future developments and perspectives.