Spanning two nations, the Future Circular Collider (FCC) presents a unique challenge – one that also unlocks a hidden opportunity. While navigating the complexities of international collaboration in construction and administration, the FCC will become a breeding ground for innovation across the entire project.

These advancements, fostered by the project's international scope, have the potential to dramatically reduce the environmental impact and construction costs not only for the FCC itself, but also for numerous future construction endeavours across Europe and beyond.

France and Switzerland, the two CERN host-states require credible and demonstrated pathways for managing the excavated materials that the FCC construction will generate. 95% of the materials are expected to be so-called "molasse", a soft and heterogeneous sedimentary rock typical of the Lemanic basin. Working out how this material can be used as a resource instead of being disposed of as waste is of outmost importance. Today, no industrial scale application scenario exists for this type of material.

In 2021-2022, the FCC Innovation Study, a Horizon 2020 project co-funded by the European Union and led by CERN, carried out an international challenge-based competition called “Mining the Future” to invite scientists and companies worldwide to propose technically feasible approaches for the use of molasse that are demonstrated today at laboratory scale and which could be brought to product level maturity by 2030. The result was the identification of an integrated approach that combines local and innovative schemes to be able to manage significant amounts of molasse materials in the FCC construction project.

One part concerns the online identification, sorting and pre-treatment of the materials during the excavation process. The other part deals with the preparation of different re-use pathways of the sorted and pre-treated materials. They include the transformation of the sterile rock into fertile soil for agriculture, forestry and renaturation applications. Other re-use pathways are the compacting of the materials for use as construction materials on-site.

The quality-assured creation of fertile soil is a lengthy, multi-year process and has therefore been chosen as the first large-scale demonstration with field tests at an “open sky laboratory” under controlled conditions. The process exploits “agro-ecology” to enhance climate resilience, restore natural systems, re-gain land, analyse the carbon sequestration potentials and improve the agriculture and forest sector resilience. For the installation of the so-called "OpenSkyLab", a plot of about 10'000 m2 located near LHC point 5 (CMS, Cessy, France), has been made available and will be prepared in collaboration with the SCE and other departments (EN-CV for the water supply, EN-EL for the electrical connection and IT for the fiber connection). Molasse originally extracted during the HL-LHC excavations will be transported back to this field to be used in the tests. Initial laboratory analysis will be performed off-site to identify the most suitable mix of molasse and amendments. These will be followed by field tests in a controlled environment (monitoring of the field, weather and plant growth conditions). using scientific protocols developed by a collaboration of universities who work in this domain.

In line with CERN’s long-standing tradition, this project relies on an open collaboration with academia and industry. Currently the collaboration includes university experts in agronomy, pedogenesis and geology (HEPIA, BOKU, BRGM, Montan University Leoben), industrial partners in soil engineering and phytoremediation (Microhumus, Edaphos), soil treatment techniques (WSP-BG, MS) and in monitoring and supervisory control systems (BECC).

A socio-economic assessment of the reuse cases for the transformed soil will be performed to evaluate the economic benefits and cost reduction potentials for the FCC construction and the potential benefits for the entire construction sector in Europe.

Acceptability and cost efficiency of the FCC project are linked to the demonstration of excavated materials re-use potentials. OpenSkyLab targets the demonstration of innovative and credible processes for the reuse of molasse for renaturation, agriculture and forestry in line with the principles of circular economy.