GENEVA — The European Organization for Nuclear Research has unveiled an ambitious environmental roadmap targeting a 50 percent reduction in direct carbon emissions by 2030 even as the Large Hadron Collider ramps up to unprecedented data production levels, according to the organization's fourth Environment Report released in November.

The report, covering activities in 2023 and 2024, demonstrates that CERN is balancing cutting-edge physics research with environmental responsibility through technological innovation, operational optimization and strategic planning for future facilities including the High-Luminosity LHC scheduled to begin operations in 2030.

Record Physics Output Achieved With Greater Efficiency

CERN achieved a significant milestone during the reporting period when the LHC delivered its highest-ever integrated luminosity, a measure of the total number of particle collisions produced over time. This record output was accomplished while improving the energy efficiency of the accelerator complex when measured by data delivered per unit of energy consumed.

The achievement underscores a central theme of environmental strategy at major research facilities: doing more science with less environmental impact. The efficiency gains result from years of technological improvements, operational refinements and systematic efforts to optimize every aspect of accelerator performance.

Benoît Delille, head of CERN's Occupational Health and Safety and Environmental Protection Unit, emphasized the dual mandate facing modern scientific institutions. Science should not just address global challenges but should act locally, he said. CERN's scientific goals go hand in hand with its commitment to respecting the planet.

Comprehensive 2030 Environmental Objectives Approved

In 2024, CERN's Enlarged Directorate approved an updated framework of environmental objectives spanning nine key domains through 2030: energy, greenhouse gas emissions, water, biodiversity, non-hazardous waste, radioactive waste, ionizing radiation, noise and hazardous substances.

The centerpiece commitment involves limiting electricity consumption to 1.5 terawatt-hours per year during Run 4 of the Large Hadron Collider despite a significant increase in physics output. This target represents a careful balance between scientific ambition and environmental constraint, requiring continued efficiency improvements across all systems.

The 50 percent reduction in direct carbon dioxide-equivalent emissions compared to 2018 levels will be supported primarily by cutting gas consumption by 60 percent. This aggressive emissions reduction target focuses on fluorinated gases used in detector systems, which account for approximately 78 percent of CERN's direct emissions.

Water management forms another critical component of the 2030 objectives. CERN aims to improve effluent water quality, increase on-site water retention capacity and limit overall water consumption while meeting growing demands for cooling water as computing needs expand and the climate warms.

Biodiversity enhancement on CERN sites represents a newer dimension of environmental commitment. Objectives include strengthening local ecosystems and addressing urban heat island effects, where developed areas experience significantly higher temperatures than surrounding rural regions, particularly at night. This work connects scientific operations with broader ecological restoration efforts.

The organization also commits to strengthening waste management and noise control actions, recognizing that research facilities must be responsible neighbors to surrounding communities.

Fluorinated Gases Remain Primary Emissions Challenge

The large experiments at the LHC use various gas mixtures for particle detection and detector cooling, including fluorinated gases with high global warming potential. These F-gases, encompassing hydrofluorocarbons, perfluorocarbons and sulfur hexafluoride, have proven essential for detector operations but carry significant environmental costs.

CERN has developed a multi-pronged strategy to address F-gas emissions through gas recuperation, optimizing current technologies, and replacing gases with more environmentally friendly alternatives. During LHC Run 2, researchers successfully tested a prototype recuperation plant for HFC-134a, one of the primary refrigerants, achieving recovery efficiency approaching 80 percent on real detectors.

The organization has also pioneered the replacement of F-gases with carbon dioxide in cooling systems for silicon detectors. Although CO2 presents technical challenges, including the need for different infrastructure and temperature management, its global warming potential registers thousands of times lower than F-gases.

These gas management efforts will intensify during Long Shutdown 3, scheduled to begin mid-2026. This extended maintenance period provides crucial opportunities to repair leaks, upgrade gas systems and implement new recovery technologies before Run 4 commences.

Energy-Efficient Data Center Sets New Standards

Among concrete achievements during 2023-2024, CERN inaugurated a highly energy-efficient data center with a target power usage effectiveness of 1.1, significantly better than the global average of approximately 1.5 for large data centers. The PUE metric compares total facility energy consumption to the energy used specifically for computing, with values closer to 1.0 indicating superior efficiency.

The new data center incorporates a heat recovery system designed to capture waste heat and redirect it to warm 73 buildings on CERN's Prévessin site. This closed-loop approach transforms what would be wasted energy into useful heating capacity, demonstrating how research facilities can integrate sustainability into infrastructure planning.

Heat recovery extends beyond the new data center. CERN has established partnerships with neighboring communities to provide district heating using waste heat from accelerator cooling systems. One project supplies heating for up to 8,000 residents in Ferney-Voltaire, France, while studies explore similar opportunities for other areas.

The organization also achieved ISO 50001 certification for energy management during the reporting period. This international standard provides a framework for establishing systems and processes to improve energy performance, including energy efficiency, use and consumption.

High-Luminosity LHC Embodies Sustainable Physics Vision

The High-Luminosity LHC represents CERN's major upgrade project for the next decade and exemplifies how environmental considerations increasingly shape research infrastructure planning. Scheduled to begin operations in 2030, the HL-LHC will deliver ten times the integrated luminosity of the current LHC, dramatically expanding discovery potential for rare processes and subtle effects.

Achieving this tenfold increase while meeting the electricity consumption target of 1.5 TWh per year during Run 4 requires substantial technological innovation. The HL-LHC will incorporate advanced superconducting technologies, two-quadrant power converters that improve energy recovery, and numerous other efficiency enhancements developed specifically for sustainable high-energy physics.

The upgraded facility will produce at least 15 million Higgs bosons per year compared to approximately three million during 2017 LHC operations. This massive increase in physics output per unit of energy consumed demonstrates that fundamental research can continue expanding its frontiers while shrinking its environmental footprint through intelligent engineering.

Environmental considerations now permeate planning for CERN's next flagship project, currently in conceptual development stages. Limiting environmental impact and harnessing technologies for society serve as key priorities alongside scientific objectives, marking a cultural shift in how major research organizations approach long-term planning.

Electricity Consumption Patterns Reflect Operational Cycles

CERN's electricity consumption fluctuates dramatically based on accelerator operational status. During years with full operations, consumption reaches approximately 1.2 TWh, with the LHC accounting for roughly 55 percent of total use. The organization procures electricity primarily from France, where the generation mix remains approximately 90 percent low-carbon, predominantly from nuclear power.

This low-carbon electricity supply helps keep CERN's scope 2 emissions, those associated with purchased electricity, relatively modest compared to direct operational emissions. However, the organization recognizes the importance of limiting overall consumption growth regardless of the electricity source's carbon intensity.

Long shutdowns provide revealing contrasts in energy use. During the 2019-2020 shutdown period, electricity consumption dropped approximately 64 percent compared to operational periods, demonstrating the massive energy requirements of particle physics research while also highlighting opportunities for efficiency improvements during active runs.

Peak power demand with the full accelerator chain running reaches about 180 megawatts, equivalent to roughly half the capacity of the nearby Génissiat hydroelectric power plant in France. This substantial demand underscores why research facilities constitute significant stakeholders in regional energy planning and why efficiency improvements deliver meaningful environmental benefits.

Computing Needs Present Growing Sustainability Challenge

The worldwide LHC computing grid represents one of the planet's largest computing infrastructures, processing and storing the vast quantities of data generated by particle collisions. By the time HL-LHC begins operations, total computing capacity requirements are expected to grow by up to a factor of ten compared to current needs.

Meeting these computing demands sustainably requires multiple approaches. CERN focuses on modernizing code, developing software that runs more efficiently on latest-generation hardware, and improving data management to reduce unnecessary duplication and processing. Machine learning and related technologies increasingly provide pathways to reduce overall computing resource requirements while maintaining or improving analytical capabilities.

The efficiency gains from the new data center will prove essential, but computing sustainability extends beyond CERN's facilities. The worldwide LHC computing grid encompasses hundreds of institutions globally, and comprehensive sustainability requires coordination across this distributed infrastructure.

Energy consumption by data centers worldwide reached approximately 1.5 percent of global electricity use in 2024, with projections indicating this could more than double by 2030 according to International Energy Agency forecasts. Research computing represents a significant subset of this growing demand, making efficiency improvements at facilities like CERN's new data center increasingly important as computational science expands.

Scope 3 Emissions Present Measurement Challenges

CERN has increasingly focused on understanding and managing scope 3 emissions, which arise from activities outside direct operational control, including business travel, personnel commutes, catering, waste treatment, water purification and procurement.

Personnel commutes and long-distance flights for business travel constitute the bulk of measured scope 3 emissions. The organization aims to keep individual motorized vehicle commuting constant through 2025 despite a growing scientific community, encouraging public transportation, cycling and carpooling while improving infrastructure for sustainable commuting options.

Procurement presents the most complex scope 3 challenge. Given CERN's specialized equipment needs, diverse supplier base and procurement policies designed to balance return to all member and associate member states, accurately quantifying procurement-related emissions requires sophisticated methodologies still under development.

The COVID-19 pandemic provided unexpected insights into scope 3 emissions flexibility. Remote collaboration tools enabled continuity of some scientific work while dramatically reducing travel-related emissions, suggesting opportunities for more sustainable operations even as in-person collaboration resumes.

Water Management Balances Competing Demands

Water use at CERN primarily involves cooling systems essential for superconducting magnets, detectors, computing facilities and other infrastructure. The organization draws water from several sources, including the Rhône River and Lake Geneva, and maintains extensive monitoring to ensure effluent water meets quality standards before release.

Climate change adds complexity to water management planning. Rising temperatures increase cooling demands while potentially affecting water availability and temperature in source water bodies. These competing pressures necessitate improved water efficiency, enhanced retention capacity and proactive planning for future scenarios.

CERN has constructed retention basins to protect local watercourses from accidental pollution and mitigate consequences of extremely heavy rainfall. These infrastructure investments reflect recognition that environmental protection requires both operational improvements and physical systems capable of preventing incidents.

Water quality monitoring extends beyond regulatory compliance to encompass broader ecological responsibility. CERN maintains 146 state-of-the-art environmental monitoring stations tracking various parameters in water, air and soil to ensure operations remain within safe limits and identify opportunities for continuous improvement.

Biodiversity Initiatives Connect Science With Nature

CERN sites host diverse flora and fauna, and the organization increasingly recognizes ecological stewardship as integral to environmental responsibility. Biodiversity objectives for 2030 emphasize enhancing local ecosystems rather than merely avoiding harm.

Initiatives include habitat creation and restoration, native species planting, and innovative applications of technology developed for particle physics. For example, CERN has adapted AI-powered sensors originally designed for particle detection to monitor birdsong and biodiversity, demonstrating how scientific tools can serve multiple purposes.

Addressing urban heat islands represents another dimension of biodiversity work. By incorporating green infrastructure, managing surface materials and implementing other cooling strategies, CERN aims to create more hospitable microclimates that benefit both ecosystems and human communities.

These efforts position CERN as more than a user of land resources. By actively managing sites to increase ecological value, the organization contributes to regional biodiversity conservation while fulfilling responsibilities to surrounding communities.

Progress Tracking Through ESG Framework

CERN has committed to transitioning toward broader environmental, social and governance reporting frameworks that encompass sustainability dimensions beyond traditional environmental metrics. This evolution reflects growing recognition that research organizations operate within complex social and economic systems and bear responsibilities extending beyond immediate operational impacts.

The organization publishes environment reports biennially, with each iteration building on previous efforts while incorporating new objectives, methodologies and reporting standards. This regular cadence enables tracking progress over time and maintaining accountability to member states, staff, neighboring communities and the broader public.

The fourth Environment Report represents the culmination of years developing robust monitoring systems, establishing baseline measurements, setting ambitious targets and implementing concrete actions. Future reports will track progress toward 2030 objectives while potentially expanding scope to address emerging sustainability challenges.

Global Research Community Eyes CERN Model

As one of the world's premier research institutions, CERN's environmental commitments carry significance beyond the organization itself. The approaches developed at CERN provide models for other large-scale research facilities grappling with similar tensions between expanding scientific ambitions and environmental constraints.

The Energy for Sustainable Science at Research Infrastructures workshops, established in 2011, enable research organizations worldwide to share best practices in energy management. CERN regularly presents innovations such as magnet power supply reorganization, heat recovery systems and gas recuperation technologies that other facilities can adapt to their specific contexts.

Superconducting technologies developed for particle physics applications increasingly find uses addressing global challenges in healthcare, transportation, energy systems and other domains. CERN's work advancing next-generation high-temperature superconductors promises improved energy efficiency and sustainability across multiple sectors.

This knowledge transfer demonstrates how investments in fundamental research generate broader societal value while improving the sustainability of science itself.

Implementation Challenges Require Sustained Commitment

Despite comprehensive planning and concrete achievements, meeting 2030 objectives will require sustained effort across all organizational levels. The complexity of operating unique research infrastructure while implementing major upgrades creates numerous technical and logistical challenges.

Budgetary constraints necessitate careful prioritization of environmental investments alongside scientific priorities. While environmental objectives receive strong institutional support, implementation depends on securing adequate resources in competitive budget environments where multiple legitimate demands require resolution.

Long Shutdown 3 represents a critical inflection point. The extended maintenance period beginning mid-2026 offers opportunities to complete major emission reduction projects, but delays or complications could impact the achievability of 2030 targets.

The transition to HL-LHC operations introduces additional variables. While designed with efficiency in mind, the upgraded facility's actual performance will determine whether electricity consumption remains within targeted limits while delivering promised scientific output.

Sustainable Discovery

CERN's fourth Environment Report portrays an organization seriously engaged with environmental challenges while pursuing its fundamental scientific mission. The commitment to cutting emissions by 50 percent while dramatically increasing physics output represents an ambitious bet that technological innovation can reconcile these seemingly competing objectives.

Success will require continued engineering advances, operational refinements, cultural commitment to sustainability throughout the organization and adaptation to unforeseen challenges. The stakes extend beyond CERN's immediate footprint to encompass the organization's role as a model for sustainable large-scale research globally.

The report emphasizes that protecting the planet remains inseparable from pushing back frontiers of knowledge. As humanity confronts climate change and other environmental crises, demonstrating that world-class science can operate sustainably becomes increasingly important.

CERN aspires to prove that the pursuit of fundamental understanding need not come at the planet's expense, and that environmental responsibility strengthens rather than constrains scientific excellence. The journey toward 2030 will test whether this vision can be fully realized at the cutting edge of human knowledge.