Measuring and monitoring emissions at data centers: A practical guide to compliance and performance

Measuring and monitoring emissions at data centers: Practical guidance for compliance and operational performance

Importance of the topic

Data centers are rapidly increasing their share of electricity consumption driven by AI, cloud services, and broader digitalization. This expansion frequently motivates on-site combustion-based power generation (natural gas turbines, reciprocating engines, and backup generators) to address interconnection delays and reliability needs. As facilities transition into partial or full power producers, emissions monitoring becomes essential for demonstrating regulatory compliance, ensuring community transparency, and supporting operational optimization and investor reporting.

Objectives and study overview

The white paper aims to provide a practical, technically grounded roadmap for emissions monitoring at data centers with on-site generation. It summarizes the regulatory context, contrasts monitoring approaches (periodic stack testing versus continuous emissions monitoring systems — CEMS), describes analyzer technology choices, and outlines design and operational considerations to achieve reliable compliance and useful operational insight.

Methods and monitoring approaches

• Stack testing: Periodic, EPA-method-based sampling at the stack is used for many smaller engines and emergency generators. Stack tests performed by accredited contractors are typically required at initial commissioning and at intervals defined by permits. Results can serve as primary compliance evidence where continuous monitoring is not mandated.
• Continuous emissions monitoring systems (CEMS): For larger turbines and engines or where permits require continuous data, CEMS provide near real-time pollutant measurements using a sampling train (sampling, conditioning) and analyzers linked to a data acquisition and handling system (DAHS). Common CEMS configurations include direct extractive, dilution extractive, and in-situ systems.
• Quality assurance: Even where CEMS are installed, periodic reference testing such as relative accuracy test audits (RATAs) and annual checks remain important to verify instrument accuracy and data integrity.

Instrumentation used

• Measurement principles: Chemiluminescence detection (CLD) is widely used for NOx measurement and is consistent with EPA Method 7E; non-dispersive infrared (NDIR) is commonly applied for CO in line with EPA Method 10. Oxygen (O2) measurements are often included for emissions correction and mass-basis reporting.
• Analyzer platforms: Modern, regulator-familiar analyzers offering built-in diagnostics, stable baselines, low detection limits, and field serviceability are recommended to reduce lifecycle costs and downtime. The white paper cites examples of analyzer families designed for continuous emissions monitoring and integrated DAHS compatibility.
• CEMS components: Typical systems combine sampling lines, particulate removal and moisture conditioning, analyzers, calibration gas systems, and a DAHS for automated reporting, alarms, and data archival.

Main results and discussion

• Regulatory fit: Facilities with on-site generation face layered federal, state, and local air quality requirements. Smaller backup sources often comply via periodic stack testing, while larger or continuously operating sources generally require CEMS for permit demonstration and continuous assurance.
• Operational benefits: Continuous monitoring not only supports compliance but also enables operational optimization—detecting combustion inefficiencies, guiding preventative maintenance, and identifying opportunities to reduce fuel consumption and emissions.
• Data integrity and lifecycle considerations: Selecting proven analyzers familiar to regulators, ensuring easy field servicing, performing routine maintenance, and integrating strong DAHS capabilities are key factors that determine long-term reliability and minimize compliance risk.
• Hybrid strategy: Many data centers benefit from a combined program where CEMS provides continuous oversight for major units and targeted stack testing validates performance, particularly after maintenance or fuel changes.

Benefits and practical applications

• Regulatory compliance: Implementing correctly specified monitoring systems supports permit conditions, reduces the risk of violations, and streamlines reporting to authorities.
• Operational resilience: Continuous emissions data provide near-real-time feedback to operations teams, improving the ability to respond to combustion upsets and maintain uptime.
• Environmental and stakeholder transparency: Reliable emissions data underpin corporate sustainability reporting, investor due diligence, and community engagement.
• Cost control: High-quality analyzers with remote diagnostics and field-serviceable designs lower total cost of ownership through reduced downtime and simpler maintenance cycles.

Future trends and applications

• Integration and automation: Expect deeper integration of CEMS with plant control systems and cloud-based DAHS for automated compliance reporting, predictive maintenance, and advanced analytics.
• Sensors and miniaturization: Advances in sensor technology and in-situ measurement methods may broaden options for lower-cost continuous monitoring on smaller units while maintaining regulatory-grade performance.
• Data transparency and reporting frameworks: Growing pressure from investors and customers will push data centers to provide standardized emissions disclosures and to use monitoring outputs in broader ESG programs.
• Policy evolution: As regulatory expectations evolve, facilities may face stricter thresholds, expanded pollutant lists, or more frequent validation requirements, increasing the need for robust monitoring strategies established early in project design.

Conclusion

Effective emissions monitoring is now a core requirement for data centers that operate on-site combustion sources. Early planning, selection of proven analyzer technologies, appropriate use of stack testing and CEMS, and rigorous data quality practices together form a defensible approach to compliance and operational excellence. Investing in serviceable analyzers, strong DAHS integration, and routine validation ensures long-term reliability while enabling operational insights that can reduce emissions and costs.

References

1. Shehabi A., Newkirk A., Smith S. J., Hubbard A., Lei N., Siddik M. A. B., Holecek B., Koomey J., Masanet E., Sartor D., et al. 2024 United States Data Center Energy Usage Report. DOI: 10.71468/P1WC7Q.
2. United States Environmental Protection Agency. Method 7E — Nitrogen Oxides (Instrumental Analyzer) (EPA emissions measurement guidance).
3. United States Environmental Protection Agency. Method 10 — Carbon Monoxide (Instrumental Analyzer) (EPA emissions measurement guidance).