Continuous Measurement of Methane Emissions from Turbines and Compressors Using Predictive Emissions Monitoring (PEMS) Technology – New Insights from a Global Deployment Programme

Abstract A new predictive emissions monitoring system (PEMS) is presented for the continuous measurement of methane emissions from incomplete combustion in natural gas-fuelled turbines and engines used in oil and gas production facilities. The method integrates condition monitoring and environmental data with first-principles models of energy and mass conservation to derive continuous tracking of methane emissions with minute-level resolution, full traceability, and an estimation of uncertainty. It is designed to fulfil the expectations of site-specific methane emissions reporting, including Level 4 of the Oil 1 to 1,000 ppm, including lower than background concentrations. These trends in emissions are far more complex than historic emission factors derived from population-based sampling and fuel use would imply. When operated under optimal load, very low levels of methane slip can be achieved, but the situation can reverse under low-load conditions. Rapid changes in emissions during start-up and shut-down sequences are observed that need to be accounted for when conducting site-level reconciliation of emissions (to meet requirements such as OGMP 2.0 Level 5), or comparing reported emissions to third-party measurements. However, these short-lived events do not substantially change total emissions over extended periods of operation. By utilizing existing condition-monitoring data and digital connectivity, PEMS provides a rapid and accessible solution and relay of information to the operator. If this potentially significant source of methane emissions is to be accurately monitored and reduced, then continuous tracking provides the basis for targeted and defensible interventions. Guidance on the effective use of equipment is critical to emissions management, which must be conducted while taking into consideration CO2 and other environmental risks, such as NOx. Combining this data can reduce and potentially eliminate methane slip from stationary combustion.