Changes to regulations for the limitation of emissions frequently create a challenge for the future operation of existing equipment which uses combustion processes for performing its duties. This is particularly true for mature installations using machinery designed without even an idea of the regulations applicable today or tomorrow. This presentation covers important aspects regarding the application of emissions limitations to existing installations in natural gas transport pipeline systems, namely gas turbines (GT) driving natural gas compressors. A method to evaluate the optimum solution for individual installations will be highlighted. The requirements resulting from the related EU directive will be named. The degree of fulfilment of these requirements by mature GT models will be shown by examples, pointing out the need to apply changes to the installation. Subsequently, the main technical measures which have been identified as suitable in principle to implement the change will be presented: - Modify GT combustion system - Exchange GT with a suitable GT model - Exchange GT with an electric drive - Exchange compressor set - Apply exhaust gas treatment A way ahead will be illustrated for selecting the best alternative based on a techno - commercial evaluation in the frame of a feasibility study.