Electro Compression a Challenging Alternative: How and Why to Choose a Gas Turbine or an Electric Motor to Drive a Centrifugal Compressor

Abstract

In the past decade, electric motors have become a challenging alternative to gas turbines to drive centrifugal compressors [1] [7], mainly because of the progress of Variable Frequency Drives main components allowing to drive high power motors. Low Electricity prices (mainly in France) and environmental concerns have contributed to spread that technology across Europe. As flexibility needs and environmental constraints will grow in the gas transmission business, the option to drive the centrifugal compressors with an electric motor will be taken into consideration more and more often either for technical, regulatory or economic reasons in future compressor station projects [2]. GRTgaz, the main gas transmission company in France, decided in the early 2000’s to enlarge and renew its compressor fleet (42 units to be installed between 2004 and 2014 in a 5 to 14 MW power range). GRTgaz is taking that option into account for each of these projects considering the following criteria, related to 3 main considerations: Operational needs: • Availability, reliability • Rangeability needs • Flexibility needs • Type of compressor station (head, peak, network core) • Access to the electrical grid • Available space for the site • … Environmental constraints: • Environmental Footprint • Air emissions • Noise • … The full possession cost for a 30-year period: • Investment cost • Energy cost • Maintenance cost • CO2 quota prices This paper is proposing to develop how these criteria are assessed, what hypotheses are made to help the decision and to share GRTgaz feedback on the projects that have already been completed. Some examples will be presented.