Biomethane injection: feedback from urban wastewater treatment plants (WWTPs)

This document is a technical guide about the injection of biomethane produced from urban wastewater treatment plant (WWTP) sludge. Its aim is to support industry players in all aspects of project development and site operation. It is based on 10 years' experience gained from 35 project managers of WWTP methanization units. The lessons learned are used to describe the wide range of economic, regulatory and environmental issues facing project developers. This technical guide is a valuable tool for the development of these facilities, in support of the ecological transformation of regions. It provides a detailed overview of the lessons learned on methanization at urban wastewater treatment plants for injection into the gas distribution system, and focuses on several major aspects: regulatory framework applied to installations, design choices and technical operation, performance and operating incidents, common contractual structures, financing, prospects for site optimization and innovation. In so doing, it underlines the satisfactory performance of biogas purification and injection equipments, as well as the expected development opportunities and technological advances. In January 2024, 47 WWTPs were injecting biomethane into the gas distribution network, a fivefold increase with respect to 2018. This represents 565 GWh/year of installed capacity, equivalent to the space heating and domestic hot water consumption of more than 77400 homes or the fuel consumption of 2260 buses running on BioNGV. Biomethane injection capacity could double by 2030, reaching an additional 1 TWh thanks to the mobilizable potential of about a hundred wastewater treatment plants