Biogenic renewable gas injection into natural gas grids: A review of technical and economic modelling studies

Abstract

Biogenic renewable gas, which includes biomethane from anaerobic digestion, and biomass-derived synthetic natural gas (bioSNG), can play a role to help decarbonise future energy systems and meet renewable energy targets One way in which renewable gas can offset fossil use is by injecting it into natural gas networks. This work reviews 23 peer-reviewed journal papers that outline the state-of-the-art in technical and economic assessments of biogenic renewable gas injection. The review has particular focus on (i) the technical constraints gas grids place on biogenic renewable gas injection, (ii) models for biogenic gas production and supply chains, (iii) the use of compressed natural gas (CNG) as a vehicle fuel, (iv) the optimisation of injection facility location, and (v) the incorporation of SCADA data recorded by gas network operators. The review found that the state-of-the-art literature highlighted the importance of models that analyse the production, injection, and distribution of biogenic renewable gas in the gas grid. Research to date has developed models to optimise biogenic renewable gas supply chains and injection points. These optimisation models have been approached from several different perspectives, including (a) maximising renewable gas production, (b) minimising the cost of energy, and (c) matching the variable nature of gas demand. Models have also been created to determine the impacts of biogenic renewable gas injection on gas networks. These models have been used to assess gas blending in the network, including pressures, Wobbe index (WI), higher heating value and gas composition. However, it also identified several gaps in the literature that should be addressed in future work. Firstly, the state of the art does not include a comprehensive study where all the potential impact factors associated with biogenic renewable gas injection are considered. Secondly, studies that model and optimise the locations for renewable gas injection facilities have not given consideration as to how the injected gas will affect gas flow within the network. Finally, the impact of CNG demand on gas networks and their capacity to accept renewable gas injection should be determined.