Dr Meysam Qadrdan is currently a lecturer in Energy Networks and Systems at Cardiff University, UK, after being a research associate for three years at Imperial College London, UK, and at Cardiff University. His research focuses on the operation and expansion planning of integrated gas and electricity supply infrastructure and large-scale optimisation models for multi-vector energy systems. He has been involved in a number of energy-modelling research projects in close collaboration with leading UK universities, industry and government departments. Dr Qadrdan has published more than 20 papers in journals and conference proceedings. Dr Muditha Abeyesekera is a research associate at the Institute of Energy, Cardiff University, UK. His research investigates the future pathways to decarbonise energy supply, gas-network modelling with alternative fuels and the analysis of integrated multi-energy systems. Muditha holds a dual Masters degree in Energy Engineering from the KTH Royal Institute of Technology, Sweden and Polytechnic University of Catalonia (UPC), Spain and a PhD from Cardiff University. Prof. Jianzhong Wu joined Cardiff University, UK in June 2008 (lecturer 2008; senior lecturer 2013; reader 2014; professor 2015). From 2006 to 2008, he was a research fellow at the University of Manchester, Manchester, UK. He received his PhD in 2004 from Tianjin University, China and then worked there from 2004 to 2006. His final position there was as an associate professor. Prof. Wu researches on smart grid and energy infrastructure (modelling, analysis and design of integrated smart energy supply networks, i.e. integrated         electricity/gas/heating/cooling/hydrogen networks). He has contributed to a number of EU and UK funded projects as a principal investigator or a co- investigator. He is a co-author of the book “Smart Grid: Technology and Applications” (2012, Wiley). Prof. Nick Jenkins is the head of the Institute of Energy at Cardiff University, UK. From 1992 to 2008, Nick Jenkins was at the University of Manchester Institute of Science and Technology (UMIST), Manchester, UK. In March 2008, he moved to Cardiff University where he is now a professor of Renewable Energy. His previous career included 14 years of industrial experience, of which 5 years were in developing countries. His final position in industry was as the project director for the Wind Energy Group, a manufacturer of large wind turbines. He has developed teaching and research activities in both electrical power engineering and renewable energy. He is a fellow of the Institution of Engineering and Technology (IET), The Institute of Electrical and Electronics Engineers (IEEE) and Royal Academy of Engineering. From 2009 to 2011 he was the Shimizu Visiting Professor to the Atmosphere and Energy Program at Stanford University, USA. ;Ms Bethan Winter is the system operation manager at Wales & West Utilities. Bethan started her career in 1997 at Transco (later National Grid) and had roles in both Gas Distribution and Gas Transmission before moving to Wales & West Utilities in 2009. She currently manages System Operation, which includes 24/7 monitoring and control of the South West England and Wales Networks, greater than 7 bar Planning, Gas Quality and Gas Network Exit and Entry. Her contribution to this publication focusses on gas-network operation and supply and demand balancing.