1. Whole System Approach to Energy 2. Interactions Across Electricity and Gas Networks 3. Power-to-Gas (P2G) Concept 4. P2G Design and Mechanism of Work 5. P2G in Integrated Markets of Gas and Electricity 6. P2G planning in the integrated Gas-Electricity Networks 7. Integration of P2G Technologies in Operation of integrated Gas-Electricity Networks 8. P2G integration in the Distribution Grids of Gas and Electricity 9. Flexibility Modelling of P2G 10. Environmental assesment of P2G 11. Multi-objective applications of P2Gs 12. The role of P2G technologies in hydrogen/ electric-based refueling station 13. Economic evaluation of P2G in gas-electricity-based virtual plants 14. P2G application in decreasing constraint payment caused by renewables 15. P2G backup services for gas-fired CHP units