This work showcases the relevance of how integrated modelling allows engineers to begin describing the behaviour of future energy systems and consequently help stakeholders make informed decisions on complex issues. It is important to clarify that no single entity in today's energy sector - private or state enterprise - has complete control of the energy exchanges between infrastructures and technologies that are modelled here. As a consequence, the optimisation tool featured in this text implicitly assumes that it has the authority and capability of effectively coordinating all the elements within the urban energy system. For that reason, the results from the simulations serve only as a benchmark to determine what techno-economical improvements are possible in relation to today's energy flows. But most importantly of all, it simultaneously addresses the relevance and value of having a central coordinating body in an environment that no longer resembles traditional power systems.

To address the challenge of analysing the interactions between electrical and natural gas distribution networks, this work introduces an integrated power flow model where combined heat and power (CHP) units serve as a link between both infrastructures. However, conducting an integrated analysis of several energy networks is an elaborate task. This is because it requires at an early stage to model the basic components of each infrastructure through a steady-state load flow study. Power flow analysis is a valuable engineering tool and for long has been considered the cornerstone of high-hierarchy power system studies. By discussing load flow methodologies individually for each system, it is possible to build a generic framework to solve load flow problems in conjunction. Hence, this chapter focuses on laying the groundwork for analysing and synthesising electrical and natural gas networks. It is important for power systems engineers to acknowledge that some existing electric load flow techniques can be used to solve natural gas load flow problems. Also, it is key that each load flow process is comprehended, making it later feasible to simultaneously assess both electrical and natural gas networks. Although, as expected, some special considerations must be taken to conduct an integrated electrical and natural gas network analysis, these considerations include representing the natural gas system components and their respective fluid flow equations in a consistent manner with regard to their counterparts in electrical systems. By building analogies power system engineers can conveniently apply their knowledge on load flow studies directly into another key branch of energy systems, thus creating powerful modelling synergies which could eventually lead to exploring other infrastructures worth analysing (e.g. water and heat). In this chapter, basic principles and load flow models for electrical and natural gas systems are reviewed and they are based on References 18, 171-176. 3.1.

This chapter describes the optimisation program developed, referred to asTCOPF, by addressing the maths employed to set-up and calculate both the optimal dispatch of embedded technologies and the optimal power flow in electric and natural gas systems. Thus, allowing the TCOPF to act as a coordinating entity that manages costeffective interactions between embedded technologies and energy service networks.

This chapter details the principles applied to represent optimal charging of PHEVs by employing an agent-based model that simulates the travelling patterns of vehicles on a road network. The output data from the temporal and spatial movement of vehicles is used as a reliable forecast so the time-coordinated optimal power flow (TCOPF) program can devise optimal charging scenarios of PHEVs in a local electrical network. The effectiveness of the model is illustrated by presenting a multiday case study in an urban area. Results show a high level of detail and variability in PHEV charging when a present-day carbon fuel mix is compared to one with lower carbon intensity.