Multicarrier energy systems

In recent years, the power system studies changed dramatically, shifting their focus from power system expansion planning as well as operation quality enhancement to other issues such as the integration of large amounts of renewable resources, the definition of new roles for the Transmission System Operator and Distribution System Operator since more and more generation is moving on the distribution side, resiliency of grids and economic sustainability of the on-going revolution in the energy field. Most energy infrastructures in the world were developed in the second half of the 20th century. The main question in energy system planning and development is whether these old systems can meet future growing needs for different types of energy carriers or not. Along with composite energy transfer systems, many of the installed equipment and tools are getting close to their useful lifetime or their relevant operational limitations. In addition, challenges such as the continuous growth of energy demand, still a strong dependence on fossil fuels, the need for power system reinforcement and the deep penetration of clean and sustainable energy resources raise the need for a new vision of energy systems along with some basic changes in existing systems. Adopting the distributed generation units as well as gas-fired power generation technologies such as combined heat and power units or combined cooling, heat and power units, gas furnaces, gas converters, etc., in an energy hub has motivated applied research to investigate how to integrate different infrastructures such as electricity, natural gas and heat. The resulting system, called multienergy carriers, hybrid systems or combined energy systems, requires the application of new and integrated modelling as well as operation tools. Possible scenarios for the future of the energy systems have been developed to overcome limitations of current structure due to a stronger interaction among different infrastructures (for example, gas and electricity). Many studies were oriented to guarantee standard levels of voltage and frequency in electrical systems or standard gas pressure in pipes in presence of increasing gas and electrical loads. Although these studies provided important details for the systems under investigation, they often propose solutions in line with existing reality and limit the analysis in finding an optimisation of the existing system without considering the possibilities deriving from different architectures. Modern energy systems, nowadays, must consider the coexistence of multiple carriers of energy, and, in the future, the concurrent planning and operational optimisation of them can provide an effective approach for improving economical performances, increasing sustainability and ensuring a secure and resilient operation. This chapter will present some modelling and optimisation issues of strongly interacting energy systems and explore the possibility offered by multicarrier energy systems to improve the overall efficiency of coupled systems.