The Energy Hub – A Powerful Concept for Future Energy Systems

Introduction Many of today's energy infrastructures evolved during the second half of the twentieth century and it could be questioned if they meet the requirements of tomorrow. Besides congested transmission systems, many facilities are approaching the end of their prospected life time. In addition to that, other issues such as the continuously growing demand for energy, the dependency on limited fossil energy resources, the restructuring of power industries, and the general aim of utilizing more sustainable and environmentally friendly energy sources raise the question whether piecewise changes of the existing systems are sufficient to cope with all these challenges or a more radical change in system design be needed. Various scientific studies have investigated future scenarios based on boundary conditions given by today’s structures, such as standardized electric voltage and gas pressure levels. Although these studies provide important insights, they often result in solutions that comply with the existing systems; possibly interesting and more long-term oriented solutions are “hidden”, as they lie beyond system-given boundaries. In contrast to these studies, a project named Vision of Future Energy Networks was initiated at ETH Zurich together with partners that aims at a greenfield approach for future energy supply systems. Restrictions given by the existing systems are basically neglected in order to determine “real” optima. The consideration of multiple energy carriers, not only electricity, represents one of the key characteristic of this project. It is believed that synergies among various forms of energy represent a great opportunity for system improvements. Besides the possibilities of modern information technology, state-of-the-art as well as emerging and looming energy technologies, e.g. fuel cells, are taken into account. The time horizon for implementation is set to 30 to 50 years from now. Thus, the basic question to be answered is: “How should energy systems look like in 30 to 50 years, and what can be expected from them?” Under these conditions, two key approaches are reasonable: transformation, conversion, and storage of various forms of energy in centralized units called energy hubs, and combined transportation of different energy carriers over longer distances in single transmission devices named energy interconnectors. It was soon realized that only a few established tools are available for the integrated analysis of multiple energy carrier systems, thus the project focused in a first phase on developing a modelling and analysis framework. In the second phase, which recently started, optimal system structures and operation strategies are determined and compared with conventional infrastructures using the developed tools. The result of this phase is the greenfield approach. The final phase of the project is dedicated to identifying transition paths and bridging systems leading from today’s systems to the identified optimal structures. Figure 1 outlines this process.