Multi-energy systems (MES) couple various energy sectors and networks such as electricity, gas, heating, cooling, transport, water, waste, etc. to unlock energy flexibility and provisions for cost-effective operation while realizing low-carbon smart electricity grids. These systems are the key for generating new types of energy flexibility as well as techno-economic and environmental opportunities for the future complex energy system. This issue is discussed in Technical Brochure (TB) 863 which was produced by JWG C6/C1.33. The Australian members of this working group were Alex Baitch and Kerim Mekki.
The scope of this work was to study configurations, impacts and prospects of MES that enable enhanced solutions for intelligent electricity systems, energy storage and demand side management in electricity grids with an increasing share of distributed energy resources. The work identifies the benefits of MES, such as:
Initially, the JWG created a common definition of MES seen from a distribution grid perspective and which represented the varied viewpoints and interests of a wide variety of stakeholders. The JWG documented prevailing architecture, regulatory frameworks, and the perspectives of operation, planning and design of MES to explore their impact on electricity distribution systems. Planning, control, and operation require system modelling and tools and the JWG identified state-of-the-art candidates that are able to describe the MES and networks from a single building through to a region or nation-state. Examples from 13 countries representing 5 continents are provided, showcasing the emerging relevance and applicability of the work.
The JWG identified existing practices, use in different scenarios, and case studies of known active MES. These known systems permitted the JWG to fully define a collection of barriers, whether techno-economic, market, or regulatory in nature, as well as solutions for adopting MES in practice as guidance for future implementation. An overall structure and energy flow in a MES is illustrated in Figure 1.
Figure 1 - Structure of MES incorporating renewable energy, gas and active distribution grids with connection to district heating and local district cooling (European Technology and Innovation Platform, ETIP-SNET, “Sector Coupling: Concepts, State-of-the-art and Perspectives,” M. Münster et al, Jan 2020)
In this picture, the different energy vectors are connected via energy conversion units, making the system rather complex because of the many cross-connections among the different energy carriers. Therefore, there is a need for a deep understanding of these interrelations, the regulations and the involvement of key stakeholders to make such a system work. This is the main focus of the TB.
Figure 2 shows an example of a high-level conceptual architecture for operating a MES. Many different stakeholders and markets will have to be involved to operate a MES in the future.
The Working Group made the following observations:
There is an extensive bibliography of texts which have been referenced in the TB.