Considering RQ1, use cases of interest have been identified as visualized in Fig. 2. The use cases are clustered into three subgroups presented successively in the following.
The first subgroup is P2P electricity trading. A central trusted third party (TTP) contradicts the idea of P2P trading and obviously storing state is necessary for being able to trade. In addition, a trading partner might be unknown and therefore possibly untrusted. This is the area in which most research and development is done at the moment and in which recent studies see a high potential, mainly because local trade is currently not possible due to the complexity in current electricity trading processes. Specifying, the use cases of interest are electricity trading on different levels, each with different requirements. The most investigated use case at the moment is LEMs (or communities), in which P2P trading (or sharing) is facilitated between end consumers or producers in a locally limited area. The same concept is also applicable on other levels, from device level up to distribution system operator (DSO) or transmission system operator (TSO) level. Besides trading the electricity, trading of certificates of origin or CO2 emissions is also possible. This is mainly motivated by the properties of blockchains considering transparency and immutability.
The second subgroup is the provision of flexibility as an ancillary service for the EPS. In comparison to the market-based approaches summarized under P2P electricity trading, this approach faces the need for flexibility in the EPS in a more straightforward way. So far, such flexibility is either provided by central power plants, which will become less in numbers in future, or by centrally controlled VPPs. A new blockchain-based approach for such services is a decentralized virtual power plant (DVPP), which is a self-organized VPP and thus without the need for a central operator. This way there are no costs for an always-online TTP and the participants can profit from the full economic benefit. The DVPP has thus the potential of organizing and mobilizing small-scale distributed flexibility sources, which are not part of a VPP and do not have access to a flexibility market so far. In analogy to a VPP, possible applications are frequency or voltage stability or congestion management. Such a DVPP is currently implemented in our lab and a pre-stage of is published in (Schlund et al., 2018b).
The last identified subgroup is battery electric vehicle (BEV) charging. This is chosen as it is expected that the share of BEVs will increase drastically in the next years and because uncoordinated charging might cause problems in distribution grids. A TTP is undesirable as there are many different charging station operators and energy providers involved. As of today, problems already exists considering the interoperability between different providers.