## 7 Future Trends in Next-Generation Smart Grids (SGs) After the Integration of EV Market
### Rise of EV Market: Bi-Directional Charging and Newer Energy Trade Scenarios V2V, V2G, and G2V  
The number of EVs on the roads is increasing; for instance, 16.5 million EVs in 2021 were estimated to be on the roads, which is triple the amount in 2018 [119]. These EVs are considered an added demand on existing power system components, and they might have an adverse impact on the grid. The study in [120] showed that increasing EVs penetration could lead to higher short-circuit currents, off-limits voltage levels, and a shortened lifespan of the equipment. Also, the study demonstrated how fast charging of EVs caused higher losses and voltage drops when compared with regular charging. Nevertheless, with the increasing number of EVs and their potential to be used for energy trading and bidirectional energy exchange, blockchain could be the framework to automate the energy trade.  
The energy trade could be V2V, V2G, or G2V. These energy trade scenarios are depicted in Figure 6(a),b, respectively. Figure 6(a) shows the V2G and G2V charging scenarios for EVs where bi-directional energy trade can happen between the SG and Smart Homes. Figure 6(b) highlights both the static and dynamic EV wireless charging solutions and shows that V2V wireless charging can also happen under static wireless charging. Nevertheless, it is important to note that creating such an environment using the blockchain introduces new challenges.  
Namely, the scalability of blockchain data, interoperability between different blockchain platforms, privacy, data protection, and confidentiality are the key challenges in implementing P2P for EV energy trade [121; 122]. Firstly, scalability is a challenge correlated with the number of EVs. As more EVs are connected, real-time processing and communication through the chains are required. Blockchain platforms are capable of a few transactions per second (TPS); for instance, BTC is capable of 4 TPS [123].  
This is a very low number compared with credit card platform rates. Hence, a higher rate is needed to adopt more EV penetration in the SG using the blockchain. Secondly, interoperability is needed for EVs to share data across heterogeneous blockchain platforms. The work in [122; 124] argues that existing platforms do follow a defined standard. The wide adoption of blockchain for EVs is highly dependent on assuring interoperability across all platforms. In addition, security is important as there will be a large number of trades between EVs and other EVs or the SG.  
Even though blockchain favors security at the expense of scalability, security performance needs to be assessed. Reference [125] discusses different security issues encountered in utilizing IoT and blockchain, such as inherently vulnerable particularities, programming vulnerabilities, and attacks against smart contracts. Introducing a lightweight model to increase scalability could hinder security, and this is a challenge faced in implementing it for EVs. Finally, privacy, data protection, and confidentiality are crucial requirements for the successful implementation of blockchain for EV applications.  
Compliance with regulations is indeed mandatory. According to reference [122], regulations like the general data protection regulation (GDPR) are intended to limit accessibility to authorized users only. Due to the immutability of blockchain technology, which means that it cannot be erased even by authorized users, there may be a risk of compromising privacy and confidentiality. This could make blockchain non-compliant with data privacy regulations, such as GDPR [125].