# Energy Trading with Electric Vehicles in Smart Campus Parking Lots
## 1 Introduction  
The grid integration of electric vehicles represents a unique and complex problem for the distribution power system. This is due to the fact that electric vehicles act as loads while charging, energy storage systems during the idle state, and distributed energy sources while discharging. Different schemes have been considered in order to coordinate the charging/discharging process of electric vehicles including grid control using incentives and time-varying prices supported by the grid operator [1]. In South Korea, Korea Electric Power Corporation (KEPCO) is the sole electric power provider. The current process of energy transactions in KEPCO prohibits direct energy trading between prosumers and consumers. Therefore, all energy transactions among consumers and prosumers must go through KEPCO [2]. As the penetration rate and the grid integration of renewable energy sources (RES) such as photovoltaic, energy storage systems, and electric vehicles are continuously increasing, more and more energy consumers are becoming energy prosumers. Energy prosumers are able to generate part of their usage energy locally using RES while sharing the surplus energy with other consumers [3]. Considering RES and the surplus energy of prosumers, the excess energy of prosumerscan support the power grid during peak hours. However, there is a need for a new market model that enables energy trading between consumers and prosumers in the electric distribution system [4]. The new market model should provide various promising advantages in the distribution power systems including improved system efficiency, reduced system operation costs, and deferral of systems upgrade. However, the realization of the new market model will require a reliable communication network to support the real-time information exchange among electric vehicles. Considering the increasing number of electric vehicles, the system should be scalable to handle a large number of energy transactions among electric vehicles as well as maintain security and privacy for end user data. Peer-to-peer energy trading is a new energy trading arrangement between consumers and prosumers in the distribution power system. The authors in Ref. [5] presented a survey on energy trading in the smart grid in view of enabling technologies, required frameworks, and desired outcomes. The authors highlighted the key enabling technologies that are required for energy trading including an energy storage system, renewable generation, electric vehicles, and communication. In Ref. [6], the authors provided a review of existing peer-to-peer energy trading projects. Some of the energy trading projects have focused on building business models and platforms to support energy trading among members. Examples of these projects are those done by Vandebron, Picl, and the Sonnen Community. Other projects have targeted the information and communication technologies (ICT) for energy trading such as the PeerEnergyCloud project and the Smart Watts project. With respect to electric vehicles, the authors in Ref. [7] presented a novel energy trading method between two sets of electric vehicles. The first set includes drivers who can complete their daily activity with an excess of energy in their batteries. The second set includes drivers who need intermediate charging to complete their daily activities. Considering the grid price and vehicles' mobility, an aggregator is considered to determine the trading price, and vehicles with excess energy are allocated with vehicles that need to be charged at the same time and in the same area. The authors in Ref. [8] proposed three representative market models for peer-to-peer energy trading in a community microgrid with photovoltaic systems. The three market models are bill sharing, mid-market rate, and the auction-based pricing strategy. Energy trading with electric vehicles is expected to play an important role in the future distribution power system supported by individual charging stations in home garages, public/private parking lots, and fast charging stations.