# Boat-to-Grid Electrical Energy Storage Potentials around the
## 1 Introduction  
### The Potentials of Using Vehicle-to-Grid Technology  
Today, it is a widespread belief and hope that electric vehicles (EVs) will play a key role in reducing greenhouse gas emissions by tapping into renewable energy sources. In addition, the ever-growing demand for fossil fuels is becoming critical, concerning the costs and the general availability of these resources. In the quest to solve global environmental issues, the vehicle-to-grid (V2G) technology is one of the most recent trends, which is based on the ability of EVs to feed power into the grid when it is needed [1, 2]. While using individual EVs for this purpose is not as useful as other battery-based storage solutions, or even generators, with the advances of EV infrastructure seen today and expected in the future, EVs may be a viable alternative to contribute to maintaining power grid stability [3, 4]. During their conventional operation, EVs only receive electricity from the grid, whereas the V2G mode of operation is bidirectional, involving receiving power as well as feeding it into the grid [5]. The batteries in V2G operation are charged and discharged depending on technical and economic conditions [6]. Thus, they work in a way resembling the operation of other battery energy storage systems; however, most of those are stationary, while EVs are mobile by definition [7]. The benefits for utility grids offered by the V2G technology are manifold, since it is capable of supplying a part of the load demand, importantly, also during peak times. The EV energy thusly injected into the grid means peak load cutting for the system [8]. The intermittency of power production [9] can also be lessened by V2G [5], for example in the case of wind turbines [10] or solar power generation [11]. The ideal dispatch provided by V2G can enhance the dependability of the entire network [12]. More complex and sufficient operation can be achieved by the coordinated power management of EV charging load coupled with other technologies, for example various energy storage systems, photovoltaic (PV) systems and demand response programs. Users of models such as that may participate in the frequency containment reserve and day-ahead markets in order to make a profit [13]. It must be noted here, however, that it is not an easy task to accurately assess the combined technical effects of EV charging stations and PV power generation on the power grids because of the fluctuations in loads and electric energy generation, which calls for precise analytical techniques [14]. The V2G technology may be useful in micro energy systems, such as homes and other buildings [15], as it has the capacity to store energy at times when prices are low and discharge it when they go up, resulting in saving costs for end users [16]. Homes with renewable energy and V2G also enjoy the benefit of the ability to supply the demand and having a back-up in case of electricity outages [17]. This makes the vehicle-to-home concept an efficient approach to managing energy in the home [18]. Evidence shows that V2G is a suitable solution for the operators of microgrids [19], where the demand response can also be modelled by V2G operation [20]. All in all, it can be concluded that V2G makes a favorable impact on microgrid energy management [21]. As the use and benefits of V2G are versatile, as stated above, it can also be used for several purposes in active power markets, such as frequency regulation, peak load shaving, providing base load and spinning reserve capacity. Concerning power quality services, it can be successfully applied for motor starting, voltage improvement, reactive compensation and active filtering of harmonics. The charging stations of EVs can also serve as a kind of reactive power compensator [22]. By managing PV energy and EVs together, smart charging and V2G operation can decrease power ramps, shave the on-peak load demand and enhance system operation altogether.