# Boat-to-Grid Electrical Energy Storage Potentials around the
## 1 Introduction
### The Importance of Energy Management Systems  
An energy management system involves the planning of both energy demand and supply, as well as smart energy management, which connects the two sides. For the efficient implementation of energy management systems in ports and marinas, it is of paramount importance to measure and estimate their energy consumption accurately. Besides these, an established management strategy is also necessary [26].  
While, on the one hand, the measurement of energy consumption requires the use of some device or instrument, its estimation, on the other hand, is done on the basis of perceptions and calculations. It is quite obvious that the lack of detailed energy consumption data makes the use of methods aimed at energy efficiency more difficult, and thus, it creates problems in focusing attention on the right area, operation or equipment. Consequently, the assessment of the effects of energy efficiency methods, for example their economic (the possibility of making use of lower energy prices during certain periods) or environmental (GHG emission data, carbon footprint calculation) impacts is compromised too [26].  
Monitoring the energy consumption in real time, however, can increase the flexibility of energy management [27]. Unfortunately, since the installation of special equipment is needed for real-time measuring, it is also relatively expensive most of the time. Systems for monitoring energy consumption in real time, which are linked to real-time operations monitoring [28], can be comprised of a smart meter and smart energy management systems [29; 30; 31].  
The various operations at ports and marinas are based on energy from different sources, including fossil fuels and/or clean energy sources, including renewable ones. The electric energy consumed is either supplied through the grid or it is produced on the premises [26].  
The concept of integrating energy suppliers (also those of renewable energy) and consumers as well as tools of controlling, monitoring, analyzing and optimizing power by enhancing communication between all components of the system is generally referred to as a smart grid [32; 33]. Smart energy management systems, whose purpose is to achieve the balance of energy supply and demand in an intelligent manner by using advanced technologies, consist of four main pillars. The first element is that of the management of energy supply (power generation, also including on-site renewable energy generation, combined heat and power [CHP] systems, grids, etc.). The second and the third components are energy storage systems (e.g., battery storage systems) and energy demand management (featuring real-time consumption measurement, among other things). The final pillar is that of optimal management and communication between all active resources (by means of various methods of optimization, peak shaving, load diagram control and utilization management in the grid) [29; 34]. In general, smart grids and microgrids can have a variety of applications in buildings, warehouses and urban areas [32; 35]. More specifically related to port (or marina) operations, smart grids can provide integrated port-grid platforms consisting of electricity grid technologies [29], advanced smart meters, sensor technologies, [36; 37; 38], systems for real-time monitoring [39], battery technologies, control tools [40] and technologies for communication. Smart grids and microgrids are forecasted to supplant conventional grids in ports in the not too distant future [40]. Following the general, upward trend, ports are also producing more and more renewable energy, which can be put to use either directly on the premises or it can be fed into the grid. However, as relatively few ports have already installed their smart grids, there is still room for improvement in this respect. Some sources also claim that the ports of the future will also have their own combined heat and power plants, and they will even be used as facilities for carbon capture and storage [26].