# Boat-to-Grid Electrical Energy Storage Potentials around the
## 3 Results
### The Number of Sailing Marinas and Berths around Lake Balaton
It can be seen that boats with powers of 6-20 kW account for 68.5%, followed by the category of boats with 21-40 kW at 24.4%. Boats with powers above 40 kW or below 6 kW are not significant yet; they represent a mere 7% of the current fleet of small electric boats. Figure 6: The 10 most significant resorts of Lake Balaton in terms of berths for sailboats, based on [55]. Figure 7: The distribution of the small electric boats in the sailing marinas of Lake Balaton by the power of their electric motors, own results. Currently, the small electric boats in the sailing marinas occupy 3.1% of the total of 6 891 berths. Nevertheless, it is important to point out that, based on today's data [57], the ratio of electric berths is expected to reach 10% of the number of total berths, which development is projected to be linear until 2030. The available data and the results were applied in a linearly proportional way for the year 2030 [57; 59; 60]. On the basis of the data provided by the Government Agency of the City of Budapest [57], Stickl Yachts Ltd. [60] and AQWIA Ltd. [59], the average and total energy storage capacities belonging to each electric boat motor power were also established. The averages of the energy storage characteristics of the electric boats vary, as shown below:  
* \(<\)6 kW, 12 kWh on average;
* 6-10 kW, 15 kWh on average;
* 11-20 kW, 18 kWh on average;
* 21-40 kW, 36 kWh on average;
* \(>\)40 kW, 50 kWh on average. Figure 8 shows the distribution of the energy storage capacities of the electric boats by the power of their electric motors. It is obvious that the lion's share of the energy storage capacity of the electric boats belongs to the small electric boats with powers ranging 21-40 kW with approximately 1.9 MWh, followed by vessels with powers of 11-20 kW accounting for 1.5 MWh and then the third category of 6-10 kW representing almost 1 MWh. The rest of the of the boats with motors \(<\)6 kW and \(>\)40 kW feature a total energy storage capacity of more than 0.5 MWh. From these data, it follows that the 213 small electric boats in the sailing marinas of Lake Balaton represent an energy storage capacity of 4.8 MWh altogether. This is merely 21% less than that of one of Hungary's largest battery energy storage facilities (6.1 MWh), the one belonging to ELMU-EMASZ Energy Service Zrt. in the south of Buda (Budapest). In 2021, the investment costs of a Lithium-ion-based energy storage system of a storage capacity of 1 kWh typically amounts to about USD 300 [69], which means that the aggregate energy storage capacity of these small electric boats represents a value of approximately USD 1,440,000. The existence of the aggregate storage capacity of the small electric boats is also good news because, if suitably regulated, this capacity can contribute to the more optimized operation of grid-connected solar power plants and household-sized PV systems (called HMKE in the Hungarian regulation, connected to the national grid by definition) around Lake Balaton, e.g., during the periods of peak load demand. It is also worth noting  
Figure 8: The distribution of the total energy storage capacity of the small electric boats in the sailing marinas of Lake Balaton in 2021 by the power of their electric motors, own results. that the greatest penetration of HMKEs in Hungary at the end of 2019 was in the north of the Great Plain region, along the north-western border of the country, in Budapest, around Lake Balaton and in the major cities (Figure 9) [70]. According to the data in Table 1, an energy storage capacity of 4.8 MWh could even allow the regulation of a PV system of 24.1 MWp. Provided the number of electric berths reached 10% of the total number of berths in the sailing marinas, thanks to the developments in the region of Lake Balaton, that increased capacity would be suitable for enhancing the security of supply and control over the system.