Optimising Energy Flexibility of Boats in PV-BESS Based Marina Energy Systems

Abstract

Implementation of alternative energy supply solutions requires the broad involvement of local communities. Hence, smart energy solutions are primarily investigated on a local scale, resulting in integrated community energy systems (ICESs). Within this framework, the distributed generation can be optimally utilised, matching it with the local load via storage and demand response techniques. In this study, the boat demand flexibility in the Ballen marina on Samsø—a medium-sized Danish island—is analysed for improving the local grid operation. For this purpose, suitable electricity tariffs for the marina and sailors are developed based on the conducted demand analysis. The optimal scheduling of boats and battery energy storage system (BESS) is proposed, utilising mixed-integer linear programming. The marina’s grid-flexible operation is studied for three representative weeks—peak tourist season, late summer, and late autumn period—with the combinations of high/low load and photovoltaic (PV) generation. Several benefits of boat demand response have been identified, including cost savings for both the marina and sailors, along with a substantial increase in load factor. Furthermore, the proposed algorithm increases battery utilisation during summer, improving the marina’s cost efficiency. The cooperation of boat flexibility and BESS leads to improved grid operation of the marina, with profits for both involved parties. In the future, the marina’s demand flexibility could become an essential element of the local energy system, considering the possible increase in renewable generation capacity—in the form of PV units, wind turbines or wave energy.

An intelligent energy management system for optimum design and real-time operation

“…It has been found that proper BESS charge/discharge planning can ensure system efficiency. Jozwiak et al [18] carried out an analysis of the load demand for boats in Ballen Marina to optimize the cost of energy for sailors and the cost of energy exchanged with the main grid. This proved the important role of demand flexibility analysis as a key element in the energy system.…”

Optimal Charging and Discharging Strategies for Electric Cars in PV-BESS-Based Marina Energy Systems

“…The energy price for EV charging was assumed to be the same for all cars, under the assumption of the hourly varying marina's tariff-developed in [30]. In other words, the marina was assumed to not impose any additional margin on the rental company's electricity price.…”

“…The simulations were carried out for a summer week (15-21 July 2019)-when the marina's load is highest due to the peak tourist season and rental cars are frequently used. The analysis was conducted based on the recorded boat demand of the marina from 2019, presented along with the PV generation data in [30]. The following study cases were taken into consideration: Firstly, the optimal charging strategy was developed, utilising mixed-integer linear programming optimisation.…”

“…The optimal charging was compared with the baseline scenario, in which cars are charged immediately upon their arrival at the harbour. Subsequently, the model was enhanced with boat flexibility, with the aim to coordinate the operation of the entire marina's ICES-extending the DR action presented in [30]. Further, the benefits from future V2G technology implementation were evaluated, developing the optimal strategy for bidirectional power flow between electric cars and the marina's grid.…”

“…In the future scenario, the impact of V2G technology implementation on the batteries' degradation was studied based on the employed battery ageing model. The optimisation model comprising the marina's generation, storage, electric cars, and boat flexibility was established, expanding the scope of previous research on marina energy systems [28][29][30]. The developed optimisation algorithm for the marina's energy management system-coordinating all the above-mentioned elements along with the battery degradation model-constitutes the novelty of this work.…”