GIFT Project E-ferry findings

The Horizon 2020 GIFT project contract 804410 aiming to support a sustainable energy mix in European islands. As one of the pilot leaders, Hafenstrom has calculated emission profiles and run simulations integrated with digital twins for the islands’ grid. Through this process, Hafenstrom has gained new insights in the role of e-ferries as energy flexibility prosumers.

eFerries with short layover time cannot serve as a prosumer

e-ferries with short layover time cannot serve as prosumer that provide energy flexibility to the energy grid. It is only if they stay at the quay for a longer duration that the battery’s State of Charge (SoC) may provide effect flexibility to the local grid.

Digital models have been used to examine and compare the load profile with charge profiles. Normal charge profile is based on high effect usage, until a SoC of around 80% has been reached. Basically, the Battery Management System (BMS) determines the effect being used, while the ferry’s Energy Management System (EMS) and the energy necessary to recharge onboard batteries. There is theoretically not any difference between e-Ferry with regards to how SoC influence the effect flexibility. However, other vehicles are normally more flexible with regards to scheduled arrival and departure.

Graph 1: A virtual ferry will have the same impact as a physical on flexibility offer that will be given. The load on the power grid is related to the timetable, as graph 2 also indicates.

There is no need for a physical ferry to deploy energy flexibility management

Knowledge and data about chargers located on the quay, such as charging profiles and charging time is more relevant than having a physical e-ferry on the demonstration site. Research and analysis showed that by having the right data from the demonstration site such as the route table of the ferry and its timetable, the model, status and capacity of the e-ferry charger can be used to calculate and deliver flexibility offers.

These findings have led to the inclusion of route tables as the most valid source of information for making Flex offers. Most of the consumption data is known based on existing load profiles, hence allowing for a virtual representation of e-ferry. Therefore, Hafenstrom developed a solution named “Harbour Energy Flexibility Manager” (HEFM) as part of the GIFT project. This solution takes into account route tables, harbours with available quays and chargers based on models, status, capacity and availability. Information used here is combined with vessel information such as configuration and position. Finally, several different trigger conditions such as time, position, energy demand with more can be used as basis for flex offers offered to a party with the role “Flex agent”.

Graph 2: Each peak on the chart comes from an e-ferry arriving at the dock facility for charging. These charging times are directly correlated with the timetable times. The charging profiles shown are also predictable. Therefore, knowledge about battery charging profiles and charging time is more central than purely physical arrivals and departures as these are reported from e.g., chargers located on the quay.