Shore power is becoming critical to ports and the vessels they serve being a significant factor in ports’ overall carbon management strategy, highlights a newly published white paper by The ModOPS Project, discussing key challenges.
In order to achieve the rate of decarbonisation required to meet net-zero targets (eg in the UK Clean Maritime Plan and the EU ‘Fit for 55’ strategy) workable solutions are needed now. The roadmap towards maritime net-zero is beset with uncertainty and will involve a range of novel fuel and power solutions in ports.
As vessels decarbonize in line with national and international net-zero policies, many ports will become unable to access all the required power from their grid connection cost-effectively, so other solutions are needed. However, ports need to start investing now in the infrastructure they will need.
The ModOPS project, supported from DfT’s TRIG programme, has analysed the complete energy flow from source to vessel, under a range of use cases and for different energy vector options. In this white paper, it analyzes key challenges ahead, considering that, when it comes to shore power, the big question is:
what should that investment plan include in order to minimize the risk of creating ‘stranded assets’ which become obsolete as decarbonization options mature?
As such, it is important to consider the following:
- Security of supply – will the port be able to access sufficient energy and power to meet the needs of visiting vessels and in-port facilities at times of high demand?
- Compatibility – how will shore power facilities work alongside other fuel systems needed in the port (eg for bunkering)?
- Cost – will vessel operators be willing to pay the price of energy offered by the port, taking
account of future pressures within the market for fuel? - Risks – are there significant risks of technological obsolescence or failure to meet future safety standards?
- Efficiency – losses incurred in converting energy resources procured by the port into onboard energy will determine costs and increase the capacity of supply chains needed.
The performance of a shore power system depends strongly on its use case: not only the energy throughput but also the intermittency of provision. In order to cover a wide range of sizes and duty cycles, six real-world use cases have been defined and modelled:
- UC1 Short-distance passenger ferry (eg Gosport ferry) with all-electric propulsion – Batteries need recharging at each berthing drawing typically 250kW during 6 minutes at berth, with four crossings per hour.
- UC2 Medium-sized cruise ship (eg Noble Caledonian), hotel load only- Average 450kW drawn over 8 hours berthing time, with weekly ship visits in season
- UC3 Short/medium-distance RoPax ferry (eg Victoria of Wight), hotel load only – Average 350kW drawn over a 30min berthing time, with vessels berthing at roughly 1 hour intervals
- UC4 Cross-channel ferry fleet (eg Brittany Ferries), hotel load only – Average 1.5MW power draw for a typical duration of 2 hours at berth, with 2 or 3 services per day on average
- UC5 Windfarm support offshore vessel (SOV), hotel load only – Average 250kW power draw over a 24 hour period to replenish crew and inventory, every ten days typically
- UC6 Nearshore fishing vessel, hotel load only – Average power of 15kW over a period of 12 hours at berth, every day.
Although direct electrical connection of shore power systems to the port’s grid connection is the default solution, several alternative options have been considered:
• Electrical connection with in-port battery storage;
• Hydrogen in-port energy storage with conversion into electrical energy;
• Methanol in-port energy storage with conversion into electrical energy;
• Diesel, HVO or DME in-port energy storage with conversion into electrical energy.
The paper notes that the options are much more limited for ports lacking convenient access to energy at the capacity dictated by their shore power demands. Battery storage can maximise shore power capacity from a fixed grid connection capacity, especially for serving vessels that impose a very intermittent load. However, longer term growth in shore power demand is very likely to exceed the limitations of existing grid connections for most ports.
Where an all-electric solution is not feasible or unattractive, on-site generation of electricity using fuels transported into the port is an alternative option, the project concludes, adding that conversion of the hydrogen into a liquid fuel such as methanol (ideally at scale to minimize the additional process costs) appears to be a more cost-effective solution, since the liquid fuel can be transported and stored safely using proven technology. Hydrotreated vegetable oil (HVO) is also a useful transition fuel as a drop-in replacement for diesel. Liquid fuels like HVO and methanol can be conveniently burned in a conventional diesel engine (with some modification for 100% methanol or aquamethanol) with significantly lower emissions than diesel.
