The role of onshore power supply in the green transition

Published — May 10, 2024

The FuelEU regulation comes into effect on 1 January 2025. This regulation will be an industry game changer as it requires all vessels calling at European Union (EU) ports to decrease the emissions intensity of fuels, thereby leading to an increase in the use of alternative fuels over time.

That’s not all. According to one of the rules in the regulation, container and passenger vessels at EU ports must use onshore power supply (OPS) (or an equivalent zero-emission technology) for their energy needs when at berth instead of using fossil fuels or alternative fuels. This rule comes into effect on 1 January 2030. The use of OPS can significantly reduce pollutants such as sulfur oxides (SOx) and particulate matter (PM) emissions, and modestly reduce nitrogen oxides (NOx) in ports1 but it will require overcoming cost and regulation challenges.

We spoke to Jenny Ruffell Smith, a secondee from John Swire & Sons working with the Maersk Mc-Kinney Møller Center for Zero Carbon Shipping (MMMCZCS), to find out more about the technology and how to ensure that the use of OPS reduces emissions at ports.

Onshore Power Supply

“When vessels are at berth, they require electricity for a range of purposes, including air conditioning crew quarters; running pumps, cranes and other cargo handling equipment; heating or cooling of cargo; etc.,” says Jenny. “The electricity needed can either be generated on board via auxiliary engines and generators or generated from shore. When they are generated from shore, they are called onshore power supply or OPS.”

If a ship at berth uses electric power from the shore to power its various needs, then it is not burning an equivalent amount of fossil fuel. This eliminates emissions from ships in port waters, and reduces pollutants and greenhouse gas emissions. It also reduces noise, vibrations, and engine wear and tear.2 One estimate suggests that using OPS can reduce emissions by 2.2% annually.2

“Electricity from OPS will be counted as zero regardless of the composition of the local electricity mix in FuelEU. This is justified by the Renewable Energy Directive (RED) which sets a target on decarbonization of the electricity grid,” says Jenny. “However, it is important to recognize that while the implementation of OPS significantly reduces emissions at the port and contributes positively to the community and local environment, the full potential of this initiative is contingent upon sourcing the electricity from renewable energy.” She adds, “For instance, utilizing electricity generated from coal rather than wind compromises the renewable aspect of onshore power, thus diminishing its overall benefit to the port and surrounding areas. Ensuring the electricity for OPS is derived from sustainable sources is essential to maximize its environmental advantages.”

In that sense, RED complements the FuelEU regulation.3 RED sets the objective for the EU to produce 42.5% of its electricity from renewable sources by 2030, while FuelEU is about using OPS which should be pulling power from renewable sources.3

The European Parliament stresses that onshore power supply has a “key role” to play in making shipping greener. The EU is not alone in this view; countries such as China and Norway, and the American state of California, already have either OPS-related regulation or OPS options in place.4

Replacing fossil fuels with electric shore power can have significant environmental benefits. However, detailed calculations of emissions of vessels while at port can be complicated given the uncertainty of shipping emissions on individual voyages and days spent at ports.

The challenges globally

The demand for power while at berth varies depending on the vessel type, size, type of cargo, location of the plug, etc. For example, passenger vessels, liquified gas carriers, oil tankers and container vessels consume more electricity at berth than other vessel types.4 “This means that requirements for OPS also differ across vessel types,” explains Jenny. “OPS is a mature technology but for a port to provide the facility, it needs to take into account the vessel type, location of the plug on the vessel, voltage, frequency, and current, among other factors. The port will also have to provide cables and equipment, and qualified personnel to handle them.”

Let us take the example of a cruise vessel and a container vessel. A cruise vessel requires a voltage of either 6.6kV or 11kV and a power demand averaging from 3-4MW for the smaller vessels and up to 16MW for the larger vessels. A container vessel requires a voltage of 6.6kV and a power demand averaging from 1.5MW for the smaller vessels and up to 7.5MW for the larger vessels. It would be a challenge for a port to provide the necessary amenities that cater to all vessel types and demands for power.

It is equally expensive and challenging for ship owners to standardize their vessels. The investment cost to convert existing passenger and container vessels to accept external power supply is high. It is also more expensive to use onshore power than it is to burn fuel on board. This is despite the fact that using onshore power should reduce the wear and tear on the engine, thereby reducing the maintenance required.

“From the discussions we have had with the industry, we learnt that the high capital costs involved for both shipowners and ports and the lack of a revenue model to support them is one of the reasons behind the industry’s lagging interest in investing in onshore power supply, despite the fact that OPS can help reduce emissions,” says Jenny. “There are also risks in the financing of OPS investments due to uncertainties of grid capacity and access, electricity sales forecasts, and green power supply. In Europe, these risks are mitigated by the mandates for OPS in the alternative fuels infrastructure regulation (AFIR), which covers Trans-European Networks (TEN-T) ports.”

The second challenge is related to uncertainties surrounding the future of OPS and global regulation. “We see that regulations are in place, but they are varied. Today, various countries, ports and shipowners have created rules and solutions in isolation,” says Jenny. “The lack of standardization (type of connection required, voltage, power, frequency, etc.) and compatibility of OPS can lead to over or under investments in capacity at both the OPS facilities in terminals and in the electrical grid in and around ports.”

An interesting example of this challenge can be found in the state of California in the USA. Differences in port authority safety requirements have resulted in the Port of Oakland and the Port of Long Beach providing two different OPS solutions. These issues could be solved by further alignments on areas such as ports system commissioning, safety standards, alarms and protections, and voltage supply. “It is important that we find solutions that are standardized across the globe,” Jenny explains.

Opportunities and Recommendations

“Despite these challenges, industry representatives we spoke to agreed that OPS use has environmental benefits and its ability to reduce emissions make it an attractive option once the risks are mitigated,” says Jenny. One port has already successfully shown the way. The Port of Bergen in Norway partnered with Plug — an onshore power supplier owned by the local energy company, Eviny — to provide onshore power from renewable sources to passenger and supply vessels. They started with only one OPS system in 2015, but as of December 2023, had 8 OPS systems with 21 supply pits. Most vessels which call at the Port of Bergen now connect to OPS, due to shipping companies’ concerns about their environmental impact and goals to reduce emissions.

Plug has expanded its services to several other local ports and will soon expand overseas to Scotland. While there are still challenges, the team at Plug has learnt important lessons such as cataloguing all the ships that call at the port before considering installation of OPS (types of vessels, type of connection required, voltage, power, frequency, etc.) to ensure the most suitable option is picked.

The authors of the recently-published CE Delft report4 consider OPS to be a viable long-term solution to reduce air pollutants, noise, and greenhouse gas emissions. At the same time, connecting to OPS facilities while at berth offers a way for vessels to improve their Carbon Intensity Indicator performance. However, barriers remain, including lack of funding, lack of coordination in regulation, lack of detailed and reliable power consumption data, forecasts considering further electrification of vessels, standardization for certain vessel types, and low voltage OPS connections.5

“If OPS is to become a global opportunity, then the shipping industry needs further support,” says Jenny. This support can take the form of public financing of shore-based infrastructure, competitive electricity pricing, regulation for ports/terminals to make the provision of shore-side electricity mandatory as is the case in the EU6, and regulation for ocean-going vessels to make shore power mandatory. “The grids that supply energy to the ports also need financial and regulatory support,” says Jenny. “Decarbonization of the shipping industry is in progress and OPS is a readily available solution.”


1 B. Anderson et al. Study of emission control and energy efficiency measures for ships in the port area. (2015).

2 Stolz, B., & Held, M., Georges, G., & Boulouchos, K. The CO2 reduction potential of shore-side electricity in Europe. Applied Energy, 285, 116425. (2011).

3 Cruise Lines International Association. Onshore Power Supply (OPS) – deployment and use for cruise operations. (2023).

4 Faber, J., van den Berg, R., & de Vries, J. The role of shore power in the future maritime fuel mix. CE Delft. (2022).

5 ICS, IAPH, CLIA, & Interferry. Reduction of GHG Emissions from ships. Marine Environment Protection Committee, MEPC 80/7/6. (2023).

6 Regulation (EU) 2023/1804 of the European Parliament and of the Council of 13 September 2023 on the deployment of alternative fuels infrastructure, and repealing Directive 2014/94/EU. Official Journal of the European Union. (2023).

If you want to know more, feel free to reach out to:

Jenny Ruffell Smith