Onshore power systems: Why vessels should be plugged in

A new onshore power system provides ships at the Port of Kiel with sustainable power.

Cruise ships and ferries have become a burden in many ports, especially because of the emissions from their diesel generators. Now, thanks to a new onshore power system in Kiel, it’s possible to supply ships with renewable power via the local power network. The result is cleaner air, more peace and quiet for the port city, and less CO2 impacting the atmosphere. 

No stress, plenty of variety, and moderately priced: Cruises are very popular with vacationers. The number of cruise passengers almost doubled between 2009 and 2019, from 17.8 million to about 30 million every year.


At the beginning of 2020, there were 278 sea-going cruise ships in operation, and 28 new vessels are being delivered in 2021 alone. And in addition to the cruise capacity on the open sea, there are more than 500 cruise vessels operating on inland waterways. Even if the pandemic disrupted ship-based tourism for almost a year, we can expect the demand to grow again over the next few years.


But even so, cruise trips aren’t free from controversy, especially because of the ships’ environmental footprint. The impacts are particularly evident in port cities. Barcelona, Marseilles, Piraeus … Ports like these may benefit from these ocean-going giants, but they also have to live with the flip-side of cruise-based tourism. What applies to cruise ships naturally applies to other ships - be they ferries or cargo ships.  

Port of Kiel reduces emissions from ships

The main problem is that the electricity on these ships is supplied by onboard diesel generators, which are left running while the vessels are in harbor. The noise and vibration from these giant generator sets disturb nearby residents, while exhaust gases impact the air quality and climate.


The authorities in the north German port city of Kiel were no longer willing to tolerate this situation. Kiel is a popular departure point for cruises and is also the starting point for ferries bound for Norway, Sweden, and the Baltic. About 2.4 million passengers pass through the terminal facilities in Kiel on their way to or from ships of one kind or another. 

Onshore power system ensures clean air and reduces CO2 emissions

To minimize the environmental impact and the health risks for nearby residents, the Port of Kiel decided to enable ships to obtain their electricity supplies from the local grid while in port, instead of having to continue generating it using their diesel engines. “We’re working on a way to plug ships in to the electricity network,” says Dirk Claus, Managing Director Port of Kiel.

By building this new onshore power system, we’re actively supporting the city’s climate objectives.
Dirk Claus, Managing Director Port of Kiel

That allows port operators to supply the ships with power from renewable sources like photovoltaic plants and wind turbines: “By building this new onshore power system, we’re actively supporting the city’s climate objectives,” Claus says. The port conserves about 12,000 metric tons of CO2 annually, equal to the amount emitted every year by 2,600 passenger vehicles.


Reducing greenhouse-gas emissions is just one benefit. Thomas Kopel, Senior Sales Engineer at Siemens, explains: “Switching off the engines while in port reduces harmful emissions, noise pollution, and vibration.”

Tailored to the needs of the port

Kiel designed its new onshore power system to provide a simple, fast, and flexible connection between land and ship. Siemens employed a new cable-feed system for this purpose. There’s also another new feature of the onshore power system: It’s the first of its kind that’s capable of supplying two ships with electricity simultaneously.


That means it optimally covers the needs of the Port of Kiel: “We’re trying to supply two ships simultaneously for the first time with this system, a ferry and a cruise ship. The goal is to supply onshore power to all the city terminals,” Claus explains.

Lots of power and smart power electronics

To supply ships the size of a small town with clean electricity, the onshore power system needs to manage a lot of power: 16 megavolt-amperes (MVA), in Kiel’s case. But that isn’t all it needs: Onboard networks operate using different voltages and frequencies than the local power network. That’s why supplying the ships from the mainland requires additional power electronics capable of managing these differences.


Kiel’s solution is SIHARBOR. This converter system developed by Siemens also includes software that can be used to provide central control for the various berths. In Kiel, SIHARBOR synchronizes the two ship networks and automatically begins the supply process just a few minutes after being connected. The system continuously coordinates the autonomous ship networks in order to ensure an efficient and uninterrupted supply.


SIHARBOR is part of the Siemens SIPLINK portfolio, which is also used in Kiel. In addition to converters, it comprises all the other key electrical and electronic elements of onshore power systems, including medium-voltage switchgear, transformers, network filters, and automation. 

Cloud-based power monitoring creates transparency 

Kiel is the first port to have Siemens equip its system with a cloud-based power monitoring solution. It gives the port operators an overview of all relevant performance data, regardless of time and location. As a result, they always have a transparent view of power consumption plant data.


Should a fault ever occur, the cause can be determined quickly thanks to automatic notification and rapid fault localization. This prevents downtimes, and maintenance routines can be planned better. The measurement data is stored in MindSphere, the cloud-based IoT system from Siemens.


Based on this data, plant operation can be continuously improved and adjusted to meet new requirements. “One thing we can’t forget,” observes Stephan May, CEO Smart Infrastructure Distribution Systems, “is that the port is a living complex, so of course we provide our customers with support and will continue optimizing the system throughout its entire lifecycle.”

Model solution for other port cities?

The onshore power system in Kiel provides an example of how the environmental consequences of cruise-based tourism and ferry traffic in port cities can be dramatically mitigated while also saving large amounts of fossil fuel.


Although the technology has been available for years, only a few ports have been equipped with systems of this kind. In the case of cruise ships, there are two main reasons: There’s the classic chicken-and-egg problem, in that the owners have to convert their ships to make an onshore power supply possible. They’re often hesitant to make the necessary investment, because only a few ports have the appropriate power connections. And on their part, ports are hesitant to build the necessary infrastructure because only a few ships are able to make use of it. 


In the EU, at least, the taxation system distorts the market: Whereas onshore power is taxed in accordance with the 2003 EU Energy Taxation Directive, fossil-based ship fuels are still exempt from taxes. So far, this has been another factor that discourages ship owners from opting for an onshore power supply.

We need to keep driving the maritime energy transition forward.
Peter Altmaier, Germany’s  Minister of Economic Affairs and Energy

But things are starting to move: In its climate protection strategy, the European Green Deal, the European Commission provides for an obligation on ports in Europe to make onshore electricity available. In joint memoranda of understanding, ports worldwide are undertaking the construction of onshore power systems.


Many governments are actively sponsoring the construction of these systems, not just to supply ferries and cruise ships but also for cargo ships. That includes Germany: By 2023, the federal government will have made available a total of €176 million in financial assistance to set up onshore power systems in its maritime and inland port facilities.


Peter Altmaier, Germany’s Minister of Economic Affairs and Energy, affirms: “Even if ships are already one of the most environmentally friendly means of transportation in terms of their capacity, we need to keep driving the maritime energy transition forward.” Siemens offers the technology required to make these goals a reality.

September 23, 2021

Picture credits: Port of Kiel, Siemens

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