By
Guest contributor |
Scrubber economics have traditionally been straightforward for operators running high-frequency routes across the North Sea and Baltic approaches. They installed an exhaust gas cleaning system, continued burning high sulphur fuel oil (HSFO), and captured the spread between HSFO and compliant fuels such as very-low sulphur fuel oil.
That calculation is changing in Northern Europe. Discharge rules and volatile bunker markets are reshaping how ferry operators think about scrubber operation.
As part of their aim to protect the marine environment in the North-East Atlantic, the OSPAR contracting parties have agreed on a roadmap to phase out open-loop discharge from scrubbers in inland waters and port areas. Open-loop discharge will be banned from July 2027 and all discharges will be prohibited from July 2029, although implementation may vary by country. The areas covered by these restrictions are exactly where ferry services spend much of their operating time.
Short-sea passenger shipping operates very differently from deep-sea trades. Ferries run fixed schedules with frequent port calls. Manoeuvring, loading and passenger operations mean ships spend several hours of each cycle inside port waters. Even when ferries are berthed alongside, auxiliary engines continue running to power accommodation spaces, restaurants and onboard services. That power demand is not optional. Passengers expect functioning cabins, hot meals and climate control, and the engines run regardless of what fuel economics look like that week.
On busy overnight routes, these hotel loads can represent a substantial share of daily energy demand, meaning fuel strategy is closely tied to passenger operations as well as propulsion.
Norwegian ferry operator Color Line’s overnight services on the Oslo–Kiel route between Norway and Germany, and the Sandefjord–Strömstad route between Norway and Sweden, show this clearly. Both operate entirely within the North Sea and Skagerrak waters covered by the OSPAR framework. A large share of each voyage therefore takes place in coastal areas where discharge restrictions apply.
Ships fitted solely with open-loop scrubbers must switch to compliant fuel during these periods. The process itself is routine, but the commercial implications depend heavily on how much of the voyage falls within restricted waters. On ferry routes with daily port calls, that share can be substantial.
Scrubber economics ultimately depend on how many hours a vessel can burn HSFO. Early investment models assumed relatively high utilisation, with ships operating most of the time in waters where open-loop systems could discharge freely. As discharge restrictions expand in port areas and coastal zones, that assumption becomes less reliable.
For ferries running short rotations, even small changes in operating patterns can have an outsized effect. A vessel that spends several hours of every voyage inside restricted waters reduces the total window available for HSFO use. Over the course of a year, those lost hours can materially alter the fuel savings originally used to justify a scrubber installation.
Operators have already begun adjusting to this reality. Color Line has upgraded several vessels with hybrid exhaust gas cleaning systems capable of operating in both open and closed-loop modes with zero discharge. The arrangement allows scrubbers to operate in open waters but remain compliant when entering ports or other restricted zones, preserving HSFO utilisation across voyages that move repeatedly between both environments.
This type of flexibility reflects the operating environment across Northern Europe. A single voyage can involve unrestricted waters followed by port approaches and coastal areas with different discharge rules.
Frequent port rotations across the North Sea and Baltic approaches bring these dynamics directly into daily operations. The scrubber decision no longer depends only on the headline price difference between HSFO and compliant fuels. Route structure and regulatory geography now interact much more closely.
For ferry operators in Northern Europe, the question is no longer simply whether to install scrubbers. It is about which configuration will enable vessels to continue operating as regulations tighten and fuel markets shift.
Kashif Javaid is director of sales and exhaust treatment at Wärtsilä Marine
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