By 2050, the International Maritime Organization wants the shipping industry to produce net-zero emissions. This is ambitious: globally, shipping is currently responsible for 3% of greenhouse gas emissions. Reaching net-zero is going to require rapid and widespread adoption of new propulsion technologies, including electrification.
There are some structural challenges to electrifying the marine sector. After all, there’s no charging infrastructure in the middle of the ocean. For ships that need to make transcontinental journeys without seeing ports for days or weeks, this is a challenge.
Are there segments in marine where these constraints don’t apply? It turns out there is a niche that stands out: service vessels, such as tugs or support ships for offshore infrastructure. In fact, electrification is not just viable for service vessels but can offer a significant commercial opportunity for operators.
One obvious reason that service vessels are great electrification candidates is their operational profile. They’re moderately sized ships that operate on short, repetitive routes between a small set of destinations. A service ship for a wind farm will largely repeat the same journey over its lifetime: from port to one of the farm’s turbines, then back. This means that range and electric infrastructure considerations are much easier to accommodate.
However, the reason why electrification is so exciting for service vessels is due to something else: idling.
By design, service vessels spend a large part of their operational life staying at the same spot at sea. However, they also need to be constantly ready to counteract any sudden force from a tide, swell, or gust of wind that could threaten to throw the ship off position. This is a critical safety requirement and key to preventing damage.
However, this is also costly for operators. That all comes down to some basic engineering: it’s not possible to instantly power a combustion engine up from zero to 100%. Instead, it needs to be left idling continuously so it can push back against any sudden forces. Even if the vessel intends to stay at the same spot, its engine must continuously work, burn fuel, and will be subject to wear.
This ends up being a major driver of the operating costs for service vessels. In 2019, the European Tugowners Association estimated that 15% of service vessel operating costs were due to repair and maintenance, 12% were due to fuelling, and 15% from depreciation. All these cost sources – in total, 42% of the operating cost of a service vessel – owe a lot to engine idling.
This is where electrification is a game-changer. Because an electric motor can near-instantly ramp up power, it only needs to be working and drawing power when required to apply a force. So, an electrified service vessel that’s still in calm waters uses no power at all. At the same time, it can still guarantee that it will remain stationary in the face of a gust or tide.
And, critically, since nothing within a motor is moving unless it’s applying force to the vessel, it uses up its service life much slower than an engine does.
Currently, most service vessels need to be serviced once or twice a year, and this represents an opportunity cost – these are days and weeks where a vessel is unusable. This cost is further compounded by the parts and labour for the work, and depreciation of the asset as the operating life is used up.
By contrast, an electric drive’s reduced operating time and minimal moving parts means that maintenance cycles become far less frequent and intense. This means less parts and labour costs, along with greater vessel uptime. So, while an electric drive unit can be more expensive than an engine up-front, it stands to pay for itself over its first couple of years of service through reduced maintenance cycles alone. And this is before factoring in fuel and extended service life for a vessel.
When it comes to commercial viability, electrification is a tremendous opportunity for service vessel operators. And these commercial benefits are joined by quality-of-life improvements: reduced noise, vibration, and exhaust fumes can lead to greater productivity and crew satisfaction.
All this comes together to make service vessels an ideal staging ground for electrifying maritime. That’s why, in the coming years, we should expect service vessels to be leading the charge for marine electrification – deploying the innovations that will reshape the entire industry.
James Edwards is Chief Engineer, Marine, at Helix
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