You Want to Save the Planet? Change your Ships Light Bulbs, Keep a Clean Hull

Norwegian shipowners agree: the obsession with new fuels is eliding a valuable discussion of the potential of fuel efficiency. The Aurora-class has enabled Höegh Autoliners to reduce emissions by around 58% per car carried, “before we even use low carbon fuels,” CEO Andreas Enger said. “The debate between energy efficiency and the fuel transition, we consider to be irrelevant and pretty stupid,” he said. “It’s a no-brainer for a shipowner to do everything they can to reduce fuel consumption.

“Fuel efficiency itself will yield substantial improvements, it doesn’t bring us to our 2040 goal of being carbon neutral… [but] it will remain very important for new fuels, because they're going to be more expensive -- you don't want to use too much of them.”

No one is embracing this philosophy quite like Odfjell. With some 140 efficiency retrofits applied across its fleet of 70 vessels, the tanker company claims to have achieved a 53% reduction of CO2 emissions, compared with 2008, across its entire fleet.

“We have, since 2007, collected good, high-quality data from our ships,” said Erik Hjortland, Technology Vice President. “Nothing fancy – a noon report is good enough, believe it or not. In 2014 we built a robot that detects energy inefficiencies based on these numbers, and we have a separate team that deals with those alarms, and interacts with the crew to reduce the consumption.

“You can assess the energy efficiency on your ships, compare a good ship against bad, find best practice and transfer knowledge. You can also measure the effects of all energy-saving devices that you implement.”

Weather routing has proven integral to the decarbonisation of Odfjell voyages, Hjortland explained. “In 2008, our captains reported an average of 3.5m sea state … today it is 0.6, meaning our vessels are transiting in very nice weather.”

Sails, one of the efficiency devices now being fitted to Odfjell vessels, adds a new dimension to this equation. “We have to flip this a little bit upside down, because now we want wind and weather,” Hjortland said.

In March, Odfjell announced that four 22m bound4blue ‘eSails’ would be fitted to its 49,000dwt chemical tanker Bow Olympus. These are suction sails, a powered type, which use a fan at the top of the sail mast to generate suction which enables laminar airflow around the sail, thereby maximising its thrust effect. The sails were fitted at EDR Antwerp during a planned drydocking.

“We have also deployed an AI-based weather routing system… now we need to get the ships into weather,” Hjortland said. “I can say that this has so far been a success. It has delivered above our expectations on the first voyage at least.”

Operational Gains

Cleaning, Hjortland said, is another operational measure that has generated an “enormous” efficiency effect for Odfjell. Norwegian shipping seems to have taken a particular interest in increasing the number of hull cleaning operations taking place outside docking intervals. Jotun, a local paints and hull coatings company, has developed the Hullskater, a hull-cleaning ROV, with the help of Norwegian compatriot Kongsberg, and meanwhile, Norway’s ShipShave has developed a bizarre-looking robot called ITCH (“In-Transit-Cleaning-of-Hulls”).

For Odfjell’s part, the company has entered a partnership with yet another Norwegian hull-cleaning company, ECOsubsea, which used an ROV to clean its first Odfjell vessel, Bow Cedar, in Singapore late last year.

“I cannot stress enough the importance of cleaning,” said Hjortland. “It is just incredible – I have been attending decarbonization and energy efficiency conferences for almost 20 years, and for the last six, all of them talk about ammonia, methanol, hydrogen, huge projects, multi-billion dollar investments. I think it’s important to remember hull cleaning. The first 20 ships we did this on, we saved between 3.5 tons of fuel a day, on average.”

Replacing light bulbs aboard vessels with LEDs is expected to save 40-100 tonnes of fuel per vessel per year, Hjortland explained, given that there are around 700 bulbs per ship. “We took the 19 highest consumers in the fleet, did changes and adaptations on the main engine, shaft generator, new propeller, rudder dome, and without any speed loss, saved 20% on average on those ships, 30% on some. It really tells us the potential.”

Retrofitted energy saving devices, such as mewis ducts, propeller boss cap fins (“very good, cheap technologies”) have been found to return their investment cost within two years, Hjortland said -- with one notable exception. “We installed air lubrication on one of our ships in 2023. Unfortunately, this did not work. I’m not saying it does not work for anyone, but it did not work for us – we don't know why. The vendor doesn’t either. Our personal opinion is that that technology is not compatible with some other energy-saving device sets that we have on that ship.”  

Solid oxide fuel cells (SOFCs), another promising inroad, also failed. Potentially, SOFC would allow conversion of fuel into electrical power at a much more efficient rate, by skipping the combustion stage. But the componentry is not widely available. “This was terminated last year,” Hjortland said. “The short answer is, because of the economics and finances.”

The More the Merrier

The savings gained through Odfjell’s efficiency drive illustrate the importance for all of shipping to take an interest, insisted Hjortland. “We have reached 53%, we want to move to 57%. According to a Clarkson’s study earlier this year, 63% of the world fleet has not installed any energy saving devices. Imagine the potential of what we as a sector could have accomplished if everybody has done this.

“If we target e-fuels… for every kW hour [generated from a wind farm], you lose 30% producing green hydrogen. Then you lose another 30% when you use that to make green ammonia or green methanol. And then you lose 50-60% of the energy in the engine of the ship. From 1kWh, you end up with 0.2 -- an 80% energy loss.

“This we find problematic. It is bad energy economics. And this is the reason why we find sails to be so elegant on our ships, because then you harness the wind power directly. You only lose 10% percent of it from the sail to the propeller. All sectors are chasing zero, all sectors need renewable electricity to get there.”