Designing today’s next-gen OSV for tomorrow’s opportunities

A veteran offshore shipmanagement executive, Mr Knox said Capital’s intention as a first mover in OSV newbuilds was to “push the envelope” of the design, adding features like shore-power connection systems well before the infrastructure was available in Brazil. Through his board membership at the Montrose Port Authority in the UK, Mr Knox has seen first-hand the fuel savings that can be achieved using shore power. He said Capital hopes to see it adopted elsewhere in the world.

He described the vessel’s diesel-electric and battery-hybrid propulsion technology as “cutting edge” for Brazil, noting it would “reduce fuel consumption, reduce emissions and reduce maintenance costs, future proofing it for tightening environment regulations and ESG expectations”.

“Flexibility is about ROI”

How flexible is it? He said the MPSV has the capability to support light construction, ROV operations and subsea work, and perform offshore wind work. “It has a moon pool for subsea ops and has the option to add a heave compensated crane. So, again, that versatility and flexibility has been key in the design from the very beginning. Consequently, this results in lower technical risk from day one on the vessel itself and some of the more safety and accommodation factors,” said Mr Knox. He also pointed out that the MPSV is “fully compliant with SPS and industrial personnel code, so again, one of only a few PSVs in the world that will meet those requirements.” Other features are a dynamic positioning class 2 system, advanced oil recovery systems and FiFi 1 capability.

“It’s a flexible, future-ready platform designed to serve the offshore market for its entire operational life,” Mr Knox stated.

Converting experience into design

In approaching the design of the first two of Capital Offshore’s multipurpose service vessel newbuilds, Mr Agostinelli said Breeze relied on its extensive learnings from past OSV conversions, while incorporating fuel-flexible propulsion, energy storage systems and shore-power connections to underpin lower opex, improved efficiency, fuel savings and reduced emissions.

Mr Agostinelli emphasised it was critical to build flexibility into any OSV design because of the cyclical nature of the offshore energy business. “There are a lot of shifts in the market — high rates for a few years and low rates for decades,” he said, adding, “Then you need to see what to do with your assets.”

As an example, Mr Agostinelli showed a vessel from its portfolio originally designed for platform supply. He said while it had a “good life” as a PSV, it was converted and repurposed as a seismic research vessel due to market shifts. “And after this market dried up, the owner converted it to an offshore wind accommodation vessel,” he said. Flexibility is about ROI, ensuring the asset produces a commercial revenue stream over its entire lifecycle.

Ethanol as an alternative

And to meet emissions standards and industry’s decarbonisation targets, Mr Agostinelli said: “Flexibility in fuels is important in today’s world.”

And fuel choice has an enormous impact on a vessel’s design, pointed out Wärtsilä general sales manager, marine, Latin America, Mario Barbosa. He noted that Wärtsilä was a pioneer in supporting the uptake of alternative fuels. Thirty years ago, the Finnish marine technology developer introduced the first LNG dual-fuel engine, and in 2015, undertook the ground-breaking conversion of four-stroke diesel-burning Wärtsilä Z40 engines to use methanol as their primary fuel. The conversion was a watershed moment for engine technology and methanol as a marine fuel.

“Ethanol is well known in Brazil as an alternative”

“Since that time, we have been investigating methanol more deeply as an alternative,” he said, against the backdrop of maritime decarbonisation. He noted the 2022 launch of the Wärtsilä 32 methanol engine, which can run on methanol, HFO, MDO and liquid biofuels. Methanol combustion produces 50% less NOx than fuel oil, making the Wärtsilä 32 methanol engine compliant with IMO Tier II limits. Using selective catalytic reduction, such as Wärtsilä’s nitrogen oxide reducer, the engine meets IMO Tier III. Using green methanol — produced with renewable electricity — can reduce well-to-wake greenhouse gas (GHG) emissions by around 80%.

Based in Brazil, Mr Barbosa highlighted the country’s long experience with producing and using another alcohol-based fuel, ethanol.

“Ethanol is well known in Brazil as an alternative for more than four decades in the car industry and some other applications. So, we brought the idea of having ethanol as an alternative together with methanol,” he said. Partnering with local producers of renewable ethanol, Wärtsilä began testing the alcohol-based fuel in its four-stroke engines in 2024, with the goal of commercialising the technology.

First-generation ethanol can be made from corn or, as is common in Brazil, sugarcane.

Mr Barbosa examined six fuels in his presentation — low sulphur fuel oil, LNG, ethanol, methanol, ammonia and hydrogen (both compressed and liquefied) — comparing key considerations, regulation readiness, volumetric energy equivalency, and tank hold space compartment volume.

Mr Barbosa said that the vessels that use an alternative fuel “should have the same autonomy as vessels using low sulphur fuel oil.”

LNG, ammonia and hydrogen, both compressed and liquefied, present design, operational, capex and opex challenges in terms of regulations, cryogenic storage requirements, increased fuel costs, energy density and storage requirements. All these fuels present significant challenges in designing an offshore vessel.

What was evident from his comparison was that ethanol presented a very compelling case as an alternative fuel, given its ample supply in Brazil, lower toxicity compared to methanol, flexible tank arrangement, favourable volumetric energy equivalent of 1.7x and tank hold space compartment volume of 1.3X compared to LSFO.

And unlike low sulphur fuel oil, ethanol could be stored in spaces below the vessel’s waterline without the use of double hulls.

When used in place of fuel oil in an electric-hybrid propulsion system using three diesel generators, first-generation ethanol would reduce CO2 emissions by 68%. A second-generation ethanol (produced from non-food biomass) would cut carbon dioxide emissions by 74%.

“That’s why we think that ethanol can play a very important role, because it’s available, well known in Brazil and other countries, and can be produced from either sugarcane or corn,” he concluded.