From sails to wings: Maritime players innovate on fuel efficiency

ROTATING sails, hybrid boats and vessels inspired by birds – these are some of the innovations that Singapore-listed companies are deploying to improve the energy efficiency of maritime transportation as the shipping industry aims to lower its emissions and reach net zero “by or around” 2050.

Greener fuels such as ammonia and methanol are gaining traction. As The Business Times recently reported, more ships are set to be retrofitted with dual-fuel engines that can run on these fuels in the coming years.

These green fuels do not produce as much carbon dioxide when they are burned, but the trade-off is lower energy density.

This effectively means fuel storage takes up more space on a ship, said Aziz Merchant, executive vice-president for engineering, technology and new product development at marine engineering specialist Seatrium . This has in turn incentivised owners to improve the fuel efficiency of their ships.

Energy efficiency retrofits are “not just a market necessity (but) an imperative, especially for older ships lacking in eco-tech setups due to their age”, said Merchant. He estimates that almost half of today’s ships will need retrofits – for both engines and energy efficiency – by 2040 to decarbonise.

In 2023, Seatrium’s shipyards completed 46 such retrofits. One increasingly popular technology is the rotor “sail” – a cylindrical structure that sits vertically on the ship and rotates with the wind to propel the ship forward. Rotor sails can lead to fuel savings of between 3 and 15 per cent for the main engine, according to one industry estimate.

“The demand for using rotor sails and other wind-assisted propulsion technologies is growing rapidly,” said Merchant. The market in Asia-Pacific ex-China is projected to grow at a compounded 80 per cent annually from 2023 to 2032, to hit over S$3 billion, he said.

Another retrofit solution Seatrium offers is the modification of a ship’s bow from a pointed edge to a bulbous one. This reduces the drag vessels face from waves and can cut fuel consumption by up to 10 per cent, said Merchant.

Seatrium is also winning work to equip ships with carbon capture and storage (CCS) technologies. The company announced in February it would install a CCS system on a liquefied petroleum gas carrier owned by Norwegian company Solvang.

It’s a bird, it’s a vessel

Beyond retrofitting existing vessels, shipbuilders are working on building vessels that are more energy efficient.

ST Engineering AirX – a joint venture between ST Engineering and Singapore-based startup Peluca – is working on a hovercraft-like vessel that moves at high speeds by skimming the water’s surface.

Called the AirFish, it can achieve 90 knots – thrice the speed of conventional marine craft. Its design is inspired by the albatross, which taps aerodynamic forces to efficiently glide over the water surface.

“The air between the vehicle and water actually forms a cushion and reduces the drag… It needs less power to bring you from point to point, and that’s the reason why it can go very much faster than boats,” said Leon Tan, general manager of ST Engineering AirX.

The AirFish’s fuel consumption is about 30 per cent lower than that of ferries and 20 per cent lower than that of turbo aircraft, on a per-available-seat-kilometre basis. The company is looking into the possibility of the AirFish running on sustainable fuels, such as biofuel, said Tan.

Tests in Singapore will begin from the third quarter of this year. ST Engineering AirX has inked a letter of intent to provide Eurasia Mobility Solutions with AirFish craft for Turkey’s tourism and private transportation sectors.

Other potential markets for the AirFish include South-east Asia and Japan, where there are many small islands, as well as coastal transportation in the United States and Australia, said Tan.

Going hybrid

Electrification is another way shipbuilders are looking to cut fuel usage, although deploying this requires some finesse.

Singapore-listed Penguin International , which builds aluminium high-speed craft, has several hybrid vessels under construction, said its general manager for group commercial and fleet, George Philip.

Hybrid vessels make sense for certain operating profiles, such as if the vessel alternates between high and low speeds, said Philip.

“When you are running at higher speeds, (say) 15 to 20 knots, the battery is also charged. When you are running at lower speeds, say 0 to 5 knots, the batteries kick in and you’re running an electric boat,” he explained.

If the vessel is moving at a high speed all the time, however, a hybrid vessel would burn more fuel than a conventional vessel because of the extra weight.

Philip added that simple design can often generate greater energy savings than complicated technologies. Penguin focuses on keeping the vessel as light as possible, and optimising hull design.

“We work with designers worldwide so that the hull form we have is actually efficient. That itself can save 5 to 10 per cent of the fuel,” said Philip.

Challenges ahead

With plenty of buzz around energy efficiency projects for vessels, Merchant of Seatrium sees demand shaping up to be strong – “especially among ageing fleets seeking to comply with stricter safety and environmental regulations”.

Financing is a challenge, though. While many energy efficiency projects cost under S$10 million, banks are reluctant to fund them. Reasons include the uncertainty of long-term business prospects and challenges in verifying fuel savings.

The financial sector could play a bigger part in helping the shipping industry reduce its emissions. Said Merchant: “Banks should work with shipowners to offer more reasonable loans, and charterers (should) also be involved as they are the direct beneficiary of the retrofits.”