快猫短视频

A growing number of ships are blowing bubbles beneath their hulls to improve fuel efficiency and reduce greenhouse gas emissions.

鈥淏y adding a layer of air underneath a vessel, you reduce the friction of the hull,鈥� says , co-founder of Marine Performance Systems, a company in the Netherlands that designs such systems.

The idea is known as air lubrication and has been around since the 19th century. But it is only recently that it has attracted interest among commercial shipping operators amidst growing聽pressure to reduce emissions. Shipping is responsible for about 3 per cent of annual global emissions.

Four years ago just had air lubrication systems installed, including cruise ships, natural gas tankers and container ships. Today, 78 large vessels have air lubrication systems and at least 155 are set to be installed over the next few years, according to at Clarksons Research in London, a shipping analytics firm.

Many of those contracts to design and install the systems are with UK-based company Silverstream Technologies. , the company鈥檚 CEO, points to new regulations driving the demand, such as minimum energy efficiency set by the International Maritime Organization. He says air lubrication is also attractive because it is compatible with any type of fuel and, unlike some other green shipping technologies, is ready to go now. The high price of shipping fuel is also a factor.

Air lubrication systems work by injecting microbubbles smaller than two millimetres in diameter into a thin, continuous layer that flows along a ship鈥檚 underside, with different companies varying on how they do this. Marine Performance Systems injects bubbles through narrow bands installed at regular intervals under the ship. Silverstream鈥檚 system involves a series of openings arranged in an arrow along the front of the hull.

Silberschmidt says cruise ships and container ships see around 5 per cent improvement in fuel efficiency from their air lubrication system, while larger tankers see savings of about 8 per cent.

at the University of California, Berkeley, says similar savings have been measured in laboratory and real-world tests on other systems, though the efficiency improvement can drop when bubbles escape on rough seas. He says air lubrication has a role in decarbonising shipping, though the emissions reductions are small compared to more comprehensive changes like powering ships with zero-emission fuels.

M盲kiharju says fuel efficiency could be improved by as much as 16 per cent if air lubrication was used in combination with 鈥溾�� coatings that repel water.

Ship builders in China, Japan and Korea have also started installing air lubrication systems including Hyundai Heavy Industries, Daewoo Shipbuilding & Marine Engineering and Samsung Heavy Industries. Maersk, a major player in shipping, is testing out Silverstream鈥檚 air lubrication system on one ship, and the Mediterranean Shipping Company has ordered systems for around 50 new container ships.

Of the roughly 100,000 large ships in the world, about 20,000 are both big and new enough to be retrofitted with air lubrication and more could be added to new builds, says Silberschmidt. 鈥淲e are expecting air lubrication to become the standard in shipping,鈥� he says.