快猫短视频

LIKE the clippers of old, the cargo ships of tomorrow may one day raise sails, though with a modern twist. They might also sport solar panels, and even glide through the ocean on cushions of air.

Typical cargo ships today are little different from their forbears a century ago: dirty, oil-burning behemoths. Because of their huge size, they鈥檙e an efficient way to move goods, but the industry is so vast that the amount of carbon they emit exceeds that of all the world鈥檚 aircraft. If the global fleet were a single country, its emissions would rank seventh in the world (see graph).

Now the realities of volatile oil prices, climate change and pollution are setting in, and ship-builders are changing their tune.

鈥淢ining companies are telling us that to ship a tonne of iron ore, something like 90 per cent of the cost is fuel,鈥� says Robert Dane, CEO of Solar Sailor in Sydney, Australia, which makes ships that are powered by a combination of combustion engines and solar power. What鈥檚 more, under mounting public pressure, the International Maritime Organization that ships increase their fuel efficiency and reduce emissions of carbon and other pollutants by 25 to 30 per cent by 2030.

Dane thinks an ore carrier could achieve up to 20 per cent savings in fuel costs using large solar panel-covered masts that both charge a battery and catch the breeze. Eco Marine, based Fukuoka, Japan, is using a similar approach, and expects to test its first prototypes in 2012.

Such solutions are meant for the largest bulk carriers, such as Panamax and Capesize-class vessels, which can carry tens of thousands of tonnes of cargo. But to green up the legions of smaller ships that move goods along coastal shipping lanes, UK firm B9 Energy Group has brought back the old days of three-masted sailing ships 鈥� with a difference.

The company鈥檚 design employs a Rolls-Royce engine that it can refit to run on natural gas or biofuel. The majority of their ships鈥� propulsion, though, will come from giant sails. These will be able to unfurl or fold up at the push of a button, avoiding the need for the large crews that manned the rigging of large sailing ships in years gone by.

Meanwhile, some firms are saving fuel in a decidedly low-tech fashion 鈥� they are slowing down. In 2008 as oil prices shot up to $145 per barrel, shipping giant Maersk cut fuel use by as much as 30 per cent by slowing down to just 12 knots instead of a full-throttle 25 knots (46 kilometres per hour). Other companies have followed suit; slow steaming reduces friction and increases energy efficiency much as driving a car at 90 km/h can use less fuel than driving at higher speeds.

A more impressive way to glide through the water is to inject air around the submerged part of the ship鈥檚 hull. DK Group in the Netherlands has tested what it calls the 鈥渁ir cavity system鈥�, which pumps air out of a hole in the hull that then travels as a carpet of bubbles under the vessel (see diagram, and 快猫短视频, 18聽February 2006, p聽46).

鈥淎 more impressive way to glide through the water is to inject air around the submerged hull鈥�

Sea creatures such as barnacles and mussels that attach to ship hulls can push up fuel use by as much as 40 per cent. To combat this, paint and coatings firm AkzoNobel, also in the Netherlands, has developed a polymer that forms a microscopic 鈥渃hequerboard鈥� of water-repelling and water-attracting molecules. This makes it much harder for anything to stick, and the company is working on commercialising the technology.

This kind of innovation comes along whenever there is major pressure on an industry, says David Surplus of B9. 鈥淪hippers weren鈥檛 concerned about energy efficiency until now,鈥� he says, as oil prices continue to hover around $100 a barrel, and carbon emissions continue to increase global warming.