Adjust font size:

LONDON, England (CNN) -- Whenever there is a hike in oil prices, the idea of a return to wind-powered shipping catches favor, but sail ship designs have often fallen short on a number of points, not least that they have to rely on unpredictable weather.

However, the future of shipping could feature wind power, but with kites, not sails.

Flying a kite to propel a ship might sound like something from Kevin Costner's cinematic damp swib, "Waterworld", but that is exactly what a number of nautical engineering firms propose.

Sails, no matter how sophisticated their design or use of lightweight modern materials have a fundamental flaw: they take up valuable deck space and storage room that is better used for cargo.

Kites have the advantage of not needing masts, do not need a large area to store them and can be retrofitted to existing ships.

"Kites hold the potential to change the way we move goods across oceans. They are eco-friendly and sufficiently cost effective to herald a return to sail that the Earth's finite petroleum supplies mandate," says Dave Culp, President of California based company KiteShip.

Another company that is throwing itself into towing kite technology is SkySails, based in Hamburg, Germany. The company was founded by Stefan Wrage, who has developed his idea in the face of much scepticism in the past.

Neither company is proposing that engines will be made redundant with the use of a kite, rather that the added propulsion will save a considerable amount in fuel costs.

Earlier this year SkySails trailed a kite on an 800-ton former buoy tender in the Baltic Sea. Using a towing kite of only 80-square-meters the Beufort reached five knots in low winds.

While this doesn't sound very impressive, add to it engine propulsion and Wrage and his team believe that a saving of between ten and 35 percent could be made on fuel costs and in better wind conditions, perhaps even 50 percent.

As with fixed sails, the problem in the past was scheduling wind conditions, but this has been negated by more accurate satellite predictions and long-range forecasts of the weather available to shipping.

SkySails incorporate a computerised system that can plot a ship's course according to the best winds and most cost-effective route. Another key to the successful development of Wrage's idea has been the deployment and steering mechanism.

As anyone who has flown a kite remembers, they aren't always the most predictable and easy things to navigate or keep in the air. If a 200-square-meter kite plummets into the North Atlantic in choppy conditions, there is going to be a problem.

Deployed from a retractable mast on the ship's deck, the kite is controlled by a central console that operates like a plane's autopilot system, monitoring and recording over 100 measurements in fractions of seconds to keep the kite in its optimum position.

Once up, the kite flies at between 100 and 500 meters above sea level where the winds are around 50 percent stronger. In these conditions it's designed to take on the optimum aerofoil shape that ensures that the kite can maximize thrust whatever the conditions.

Shipping has been coming under increased scrutiny from environmentalists for its contribution to climate change. This coupled with the less altruistic desire by shipping companies to save money on fuel makes the new wave of towing kites an attractive possibility.

Recent studies on the environmental effects of shipping have revealed that marine diesel engines have a greater impact than previously thought. As well as releasing nitrogen oxides and damaging PM10 particles into the atmosphere, burning marine diesel oils also contains 2.7 percent sulphur, which is over 500 times the EU's allowed limit for diesel for automobiles.

SkySails believe that if their technology is applied to shipping it could save over 146 million tons of C02 annually. Also working in SkySails' favor is the recent EU legislation reducing the acceptable level of sulphur emissions for shipping.

Wrage is aiming high. The company hopes to equip at least 15 percent of the world's trade fleet of as well as 250 super yachts with its kite technology. One surprising side-effect of their recent tests was the stabilizing effect of the kite when unfurled, a benefit that he believes would attract the cruise liner industry, where a smooth ride for passengers is all important.

While the shipping industry is adjusting itself to a future where it can no longer depend on fossil fuels, many remain cautious and conservative. There are still plenty of doubts over whether SkySails' kites or the latest designs of sailing ships will provide the answer to future fuel problems.

Keeping a weather-eye on the technology is Phil Atkinson , Technical Director of Graig Group Shipping.

"There are a number of other more cost-effective methods to save fuel costs at present, such as improved propeller technology and advanced coating technology for hulls. There are still too many variables involved in both kites and fixed aerofoil sails," he told CNN.

"Also, kites may be good in some areas, but in the Indian Ocean for example where the winds are light, they just wouldn't be practical or cost-effective."

One company that has thrown caution to the wind is Beluga Shipping. It has invested in SkySails and will equip a 140 meter-long cargo freighter with a 160 square meter kite later this year.

"We don't see investing in SkySails as a risk. Reducing emissions from shipping and investing in wind power are key to the future. We expect to gain a 15 to 20 percent reduction of fuel cost from the kite. We've seen the tests and think this is being realistic " a Beluga Group spokesperson told CNN.

The MS Beluga SkySails will be unfurling its kite on its maiden voyage to South American next April.

"We will have to scale up the size of the kite to see a greater reduction in fuel costs, but as an initial additional propulsion system for the ship, we believe it will still be a success."

There will be numerous interested observers when the MS Beluga SkySails leaves port for the first time. As for whether or not more kites will be flown on the high seas, the answer is blowing in the wind.