Solar ship takes to the seas

World’s first PV-powered container ship launched

When the car container ship Auriga Leader chugged into the Californian port of Long Beach, it was greeted with a torrent of positive press reports – as the first freighter to be partially powered by the sun.

The Auriga, which can carry 6,400 vehicles and makes bi-weekly trips from Japan to California, has an impressive array of 328 photovoltaic (PV) panels stationed on its top deck. The panels – connected to the 440V onboard electricity grid – represent an investment of around $1.7 million for ship owners Nippon Yusen Kaisha and Nippon Oil.

The panels are touted to have a peak capacity of 40kW, when conditions are optimum (think sunny days at high noon) and the ship is docked. This will cover about 0.3% of the engine’s energy requirements, and 7% of other power appliances, such as pumps and lighting. It is estimated that the PV system will save a total of 13 tonnes of fuel over one year – reducing CO2 emissions by up to 40 tonnes.

Surprisingly, the panels have generated 1.4 times more electricity at sea than on land, leading to suggestions that the cool sea breeze improves efficiency.

With the sector’s fuel costs and carbon emissions increasingly under the spotlight, there has been a flurry of activity investigating alternative power systems for shipping. They include the cargo ship MS Beluga’s Sky Sail – a kite towing-system – and Solar Sailor’s hybrid solar/wind power solutions, as well as simple solar arrays as on the Auriga. But none comes cheap. The ‘small bang, big bucks’ is hard to justify in an era when fuel prices are not quite high enough, and the economy not quite strong enough, to make a solid business case for investment.

But Christer Ågren at Sweden’s Air Pollution & Climate Secretariat, who has much experience in the maritime industry, is loathe to pour cold water on any renewable technologies that reduce the fuel consumption of ships: “Solar cells, kites… all these are good – and the more popular they become, the more they’ll be used,” he says. However, Ågren adds that the most cost-effective, money and pollution-saving measure container ships can take is simply to slow down.

“It is incredible, but a 10% reduction in speed equals about a 20% reduction in fuel use,” says Ågren. It’s an approach already adopted by shipping lines such as Maersk when fuel prices are high. But the complexities of docking systems means most ship owners still want their cargo to reach port as quickly as possible.

As yet, shipping has managed to stay outside international emissions reduction frameworks, although research by BP and the Institute for Physics and Atmosphere suggests that the sector’s annual emissions make up 5% of the global total – around twice that of aviation. And according to the International Maritime Organisation (IMO), a business-as-usual scenario would see these more than double by 2050.

Responding to growing pressure from the EU, the IMO advocates a range of what it terms ‘cost-effective’ measures including speed reductions, Beluga-style towing kites, upgrades to hulls, engines and propellers, and policy instruments such as emissions trading and a fuel tax. Taken together, says the IMO, ships could cut their emissions by 75% by 2050. – April Streeter

29 October 2009

April Streeter