ABB ship electrification system demonstrates efficiency, emission cuts

2014-09-01 - As the “Dina Star” rides the waves off its home port of Bergen, Norway, the ABB system distributing electricity on the platform supply vessel is helping trim the ship's fuel consumption by up to 27 percent.
Myklebusthaug's Dina Star, with ABB's Onboard DC Grid helping save fuel, cut emissions

Thanks to ABB’s Onboard DC Grid, the 94-meter Dina Star has proven itself more efficient than existing ships of its kind. By distributing electricity via direct current, its engines run at the precise speed demanded, whether cruising the open sea or delivering supplies to an oil rig in nasty weather.

For owners of yachts, ferries and tug boats that also operate at varying speeds with ever-changing loads, ABB’s Onboard DC Grid promises significant fuel savings and help meeting ever-stricter emissions limits that threaten to drive operational costs higher.

Eero Lehtovaara, head of ABB’s Marine Design House
“To obtain maximum efficiency in operations, you should have maximum flexibility of your ship,” said Eero Lehtovaara, head of ABB’s Marine Design House. “If you have to react fast with the power plant you have, the Onboard DC Grid gives you really significant advantages with fuel costs.”

A revolutionary idea, a half-decade in the making

What seems clear now – test results by marine engine dealer Pon Power confirmed the Dina Star’s better-than-forecast fuel savings – wasn’t so apparent to ABB engineers embarking on the Onboard DC Grid project a half-decade ago.

The question in 2009 was, where aboard a ship offered the greatest opportunity for improvements in efficiency and reliability, said Klaus Vänskä, ABB Marine technology manager in Helsinki.

The solution emerged after much study, he said: Tackle the ship’s engine, which often operates far below its optimum efficiency because it's running at a constant speed, even when its loading level varies depending on the job it's performing.

By distributing electricity via direct current, however, ABB’s Onboard DC Grid allows ship engines to achieve maximum efficiency by controlling their speed to suit the task at hand. That includes, in particular, dynamic positioning, or DP mode, where platform supply vessels like the Dina Star work next to a drillship or transfer supplies close to an installation.

Onboard DC Grid suited for broad operational profile

“If your operational profile has a quite wide range of the power, like in the DP mode where your power varies a great deal, the Onboard DC Grid offers the biggest benefit,” Vänskä said.

Klaus Vänskä, ABB senior technical advisor
Additional advantages include elimination of power distribution components that accompany traditional AC systems, creating more space on board. And with DC electrification, solar panels, fuel cells or batteries can be more easily integrated, boosting potential for future energy savings and emission reductions.

For ship owners like Myklebusthaug, this helps reduce operating risks and maximize profit.

“We operate in a highly competitive market where customers are increasing their focus on operational costs and environmental impact,” said Tore Myklebusthaug, Myklebusthaug Offshore’s general manager. “The results from Dina Star are promising and enhance our competitive edge."

Team effort

The project demanded a multidisciplinary team of ABB experts, stretching from Finland to Turgi, Switzerland, where technicians installed ABB main generator rectifier and excitation systems, to Ulsteinvik, Norway, home of ABB Marine’s Low Voltage drives.

ABB corporate researchers joined in, too, modeling the Onboard DC Grid with simulations. “The expertise is in house,” Vänskä said. “Smaller companies don’t have corporate research centers that would help you.”

The task wasn’t merely to ensure more efficient electrification, but also to achieve the same safety level of existing AC systems.

Tests show 27 percent reduction of specific fuel consumption aboard the Dina Star
“Safety comes first at sea,” said Ulf U. Ødegaard, an ABB engineer from Norway who worked on the project. “If we couldn’t manage the safety system, we wouldn’t have the Onboard DC Grid.”

The evidence ABB reached its goal? The American Bureau of Shipping and Det Norske Veritas have extended initial approvals, meaning ABB can execute the Onboard DC Grid for prospective shipowners with the same predictability and consistency as with technology covered by existing class rules.

ABB is working with Lloyd’s Register and Bureau Veritas, to further advance the technology’s acceptance by maritime classification societies.

Benefits exceeded expectations

The system’s advantages, however, surpassed even expectations of engineers who worked most intimately on the project. During testing, Dina Star crew noticed something nobody had been counting on: a 30 percent noise reduction.

Running engines at the frequency required for the job means those aboard enjoy a significantly improved working environment.

“It came as an additional benefit we found during the sea trial,” Vänskä said. “It was the owner who realized it, comparing it to the existing vessel he had.”