Finding a sustainable solution to auxiliary propulsion

Most of us are now familiar with the concept of hybrid cars, where an auxiliary electric motor provides low speed propulsion, with the main petrol or diesel switched off. With the internal combustion engine running, the auxiliary electric motor can provide turbo-like additional power at higher speeds, or increased traction in slippery conditions.

Now WE Tech Solutions Oy of Finland, has applied the same recipe to tankers. The result is a hybrid propulsion system providing an efficient power distribution for marine vessels and tankers. WE Tech claims to be lead provider of hybrid solutions in this sector.

According to WE Tech, the variable frequency WE Drive provides ships with unmatched options in electrical power generation. “Our main five solutions focus on shaft generator applications for four-stroke and two-stroke main engines that use a permanent magnet shaft generator,” explained Mr Mårten Storbacka, the managing director of WE Tech Solutions. “Our solutions provide ship owners with the option to use flexible hybrid propulsion systems that include Power Take Out (PTO), Power Take In (PTI), Boost Modes, as well as efficient power distribution.”

Multi-mode solutions

The multi-mode approach provides a range of solutions. The PTI system ensures a safe return to port (aka take-me-home mode) using auxiliary propulsion drive when the main engine is out of commission. Similar to the use of electric motors in hybrid SUVs, the hybrid system can provide auxiliary power to the main engine when sailing in demanding conditions, such as ice-navigation, or provide an additional power boost for the main engine optimised for low load conditions.

A key feature is the common DC-link, that eliminates traditional design limitations that hinder high levels of efficiency in the distribution of electrical power.

Further, the option of a shore-to-ship power connection, or alternative maritime power (also known as ‘cold ironing’ in the cruise industry) from on-shore generated power, can typically save 50% of power costs, compared to power which is generated on-board the vessel, according to WE Tech.

Solution applied to LNG-fuelled product tankers

It is not just conventional internal combustion engined vessels that can benefit from the addition of a hybrid propulsion system. WE Tech’s solutions have been fitted to a series of four LNG-fuelled product tankers owned by Terntank Rederi AS. These vessels have the option of PTO, as well as PTI in take-me-home mode.

“WE Tech’s shaft generator solution is working well,” says Tryggve Möller, chairman of the board of Terntank Rederi AS and managing director of Terntank Ship Management AB, adding: “Terntank has set huge expectations on this technology and believes this will be the future for the shipping industry”. According to WE Tech, the system increases the vessel’s energy efficiency by 20%-30% compared to those without such a system. Therefore, fuel consumption and operational costs are reduced, by the order of hundreds, if not thousands of dollars per vessel per day.

“In each case, we look for ways to improve energy efficiencies and increase the vessel’s competitiveness,” said Mr. Storbacka. “This is becoming more critical, as maritime vessels strive for innovative ways to be more efficient with their fuel consumption.”

With WE Tech’s Energy Storage Solution, the battery-based solution provides an energy reserve, used for electrical load peak shaving and providing energy for black-out prevention. “We have seen increasing demand for Energy Storage Solution in the marine industry,” says WE Tech Solutions’ sales manager, Mr Martin Andtfolk. “Our Lithium-ion battery-based solution can easily be added to our other solutions. This makes vessel-based electric power generation even more efficient and cost-effective.”

Chemical tanker fitment

In January 2017, WE Tech delivered a hybrid solution to two 17,500 dwt chemical tankers belonging to the Norwegian Shipowner, Rederiet Stenersen AS. Commenting on the implementation, Rederiet Stenersen’s Director Ship Management, John Stenersen said: “At Stenersen, we take pride in being at the forefront of achieving the best energy efficiency in our segment. As far as we are aware, Stenersen is the first company to have installed such equipment on this type of vessel. We believe that energy storage solutions will contribute to a stronger market position for Stenersen, through sustainable competitive advantage. This is a catalyst for other companies to commit to ‘greener technology’ for the future.”

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