The technology group Wärtsilä will supply its Volatile Organic Compounds (VOC) recovery technology, LNG fuel gas handling systems and the auxiliary engines for two new shuttle tankers being built for Singapore-based AET Tankers at the Samsung Heavy Industries shipyard in South Korea. The order, worth in total more than €30 million, was booked in January 2018.

The ships will operate on Liquefied Natural Gas (LNG) as the primary fuel, but VOC—the gas evaporating from the oil cargo tanks—will also be utilized as fuel by mixing it with the LNG, thereby reducing the vessels’ bunkering needs. This is made possible by Wärtsilä’s VOC recovery system, which by combining the VOC with the LNG, provides the potential for savings of more than 3000 tons of fuel each year per vessel. This is in addition to the notable environmental benefits the use of gas as fuel provides by enabling a significant reduction in CO₂ emissions.

The recovery of VOC is accomplished by introducing tank vent gas into the VOC recovery system, and then using a condensation process to separate the heavier hydrocarbon fractions of the gas. The lighter hydrocarbon fractions are non-condensable and are fed to a power generating module—i.e., the VOC recovery is 100% and VOC emissions are entirely eliminated.

The separated heavier fractions are liquefied from the VOC unit and stored in a pressurized storage tank. LVOC is a light hydrocarbon fuel that can be utilized as a clean fuel in power generating modules and inert gas generator units. The Wärtsilä VOC recovery system has been successfully utilized onboard several shuttle tankers and floating storage units (FSU) in the North Sea.

Wärtsilä expects the technology for creating a fuel mix of LNG and recovered VOC, both for the 2-stroke main engine as well as the 4-stroke auxiliary engines, to capture the interest of tanker fleet owners around the world. Improved economic and environmental performance is a clear industry target for future operations.

Wärtsilä is once again ahead of the curve with its VOC recovery technology, which was a key consideration in the award of this contract. The fuel savings efficiency of the system enables a fast pay-back time, while the reduction in emissions of CO2 equivalents is as much as 40 percent when compared to conventional solutions.

—Timo Koponen, Vice President, Vice President, Processing Solutions, Wärtsilä Marine Solutions

Wärtsilä’s scope of supply for each of these ships includes the VOC recovery plant, the liquefied VOC fuel tank, the fuel mixing unit, the LNG fuel tank and fuel supply system, the gas valve unit (GVU) and two Wärtsilä 34DF dual-fuel auxiliary engines. The equipment is scheduled for delivery to the yard commencing in the autumn of this year.

The 277-meter, 125,000 DWT tankers will operate mainly for Statoil, the Norwegian state owned energy company, in the North Sea.