Solvang meets Tier III targets operating on HSFO

The <i>Clipper Enyo</i>, one of Solvang's four new HFO-fuelled Tier III compliant ethylene carriers. (Credit: Solvang) The Clipper Enyo, one of Solvang's four new HFO-fuelled Tier III compliant ethylene carriers. (Credit: Solvang)

After three years of testing, Stavanger-based shipowner Solvang has received global Tier III certification for its four new ethylene carriers. The carriers operate on high sulphur fuel oil but meets stringent environmental standards.

Earlier in 2019, Stavanger-based shipowner Solvang ASA received type approval for its engine type installed on four new ethylene carriers. The innovation has been verified by Norwegian scientists at SINTEF as well as DNV GL, proving that high sulphur fuel oil (HSFO) operations can continue in Tier III emission areas.

The new vessels have a hybrid exhaust gas cleaning system combined with a low pressure EGR (Exhaust Gas Recirculation) system. The scrubber is tuned to feed the EGR system with optimal exhaust gas for combustion. The scrubber reduced the exhaust gas SOx content from 3.5% to less than 0.1%.

While sustaining more than 80 percent of the world´s ocean freight, HSFO has silently transformed from its polluting past to become the flagship of 2019 green shipping - generating close to zero harmful emissions. The ensuing scope for global shipping’s contribution to combatting climate change can´t be overstated, according to the scientists and members of the shipping community.

The solution combines the benefits of operating on a non-distillate bunker, which used correctly can keep emissions far below the 0.5 % sulphur threshold, with the possibility for shipping to exceed its Tier III NOx obligations. In addition, the vessel benefits from a tried and tested fuel, which offers certain opex advantages over lower sulphur alternatives, such as MGO.

Open-loop system

Since 2015, Norwegian shipowner Solvang has developed and tested an open-loop scrubber with washwater cleaning, in combination with low-pressure exhaust gas recirculation (EGR). The setup is onboard Clipper Harald, an ethylene carrier fuelled by non-distillate HFO. The state-sponsored project (Smart Maritime) involved renowned marine scientists from the SINTEF research institute, engine manufacturer and scrubber manufacturer in third-party analyses. In addition to this test ship, five vessels have installed the same type of scrubber and have recorded several thousand hours of service on various engine loads.

Scrubber washwater results

The results of the Solvang/Smart Maritime project showed that scrubber washwater was non-toxic regarding all 35 measured components. Among them, polycyclic aromatic hydrocarbons (PAHs) stood at 10 percent of the official limit, nitrates close to zero, while turbidity was kept safely within the strictest IMO limits. Specific PAHs like fenantren, fluoranten and pyren were higher than in good quality seawater but far below poor quality. Another important finding was that proper sample procedures are crucial to achieve representative results. Previous studies have shown diverging results due to lack of standardized procedures for sampling. Regarding sulphur emissions from HFO, this component is converted to sea salt and fully neutralized.

Nickel and vanadium 

Even though Solvang´s scrubber and EGR setup proves compliant with IMO emission regulations globally and locally, nickel and vanadium might pose a challenge. Vanadium is a natural part of sea water in non-toxic concentrations from 0.9 to 3.5 µg/l (micrograms per litre). The source of vanadium is bedrocks releasing the metal into seawater through erosion. If HFO fuels shipping at the same rate as today, the concentration of vanadium will increase by less than 0.1 percent over a hundred years of operation. In other words, non-significant.

Like vanadium, nickel separates naturally from bedrocks into seawater, which contains nickel in average amounts of 1.7 µg/l. Given that heavy fuel oil contains 50 mg nickel/kg, discharges through another hundred years would increase global nickel concentrations in the range of 0.05 percent.

Solvang have made considerable investments in terms of time and effort based on their belief that shipowners should not be asking themselves which fuel they use, but rather how they handle the fuel and convert it into propulsion. The overall environmental footprint is given by the type of fuel, engine type and operation profile/maintenance and exhaust gas after treatment. Ship owners therefore have a new alternative method to keep their HSFO engines running; add a scrubber with washwater treatment plus a low-pressure exhaust gas recirculation unit. This will make operation IMO-compliant and competitive when approaching the new sulphur cap and Tier III NOx regulations.


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