Scrubbers to be scrubbed?

WASHWATER discharges from open-loop Exhaust Gas Cleaning Systems (EGCS) technology will worsen the accumulation of carcinogens in marine environments, according to Senior Researcher, Marine Program for The International Council on Clean Transportation (ICCT) Bryan Comer.

Countering the findings of a recently released CE Delft report which contends the impact of the technology would be “minimal” on the environment (CW 28 Jan), Comer believes the evidence suggests increased use of open-loop scrubbers in the cruise sector would result in more polycyclic aromatic hydrocarbons and heavy metals in the water, in the sediment, and in marine life.

“As more ships use scrubbers to comply with fuel sulphur regulations, the risk to aquatic ecosystems, wildlife, and by extension humans will grow,” Comer said.

Open-loop EGCS utilise seawater to scrub the exhaust and the resultant washwater is then often mixed with fresh seawater before being discharged into the sea.

Despite cruise ship operators increasingly turning to scrubbers to help meet new emissions targets, Comer told Cruise Weekly the industry should instead focus on investing in the transition to fossil-free, zeroemission propulsion.

“Solutions include energy-saving tech such as hull air lubrication, and wind-assisted propulsion, as well as battery-hybrid propulsion, hydrogen fuel cells, & perhaps ammonia,” he argued.

Comer also took aim at the cruise sector’s uptake of LNG fuels, concurring with Viking Chairman Torstein Hagen’s scathing assessment last week while in Los Angeles in the United States (CW 24 Jan), that LNG engines can leak “high amounts” of unburned methane.

“This technology emitted 70% to 82% more lifecycle greenhouse gasses compared to marine gas oil, this engine type is especially popular for new cruise ship designs,” Comer said.

“We conclude that there is no short-term climate benefit from using LNG, regardless of the engine technology, after taking into account upstream emissions.

“This makes it unlikely to contribute to the International Maritime Organization’s goal to cut greenhouse gas emissions at least in half by 2050,” he added.