Evidence is growing that scrubbers work well, save money and do not cause significant pollution, claims a ship operator that has used them for 10 years.

But even as they press the case for exhaust gas cleaning systems, scrubber proponents admit the bigger issue they now face is combating greenhouse gas (GHG) emissions.

Danish ferry operator DFDS presented new evidence from CE Delft that pollution from the use of open-loop scrubbers, which pump wash water into the sea, causes minimal pollution compared with pollution that land-based industries pump into the sea via rivers.