Shipowners who bought exhaust gas scrubbers to meet IMO 2020 guidelines share one sentiment: they proved difficult to install on their ships.

About 50 owners fitted more than 4,000 of the devices— at a cost of at least $2m each — to capitalise on a fuel-price spread between compliant and non-compliant fuels.

They took their vessels out of service for weeks during installations, expecting to make a savings by burning high-sulphur fuel oil for at least $300 per metric tonne less than low-sulphur fuel oil.