The International Maritime Organisation is doing what it can to encourage shipping to reduce harmful emissions from shipping.

They want the industry to move to low emission fuels in stages with the adoption of Very Low Sulphur Fuel Oil and to newer minimal emission fuels as they become available.

However, some in the industry want to avoid investment in changing the fuel used by using scrubbers which extract the harmful pollution from the exhaust systems.

The race to install scrubbers only began recently. In January 2020, the IMO – the United Nations body overseeing shipping – announced a new global sulphur cap of 0.5%, reduced from 3.5%. To meet the target, it urged the global shipping fleet to switch to low-sulphur fuel.

But it also allowed for “equivalent” compliance measures, as long as ships reduced their emissions. Scrubbers have proved to be the cheapest way to do so. The cost of buying and fitting a scrubber is £1.5m to £5m, whereas cleaner fuel is £250-£400 a tonne. The scrubber pays for itself within a year.

However, Scrubbers, which sit in the funnels, or exhaust stacks, of ships, use seawater to spray or “scrub” the sulphur dioxide pollutants from the engine’s exhaust. Most vessels use an open-loop system, meaning that instead of holding waste in a tank to be disposed of at dedicated port facilities, the ships directly dump the acidic wash – up to 100,000 times more acidic than seawater – overboard, says Eelco Leemans, an Arctic marine researcher.

Have a read of this thought-provoking article: https://www.theguardian.com/environment/2022/jul/12/shippings-dirty-secret-how-scrubbers-clean-the-air-while-contaminating-the-sea