Vessel emissions rival plastic waste as an environmental hazard to marine environments

In addition to the problems identified with rising levels of plastic waste in our oceans, vessel emissions have now become an environmental issue of equal impact and the rules are changing rapidly.

In 2020, a new air pollution cap on sulphur emissions from the combustion of ship bunker fuel will come into force. This has been imposed by the International Maritime Organisation (IMO). The IMO are forcing vessels to reduce air pollution by using cleaner fuel with a lower sulphur content of less than 0.5%, compared to 3.5% as commonly used at present.

The anticipated cost of buying cleaner, more expensive fuel, that meets the 0.5% limit will typically be between $300 and $500 more per tonne. The Guardian newspaper has seen industry analysis predicting that between 2,300 and 4,500 ships are likely to install a scrubber (an onboard exhaust gas cleaning system) as a means of meeting the 0.5% limit, whilst burning fuel with a sulphur content of >0.5%. The cost of these scrubber systems however is still very high.

The open-loop scrubber system

A scrubber (as the title suggests) washes the exhaust gas onboard the vessel.

The most commonly used system, referred to as open-loop, discharges waste water directly into the ocean. Scrubbers allow operators to continue buying cheaper high-sulphur fuel, and industry analysis predicts that the $2-4 million cost of fitting each open-loop system to a ship would be recovered within the first twelve months of use.

Most scrubbers that have already been fitted are of the open-loop variety. The more expensive closed-loop systems require waste water to be stored onboard a vessel and then disposed of at a facility onshore.

Ned Molloy, an independent shipping consultant explained:
‘Scrubbers’ were allowed by the IMO as a way to meet the lower-sulphur emissions rules, they were little more than an environmental dodge. This is just sulphurous waste going into the sea, it would be illegal to dump this on land anywhere in the EU, except in specialist facilities. There is growing concern, particularly in EU countries, about whether open-loop scrubbers should be allowed.

The possible impact of a rising demand for scrubbers

The possibility of a huge demand for scrubbers to meet the 2020 sulphur cap has raised concerns that the impact on the marine environment has not been fully considered. Some national governments prohibit the discharge of waste water within their ports. Waste water includes particulate matter, sulphur and metals such as lead, nickel and zinc. United Nations advisers for marine environmental protection have warned of a potential increased risk and possible unintended consequences to the marine aquatic environment if this continues.

The IMO 0.5% limit (confirmed in October 2018) included an amendment that actually allows for the use of scrubbers to meet emission restrictions. However, the IMO is reviewing guidelines on the use of scrubbers as countries including the UK, Germany and the Netherlands want improved sampling so that the environmental impact of discharged waste water is better understood.

All in all, the situation is still fluid and would suggest that vessel owners may still encounter further regulatory changes that could void previous capital expenditure decisions, and necessitate further expenditure, to comply with new regulations. This is a situation which could be very difficult to manage in the current tight market environment.