As the International Maritime Organization’s (IMO) new rules governing shipping emissions post-2020 approach, shipping operators are weighing their options.
By 1 January 2020, ships must have transitioned to using fuel with a sulphur content of no more than 0.5%, compared to the current limit of 3.5%. The IMO says: ‘Simply put, limiting sulphur oxides [SOx] emissions from ships reduces air pollution and results in a cleaner environment. Reducing SOx also reduces particulate matter, tiny harmful particles which form when fuel is burnt. A study on the human health impacts of SOx emissions from ships, submitted to IMO’s Marine Environment Protection Committee (MEPC) in 2016 by Finland, estimated that by not reducing the SOx limit for ships from 2020, the air pollution from ships would contribute to more than 570,000 additional premature deaths worldwide between 2020 [and] 2025. So a reduction in the limit for sulphur in fuel oil used on board ships will have tangible health benefits, particularly for populations living close to ports and major shipping routes.’
Broadly three potential solutions exist for reducing sulphur emissions in compliance with IMO restrictions: low emission fuel, alternative fuel and emissions scrubbers.
Fuel substitution
Both low sulphur fuel and liquid natural gas – the presumptive substitute for current bunker fuels – present the same issues: transitioning to fuels which are IMO 2020 compliant will raise costs for operators; and ships which switch to a new fuel type could face issues of compatibility affecting wider machinery systems, exacerbated by a lack of overarching standardisation on low sulphur fuel composition.
Emissions scrubbers
Open loop scrubbers in particular have been the subject of extensive debate with regard to IMO 2020 compliance – while they reduce the sulphur output of existing shipping fuels, the wastewater discharged as a byproduct of the scrubbing process is pumped into the ocean, contributing to marine pollution. This has led a number of port authorities and marine environment advocates to call for a ban; which industry representatives have strongly opposed on the basis that the contribution of scrubbers to reducing sulphur emissions outweighs their potential impact on ocean water quality.
