Ship Power Limits Won't Cut CO2 Emissions, IMO Told

IMO Headquarters. Image Credit: Ship & Bunker

Proposals to limit ship power to reduce CO2 emissions will not work, IMO has been told during this week's 6th Session of its Intersessional Working Group on the Reduction of GHG Emissions (ISWG-GHG 6).

Proposals from Japan and BIMCO, backed by the likes of Maersk and Union of Greek Shipowners, suggest that limiting vessel power is superior to limiting vessel speed.

Advocates for power limits say many factors affect vessel speed that are unrelated to the resulting emissions, such as ship design, hull fouling, and weather conditions, and as such speed limits could actually penalize more energy efficient vessels.

But the results of a study presented to IMO yesterday and shared with Ship & Bunker, finds that in the era of slow steaming most vessel operating hours would not be impacted by the proposed engine power limits.

Power limit proposals could therefore "lock-in" current CO2 reductions from slow steaming, but they would not reduce them further as intended.

"Power limitation as a concept has been holed below the waterline. Yesterday's analysis showed it simply doesn't work very well at cutting CO2. Mandatory operational standards are the only way forward now, on either real-world efficiency or real-world speed, take your pick," an IMO delegate said who spoke on condition of anonymity.

The issue is quickly emerging as the latest polarizing debate for the industry, with green groups Monday saying speed limits were the "closest thing to a silver bullet the IMO will ever see", while The UK Chamber of Shipping says simply that speed limits are "not the answer to cutting emissions."