Potential CO₂ reductions under the Energy Efficiency Existing Ship Index

This paper assesses the proposed Energy Efficiency Existing Ship Index’s (EEXI) effectiveness in reducing fuel consumption and carbon dioxide (CO₂) emissions under the International Maritime Organization’s (IMO) greenhouse gas mitigation strategy. The authors model the fuel and CO₂ savings of the EEXI in 2019 and 2030 for container ships, bulk carriers, and oil tankers. These ships produced more than half of CO₂ emissions from international shipping in 2018. The authors find that the EEXI would make only a small contribution to IMO’s climate goals and would reduce CO₂ from the 2030 fleet by just 0.7%. This is because of the continuing prevalence of slow steaming, where most ships are operated at engine loads that would be unaffected by the EEXI standard. In 2019, containers, oil tankers, and bulk carriers were operated on average at between 11 to 14 knots, or between 38% to 50% of their maximum continuous rating (MCR), well below the engine loads allowable under the EEXI. If the EEXI does not limit engine power below what ships now use, it will not result in reductions in ship speed or CO₂. The authors conclude that the main effect of the EEXI would be to codify current operational efficiency gains due to slow steaming. Three areas of improvement are possible: 1) the EEXI could be calculated at a higher load point taking into account an engine’s sea margin; 2) the targets could be implemented as soon as possible and strengthened over time alongside the Energy Efficiency Design Index (EEDI); 3) any override of a ship’s engine power limit should be strictly policed to ensure that it was for safety reasons only. In particular, evaluating the EEXI at 87% of limited MCR would protect against a resurgence in emissions, if improved market conditions lead to a return to faster ship speeds.

• Record URL:
  https://theicct.org/sites/default/files/publications/Marine-EEXI-nov2020.pdf
• 
• Summary URL:
  https://theicct.org/publications/marine-eexi-nov2020
• Corporate Authors:

  International Council on Clean Transportation (ICCT)

  1500 K Street NW, Suite 650
  Washington, DC  United States  20005
• Authors:
  • Rutherford, Dan
  • Mao, Xiaoli
  • Comer, Bryan
• Publication Date: 2020-11

Language

• English

Media Info

• Media Type: Digital/other
• Features: Figures; References; Tables;
• Pagination: 18p
• Serial:
  • Working Paper
  • Issue Number: 2020-27
  • Publisher: International Council on Clean Transportation (ICCT)

Subject/Index Terms

• TRT Terms: Carbon dioxide; Engine efficiency; Exhaust gases; Fuel consumption; Ships; Speed limits; Standards
• Identifier Terms: Energy Efficiency Existing Ship Index (EEXI)
• Subject Areas: Energy; Environment; Marine Transportation;

Filing Info

• Accession Number: 01760957
• Record Type: Publication
• Files: TRIS
• Created Date: Dec 22 2020 9:36AM