8/15/2023 0 Comments Aer meaning latin![]() ![]() You might be thinking: If we have the choice, why wouldn’t we go with the EEOI over the AER? Two reasons. The AER is a “supply-based” efficiency metric, a measure of the theoretical carbon intensity of the fleet because it divides the amount of CO 2 a ship emits by its cargo carrying capacity (deadweight tonnes, or dwt), no matter how full the ship is, and then again by the nautical miles the ship traveled in a year (gCO 2/dwt-nm). What makes the two measures so different? The EEOI is a “demand-based” efficiency metric, a measure of the real-world carbon intensity of the fleet because it estimates how much carbon dioxide (CO 2) was emitted to transport 1 tonne of cargo 1 nautical mile (gCO 2/t-nm). International shipping CO 2 emissions (million tonnes) from 2018 to 2030 and associated annual reductions in carbon intensity (gCO 2/dwt-nm) required to achieve various policy objectives. The table at the end of this post has details of the methodology.įigure. ![]() And yet more ambitious carbon intensity reductions are needed to be aligned with the Paris Agreement.Īs shown in the figure below, greater emissions reductions can be achieved if IMO chooses annual reductions in carbon intensity that are aligned with its 2050 emissions target, -4% per year, or that are aligned with its commitment to the Paris Agreement’s temperature goals, -6% to -7% per year to be 1.5☌ aligned. On the other hand, achieving a 40% reduction based on AER requires a 2% annual reduction in carbon intensity and could cut emissions by 3% from 2018 levels by the end of the decade. In this context the carbon intensity choice matters a great deal, because our analysis shows that achieving the bare minimum 40% reduction based on EEOI could allow emissions to grow 13% this decade, despite a 1% annual reduction in carbon intensity. IMO’s GHG strategy also aims to pursue efforts to phase out emissions on a pathway consistent with Paris Agreement temperature goals, which would include efforts to limit warming to no more than 1.5☌. Then they’ll need to agree on how quickly to reduce the carbon intensity of the fleet. On that last part, the IMO hasn’t yet defined “carbon intensity,” and at the 8th meeting of IMO’s GHG intersessional working group next week, member states will pick one of two competing ways to measure it: the energy efficiency operational indicator (EEOI) or the annual efficiency ratio (AER). The International Maritime Organization’s (IMO) initial greenhouse gas (GHG) strategy calls for emissions to peak as soon as possible, to fall at least 50% by 2050 compared to 2008, and for at least a 40% reduction in the carbon intensity of international shipping by 2030 relative to 2008. For more information, please see the “BAU” row in the table at the end of the updated blog post here. This blog was revised on 21 May, 2021 to correct an apparent error in the business as usual carbon intensity improvement from 2018 to 2030 reported by the Fourth IMO Greenhouse Gas Study, which we estimate should be a 17% improvement from 2018 to 2030 (43% improvement relative to 2008), rather than a 10% improvement from 2018 to 2030 (39% improvement relative to 2008).
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