UMAS: Efficiency is key to aligning maritime transport at 1.5ºC in 2030


UMAS (University Maritime Advisory Services) released a report earlier this week looking at how unlocking much greater efficiency improvement is key to aligning shipping to 1.5ºC by 2030.

Taking into account the expected growth in demand for international shipping, the report considers four scenarios with relatively low levels of fuel substitution by 2030, and then derives from them fuel substitution scenarios that represent the amount of energy efficiency improvement. needed to reach the 37% target. absolute reduction in life cycle emissions by 2030 (based on 2008 baseline).

According to UMAS, aligning the international shipping ambition level with 1.5°C requires a significant reduction in absolute greenhouse gas (GHG) emissions by 2030 and 2040: reductions of 37% and 96% respectively relative to 2008. Efficiency improvements reduce energy demand and, in turn, make the transition away from fossil fuels easier.

Achieving these reductions requires the parallel activities of maximizing energy efficiency and moving away from the use of fossil fuels in international shipping. Both steps are necessary for both the existing fleet and new ships built during this period.

The 2040 goal depends on the expansion of new energy supply chains in the coming decades, so it is important to develop these supply chains and encourage the use of new fuels in ships in this decade. However, given the short timeframe between now and 2030, new energy supply chains are unlikely to play a major role in achieving 2030 ambitions aligned with 1.5°C; therefore, the role of energy efficiency is key in the short term.

Three options are identified that should result in GHG emissions aligned to 1.5°C by 2030

Option 1: Focus only on short-term measures (e.g. existing Carbon Intensity Indicator (CII) and Existing Ship Energy Index (EEXI) measures), and no need for medium-term measures term (eg, future new policies, such as carbon pricing and/or fuel standards). Short-term measures need to modify WtW GHG emissions, require a reduction of 12% per year (p.a.) from 2027 for the International Maritime Organization (IMO) CII.

Option 2: Focus short-term measures on energy efficiency improvements (to achieve an average efficiency improvement of 38% between 2019 and 2030), and focus medium-term measures on switching fuels that reduce the GHG intensity of the fuel ~15% by 2030. Requires 9% annual reduction starting in 2027 for CII.

Option 3: Focus short-term measures on energy efficiency improvements and medium-term measures on fuel switching, but using regional regulation and voluntary initiatives to drive compliance beyond IMO thresholds (eg example, the fleet average CII moves to band ‘A’). Requires a reduction of 4.5% p.a. from 2027 for CII.

Energy efficiency: the story up to date

In the 2008-2018 period, large GHG intensity reductions were achieved (32% less intensity using the EEOI, ship-based allowance), primarily due to reductions of speed and changes in fleet composition (MEPC 79/INF. 29). The 2018-2022 period has been turbulent in terms of ship operation with COVID-19 and supply chain disruption has caused fluctuations in GHG intensity and, in some cases, speed increases, reversing reductions of GHG intensity.

The composition of the fleet has continued to change, with larger and more technically efficient ships offering continued scope for sustained GHG intensity reductions, even if the turbulence meant that not all of this has yet crystallized in practice.

Cumulative change since January 2012 in CO2 emissions intensity and contribution of container ship size change, grams per ton-mile:

Fuel transition: scale at place

The analysis in MEPC 79/INF.29 shows that any deep decarbonization of international shipping depends on the large-scale adoption of scalable, zero-emission hydrogen-derived fuels (including green ammonia and methanol), with a fleet capable of operate with these fuels.

The finding modeled in that paper is that ammonia is the lowest cost solution for international shipping and dominates the fuel mix by 2040 in all 1.5°C aligned scenarios.

Comparison between potential industry growth rates (as of 2025, shaded regions), current and planned capacity (bars), and projected demand for the ammonia industry (dotted lines):

However, the modeling framework in MEPC 79/INF.29 was constrained by operational CO2 emissions (tank to wake – TtW), resulting in a consequent large growth in LNG use in the short term (prior to 2030) with significant WtW. GHG emissions in the period up to 2030, in relation to business as usual (BAU) scenarios. Therefore, the scenarios do not evidence the feasibility of a 1.5°C aligned WtW GHG 2030 target.

Aligning to 1,5 °C para 2030

Therefore, understanding the feasibility of that goal depends on the answers to the following key questions:

  • How much of the fuel transition could happen by 2030, and what will this mean in terms of a fuel mix?
  • How much energy efficiency improvement is required to achieve overall life cycle GHG reduction?
  • How could such an improvement in energy efficiency be achieved in practice?

What needs to change in the supply chain for LNG, biofuels and hydrogen-derived fuels?


No changes required. The supply chain is being developed under BAU for the required volumes.


Supply chains need stimulation to increase current volumes.

Hydrogen-derived fuel

These fuel options require significant stimulation and development and will take time to develop given their relative immaturity (especially ammonia and hydrogen).

What needs to change in the shipping energy efficiency supply chain?

Slow sailing and virtual arrival
bigger ships
wind assist
Maximum adoption of other energy efficient technologies
three ways to go

Option 1: establish only short-term measures (without dependence on medium-term measures)

Amend existing measures to act on WtW GHG reduction to achieve a 65% reduction by 2030 vs. 2008
Establish the rigor and compliance of CII in a 12% annual reduction of

Option 2: establish short-term measures and medium-term measures

Existing measures are focused on improving energy efficiency and achieving a further 38% improvement on the 2018 efficiency level by 2030.
This option requires the rigor and application of the IIC to a 9% annual reduction of
Medium-term measures focused on achieving bioenergy and hydrogen-derived energy substitution that reduce WtW GHG emissions ~15% for

Option 3: establish short-term measures and medium-term measures that are enhanced by regional regulation and voluntary initiatives

Existing measures focus on improving energy efficiency, medium-term measures encourage fuel transition.
Regional regulation and voluntary initiatives drive average fleet performance to CII ‘A’ rating and improve fuel switching above IMO regulation levels, reducing WtW GHG emissions ~15% by 2030, achieving an additional 38% improvement in efficiency from 2018 requires rigor from the IIC and application of a 5% annual reduction starting in 2027.

view full report: UMAS-How-can-international-shipping-align-with-1.5-C-2023_04

Source: Safety4Sea

Source Safety4Sea

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