Embodied energy trade: Efficiency and losses

Why shipping costs almost nothing next to the energy inside

What this tab covers How much energy is lost while it moves and while it waits in storage or transit, and how much energy the transport itself consumes, in per cent.

Shipping an energy-intensive product costs little energy compared with what it embodies: moving a tonne of aluminium 10,000 km by bulk carrier uses about 0.3 to 0.6% of its total embodied primary energy, or about 1.3 to 2% of its smelting electricity (calculated). The bigger losses are in conversion (ammonia synthesis, cracking) and, for food, in waste.

Chart: Efficiency ranges

Used to drive transport Whole chain Lost while held Lost in transit

Losses by measure

Measure	Range	Type	What is measured
Bulk carrier energy to move aluminium 10,000 km	0.3 to 0.6%⁶²⁰³	Used to drive transport	Ship fuel as a share of 186 GJ per tonne embodied primary energy (calculated; 1.3 to 2.0% of the 51 GJ of smelting electricity alone). Uses IMO 2022 median EEOI of 9.1 to 14.9 g CO2 per tonne-nautical mile for 10,000 to 99,999 dwt bulk carriers, 3.114 t CO2 and 40.2 GJ per tonne of fuel oil, giving about 0.06 to 0.10 MJ per tonne-km
Ammonia synthesis energy	12 to 26%⁷	Whole chain	Energy used to make ammonia as a share of the hydrogen energy
Cracking ammonia back to hydrogen	13 to 34%⁷	Whole chain	Energy used at destination as a share of hydrogen energy; avoided if ammonia is used directly
Agrifood energy tied to food loss and waste	38%¹²	Lost while held	Share of energy consumed in agrifood systems that is embodied in food lost or wasted (FAO, 2014 estimate)
Light pipe, 12 m run, 99.7% reflective tube (manufacturer data)	89%¹⁶	Lost in transit	Share of entering daylight delivered after 40 ft (14% with 95% enhanced aluminium)
Fuel saved by wind-assisted propulsion	5 to 20%¹⁵	Used to drive transport	Typical reported fuel saving from retrofitted systems; newbuilds may save more

Holding periods and inventory

Measure	Value
Volume shipped, green iron versus inputs	HBI for a 2.5 Mt a year plant needs 0.75 to 1 million cubic metres of cargo, under a third of the 3.5 million for ore plus hydrogen¹⁰
Holding losses of metal and ammonia	Metals do not lose embodied energy in storage; HBI must be kept dry to avoid re-oxidation¹⁰
Data transmission energy	Networks used 260 to 360 TWh in 2022, similar to data centres; fixed-line energy per unit of data has halved about every two years¹³

Food is the exception to cheap embodied transport: about 70% of agrifood energy is used after the farm gate (transport, processing, packaging, storage, marketing), and much of it ends in food that is lost or wasted. For data, sending results is cheap per job, but networks as a whole used 260 to 360 TWh in 2022, comparable with data centres. The shipping figure is sensitive to ship size and route: small bulk carriers and containerships use more fuel per tonne-km than large bulkers.

Sources

Factsheet: Aluminium smelting with use of low-carbon electricity GIZ (Deutsche Gesellschaft für Internationale Zusammenarbeit), 2025
Report on annual carbon intensity and efficiency of the existing fleet, reporting years 2019-2022 (MEPC 81/6/1) International Maritime Organization, 2023
Global Hydrogen Trade to Meet the 1.5 C Climate Goal: Technology Review of Hydrogen Carriers IRENA, 2022
SteelWatch explainer: why green iron trade will catalyse steel industry decarbonisation SteelWatch, 2025
Energy: facts and figures FAO, 2025
Data Centres and Data Transmission Networks IEA, 2023
Wind-assisted propulsion fleet crosses 100-vessel mark (International Windship Association data) Engine Online, 2026
Daylighting Fact Sheet (company data) Solatube, 2013
Aluminium recycling saves 95% of the energy needed for primary aluminium production International Aluminium Institute, 2021