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Explora: Environment
and Resource WTW emissions of road, rail, sea, and air transport

For freight transport between Brisbane and Melbourne pronounced; the emissions intensity for air transport was,
by sea, the average emission intensities for container ships on average, 96 – 265 times higher with non-CO effects.
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on the route (9 – 16 g CO -e/tkm, depending on the year) Compared with the other transport modes, the plausible
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were approximately twice as high as those for bulk carriers range in emissions performance for air freight transport
(4 – 8 g CO -e/tkm). Stationary (at berth) conditions was also very large, reflecting the variability and uncertainty
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contributed significantly to total trip emissions. Currents in aircraft emissions. This itself was an important
reduced or increased FC (and emissions) by about 2 – 4% outcome from the study and is relevant information for
for container ships and 4 – 6% for bulk carriers. For both policymakers and planners: not only does air transport
types of ships, the emission intensity was approximately have the highest mean emission intensity but it also has
halved between 2019 and 2050. the largest uncertainty in emissions performance. This
Excluding non-CO effects, the emission intensity of air means that actual emissions can be substantially lower or
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passenger transport decreased from 166 g CO -e/pkm in higher than the average values. Air transport is a highly
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2019 to 89 g CO -e/pkm in 2050. For air freight transport, carbon-intensive transport mode for freight and is clearly
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the emission intensity decreased from 1,345 g CO -e/ distinguishable from the other transport modes.
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tkm in 2019 to 719 g CO -e/tkm in 2050. The average While sea and air transport are expected to show a
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emission intensities with non-CO effects were a factor gradual decline in GHG emissions, land transport shows
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of 1.8 higher than the values without these effects. The a more non-linear trajectory. Road transport is expected
simulations showed that typically around 65% of total FC to significantly improve its performance after 2030 when
(and emissions) during a flight occurred during cruise, zero- and low-emission vehicles start to penetrate the
25% between take-off and cruise, 5% between cruise and on-road fleet at an accelerated rate. In contrast, electric
landing, and 5% during taxiing. rail is decarbonizing much faster, in line with the
For passenger transport, aircraft generally had the decarbonization of the electricity grid. This is an additional
highest emission intensity of all modes. When non-CO important benefit of electric rail over the other transport
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effects were included, the emission intensity of air modes.
transport was 1.7 – 2.8 times higher than that of road For passenger transport between Brisbane and
transport. High-speed electric rail may be a more practical Melbourne, the complete transfer of travel from air
alternative to air transport for inter-capital travel. The to electric rail would reduce annual WTW emissions
emission intensity of air transport was up to 25 times (including non-CO climate effects) by around 95% in
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higher than that for electric rail. The uncertainty in the both 2030 and 2050. The complete transfer from air to
WTW emission intensity was also highest for air passenger road, were it to be practical, would reduce emissions by
transport. This is relevant information for policy-makers 32% in 2030 and 58% in 2050. For freight transport in
and planners; not only does air passenger transport have 2030 and 2050, bulk carriers and electric rail were the most
the highest mean emission intensity of all modes but there efficient modes of freight transport, followed by container
is also a high level of uncertainty regarding its emissions ships. Air transport was by far the least efficient, and the
performance. highest emitting. From this perspective, it is beneficial that
For freight transport, ships generally performed very little domestic freight in Australia is currently being
significantly better than the other modes. Compared with transported by air.
road freight, sea freight had an emission intensity that was Realistic and effective mode shifts to reduce WTW
around 85% lower for bulk carriers and 70% lower for emissions from freight transport would be from road to
container ships. Ships also performed consistently better sea, or from diesel rail to sea. For example, a complete
than diesel rail, with the emission intensity being 72 – 84% transfer of freight from road transport to bulk carriers
lower for bulk carriers, and 43 – 64% lower for container would reduce emissions by more than 80%, and a transfer
ships. However, the uncertainty in emissions performance to container ships would reduce emissions by around 60%.
was higher for sea freight than for electric rail freight, Shifting freight to electric rail could also result in significant
suggesting that electric rail would provide more robust and emission reductions. For example, in 2050, the complete
reliable reductions in GHG emissions. transfer of freight to electric rail from the road, diesel
Air transport performed particularly poorly for the rail, and air transport would reduce WTW emissions for
movement of freight. For instance, when non-CO effects the route by 83%, 81%, and 99.6%, respectively. As noted
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were included, its emissions per tkm were, on average, in Part I, electrification of the Inland Freight line is not
41–50 times higher than those for road transport. When being implemented at this stage, but the results from this
compared with electric rail, the situation was even more WTW study suggest that it should be seriously considered

Volume 1 Issue 1 (2024) 17 doi: 10.36922/eer.3471