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

CO -e/pkm in 2018, which is only slightly lower than the of the future fleets for all transport modes.
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value from this study. However, this included a weighting • More detailed consideration of alternative fuel
factor of 1.7 for non-CO RF effects. Another recent review pathways.
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noted that studies have estimated WTW emission factors • Extending the analysis to include:
from 74 to 313 g CO -e/pkm (average 145 g/pkm), but the (a) Other operational modes for shipping
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inclusion (or otherwise) of non-CO effects is not noted. (i.e., maneuvering and at anchor);
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For air freight transport, the mean 2019 WTW (b) A detailed analysis of AIS data for shipping on the
emission intensity from this study is 1,345 g CO -e/tkm, Brisbane-Melbourne route to characterize transit
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excluding non-CO RF impacts. The IEA does not publish conditions;
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corresponding global statistics for freight transport, and (c) Full lifecycle emissions (fuel cycle and vehicle
for WTW emissions, there does not appear to be any cycle).
other comprehensive review. The study for the EEA In addition, it would be beneficial to consider a wider
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determined an average WTW emission intensity of 1,036 g range of transport situations, scenarios, and geographical
CO -e/tkm, which is slightly lower than the value from this scales, as well as developments in technology and policy.
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study. However, EEA included a weighting factor of 1.7 for A more thorough treatment of transport planning and
non-CO RF. operation would also be desirable. Such additional work
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Concerning sea freight transport, the mean 2019 would help to highlight the practical significance of the
WTW emission intensities from this study for bulk work to policy-makers, industry stakeholders, and the
carriers and container ships were 7.5 g CO -e/tkm and broader community.
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15.5 g CO -e/tkm, respectively. The corresponding values 5. Summary and conclusions
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in the EEA study for bulk and container ships were 4.4 g
CO -e/tkm and 7.7 g CO -e/tkm. For the ship sizes used In Australia, reducing GHG emissions from transport will
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in the analysis, a study in the Netherlands obtained values be crucial to achieving national and state emission targets.
of 5.0 – 6.6 g CO -e/tkm for bulk carriers and 18.5 – 23.7 g This analysis considered the potential GHG emission
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CO -e/tkm for container ships. This comparison suggests benefits of transferring passengers and freight from high-
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that the results from this study aligned reasonably well intensity modes to low-intensity modes between two major
with recent studies in the international literature. cities in Australia, Brisbane, and Melbourne. The analysis
addressed a significant knowledge gap by providing up-to-
3.6. Transport mode shift tool date WTW emissions based mostly on current emission
The outcomes from this study have been used to create a models and local data. Such information has previously
transport mode shift tool, which is available free of charge been unavailable or limited in Australia.
for non-commercial purposes. The tool estimates the The analysis showed that a transfer of passengers from
average GHG emissions performance, expressed as either g air or road to electric rail, and a transfer of freight from
CO -e/pkm (passenger transport) or g CO -e/tkm (freight road to sea or electric rail, have the potential to significantly
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transport) for different transport mode mixes. The tool can reduce WTW emissions from the transport sector in
be run in deterministic or stochastic mode and estimates Australia. It provides valuable quantitative information to
mean and median performance values, as well as plausible help researchers, policy-makers, transport planners, land-
ranges. use planners, and network operators to quantify, design,
4. Other aspects and future work and implement mode-shift measures to reduce emissions.
It is acknowledged that the analysis did not consider the
Although this was beyond the scope of this paper, the mechanisms by which mode shift could be achieved, and
probabilistic approach can be used to quantify the the implications for emissions of the construction of new
importance of the model input variables on the simulation rail infrastructure, which are possible directions for future
outputs. This can be done through a sensitivity analysis and research.
is recommended for future work. The work presented here The analysis also demonstrated the capabilities of
could be refined and extended in several ways, including, recently developed Australian tools, and the merits of using
for example: a probabilistic approach, for estimating WTW emissions,

• Further evaluating model performance against real- noting that probabilistic methods have not typically been
world energy use and emissions, as well as against used for this type of study. For future work, it would be of
other models, data, and approaches. interest to compare the outcomes with similar studies that
• Further analysis of uncertainty in improvement rates use other models, data, and approaches.

Volume 1 Issue 1 (2024) 16 doi: 10.36922/eer.3471