Freight

World freight demand is growing rapidly, driven by economic globalization and information technology ¹. World freight volumes were as follows in 2015.

World freight volumes by mode in 2015. Sources: International Transport Forum ², as reported by Martime Executive ³.

Energy and Emissions in Freight

Different freight modes require substantially different amounts of energy to move a ton of cargo one kilometer.

Sources: Bureau of Transportation Statistics (⁴ and ⁵), Bushnell and Hughes ⁶, Davis and Boundy ⁷, Gellings ⁸, Melton and Hochstetler ⁹, van Essen et al. ¹⁰.

Likewise, different modes emit substantially varying levels of greenhouse gases.

Sources: Melton and Hochstetler ⁹, Responsible Care et al. ¹¹, EIA ¹².

Trucks with larger loads tend to have lower energy requirements per ton-km, and long haul flights tend to have lower energy requirements than short flights ¹³.

Airships are not used today for freight, but designs under development may play an intermediate role between trucking and aviation. Hybrid airships, assessed above ⁹, are not fully buoyant and rely on a combination of buoyant, aerodynamic, and propulsive lift. Other novel designs, such as a concept that uses the jetstream for propulsion, may have significantly lower energy needs ¹⁴.

Energy Savings Potential

There is potential to reduce energy consumption in freight through efficiency of ships, trucks, and aircraft, and also through shifting some truck freight to rail.

Data from Eide et al. ¹⁵ for shipping, IEA ¹⁶ for trucking, Schäfer ¹⁷ for aircraft, and Kaack et al. ¹⁸ for shift from trucking to rail.

Historically, overland freight has shifted from rail to trucks; it is unclear whether this trend can be reversed and to what degree ¹⁸. Greater energy savings may be possible through novel aircraft design ¹⁸ and truck platooning ¹⁹.

Shipping

Almost any mainstream fuel can, in principle, be used to power cargo ships, but not all options are practical.

See sources for further analysis of heavy fuel oil ²⁰, liquified natural gas (LNG) ²⁰, synthetic and biomethane ²¹, alcohol-based fuels ²¹, ammonia ²¹, hydrogen ²⁰, sails ²⁰, batteries ²², and nuclear shipping ²³.

Methane, alcohol, and ammonia are low-carbon fuels only insofar as they are produced through low-carbon processes. They are nonetheless considered the most promising near-term low-carbon fuel options because they can be used in existing ships without major technological advances or infrastructural overhauls ²¹, ²⁴.

At present, it is difficult for low-carbon options to compete with fuel oil or LNG.

Methanol figures are provided by Ming et al. ²⁵ and the rest from Nelissen et al. ²⁶. All figures are CPI-adjusted to 2020. A carbon price of $50-100 is assessed for all fossil-based fuels. Price estimates for methanol were prevailing prices in 2010, and for other fuels are estimated prices in 2030.

Most ship engines today are designed for heavy fuel oil, including in ships under construction, but alternative fuels are gaining ground.

By comparison, 99.7% of ships as of 2018 are designed for heavy fuel oil. Source: DNG VL ²⁷.

See our ammonia and methane analyses for more details on these as shipping fuels.

Trucking

Long-distance trucking is one of the most challenging sectors of the economy to decarbonize.

See ²⁸ for analysis of electric and hydrogen options and ²⁹ for DME.

Advances in battery technology may soon allow electric freight trucks with ranges of 300 km or more ³⁰. Dimethyl ether, which can be refined from methanol, is appealing in that it requires only minor truck modification. See our methanol analysis for more details on dimethyl ether as a trucking fuel.

Catenary wires are often used today for rail and municipal buses. We estimate the costs and benefits of WSDOT (the Washington State Department of Transportation) extending them to long-distance trucking as follows.

An assessment of the costs and benefits of installing catenary wires on the I-5 corridor between Seattle and the Columbia River. A 5% discount rate, 50 year infrastructure life, and $50/ton carbon price are used. WSDOT is used for total travel information. Ainalis et al. give per-km infrastructure, maintenance, and truck costs, and the pilot estimate is used. Mareev and Sauer give energy consumption estimates for the wire scenario and diesel baseline. Carbon intensity figures are from the EIA. Diesel prices are from the AAA. Electricity prices from Electric Choice. Diesel emissions are from the EPA. Our Transportation Fuels analysis converts to a per-kWh cost for diesel. An exchange rate of 1.39 USD per pound is used.

Sources: Ainalis et al. for data on costs of infrastructure, maintenance, and truck upgrades ³¹, AAA for diesel prices ³², Electric Choice for electricity prices ³³, Mareev and Sauer for energy consumption for wires and diesel trucks ³⁴, U. S. EIA for statewide emissions factors ³⁵, U. S. EPA for diesel emissions ³⁶, and WSDOT for trucking distance statistics ³⁷.

This project does not look like a good investment. Results are highly sensitive to the discount rate, estimated lifetime of infrastructure, and carbon price. The project may be more attractive if air pollution is taken into account, or if the cost of catenary wires is smaller after other jurisdictions have installed them. A similar analysis in the UK ³¹ found a much more favorable case for catenary wires there, in part because of the higher cost of diesel.

Last Mile Delivery

In logistics, the last mile refers to the transportation of goods between local distribution centers, retailers, and consumers.

The use of e-bikes ³⁸, and potentially drones ³⁹, ⁴⁰, to deliver small packages may save energy and road space relative to truck delivery ³⁹, ⁴⁰. With anticipated technological improvements, it is estimated that drone delivery may be viable for up to 30% of European citizens ⁴¹. We estimate the following energy costs of the delivery vehicle, per package.

Sources: E-bike energy from González et al. ³⁸ and other figures from Stolaroff et al. ⁴⁰.

Since e-bikes and drones are shorter range vehicles, more warehouses are needed if these are the primary delivery mechanisms. The following are per-package estimates of greenhouse gas emissions of package delivery, taking into account vehicle manufacture and warehouse operation.

Most figures are reported by Stolaroff et al. ⁴⁰. For e-bikes, we assume that the bike itself requires one sixth the energy as a large drone delivery, as estimated by González et al., and we assume the warehouse distribution is the same as in the large drone scenario of Stolaroff et al.

If drone delivery become widespread, it is likely to lower the cost of package delivery and increase overall e-commerce volume ⁴².

References

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3. Martime Executive. "Global Freight Demand to Triple by 2050". May 2019. ↩

4. Bureau of Transportation Statistics. "Table 4-25M: Energy Intensity of Class I Railroad Freight Service". Accessed May 28, 2020. ↩

5. Bureau of Transportation Statistics. "Truck Profile". Accessed May 28, 2020. ↩

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26. Nelissen, D., Faber, J., van der Veen, R., van Grinsven, A., Shanthi, H., van den Toorn, E. "Availability and costs of liquefied bio- and synthetic methane: The maritime shipping perspective". CE Delft, prepared for SEA\LNG LTD. March 2020. ↩

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31. Ainalis, D. T., Thorne, C., Cebon, D. "White Paper: Decarbonising the UK’s Long-Haul Road Freight at Minimum Economic Cost". The Center for Sustainable Road Freight. July 2020. ↩ ↩²

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40. Stolaroff, J., Samaras, C., O'Neill, C., Lubers, A., Mitchell, A., Ceperley, D. "Energy use and life cycle greenhouse gas emissions of drones for commercial package delivery". Nature Communications 9, Article Number 409. February 2018. ↩ ↩² ↩³ ↩⁴

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