Making road freight less carbon-heavy involves hard technical problems. So is it better to shift to rail or water? Parth Vaishnav and Lynn Kaack reviewed approaches to freight around the world in a systematic review in Environmental Research Letters (ERL)
Why did you decide to review decarbonization of road freight?
Road freight emits a large share of total greenhouse gas emissions but few serious attempts have been made to lower its contribution. While there is considerable potential for efficiency gains in trucks, deeper decarbonization of road freight is difficult. In particular, the need for trucks to carry heavy loads for long distances between refills or recharges makes it very hard to electrify road freight.
We wanted to take stock of what the literature said about the problem, and the various solutions on offer: from inventing carbon-free liquid fuels to using hydrogen or clean electricity. We concluded that most of these approaches involved hard technical problems that were unlikely to be solved in the near future.
Shifting freight to lower-emissions and electrified modes, most importantly rail, is crucial to making deep cuts in greenhouse gas emissions, particularly in the medium term. Limiting this effort to industrialized countries is not sufficient, as much of the growth in freight is happening in developing countries. This is why our topical review provides an overview of modal shift in all regions of the world.
What did you discover?
We compiled and published a dataset of freight activity (in tonne-km) for road, rail and water for 157 countries for 2000–2017, which allows us and other researchers to observe changes in modal split.
Clean energy is vital – but still not enough
We found that road freight activity already dominates in many parts of the world and its share is still on the rise. Two-thirds of land freight is transported on road, rather than by rail or on inland water, we discovered, based on countries where data are available. It surprised us that, despite its relative importance, only 75 countries reported data on road freight. This may be because the fragmented nature of the road freight sector and the reluctance of truck operators to collect and share data make it expensive for governments to collect this data through surveys.
With our topical review, we also provided a detailed overview of strategies for promoting modal shift in freight transportation. We analysed which policy approaches are taken in different regions of the world and identified barriers to shifting freight to rail for all or part of its journey. In many places, rail is seen as less reliable and flexible than trucks. It is also the case that supply chains are run to optimize what matters for firms: their profits. Policies generally do not “charge” firms for the long-term damage that greenhouse gases and other emissions cause to the environment and to human health.
the need for trucks to carry heavy loads for long distances between refills or recharges makes it very hard to electrify road freight
Parth Vaishnav and Lynn Kaack
We found that rail and rail intermodal – when a good is transferred between different modes of transport in a single container — could be strengthened by infrastructure investments that help rail to run more efficiently and reliably, and to shift cargo (e.g. containerized goods) quickly and without damage between rail and other modes. This includes terminal investments and new information and communication technologies (ICT). Governments should also level the playing field by charging trucks for the pollution they cause and for the damage they do to infrastructure such as roads and bridges; or by banning the most polluting types of vehicles outright. This would create a financial incentive to shift to modes such as rail.
We also discovered that not many countries have sufficiently robust, or even any, policies in place.
We have made public the raw data on freight activity that we collected from various government and academic sources; we are not aware of any other source that makes these data available in one place.
The topical review draws partially on a workshop we organized in February 2017 that involved 30 participants from industry, academia, NGOs and government.
What action should we take as a result of your findings?
There is a great deal of attention paid to decarbonizing light and passenger transport, for example, through electric cars. However, growth in demand for liquid fossil fuels is likely going to be driven by growth in heavy freight (see this article based on the IEA World Energy Outlook). Staying off this trajectory will require robust policies.
In regions such as the EU, policy-makers have worked for some time to reduce the amount of freight transported on roads. However, many other countries, including the US, are not using many of the policy instruments that could promote modal shift. We need to start a more serious worldwide attempt to decarbonize freight, and we hope our topical review can provide a stepping-stone for both researchers and policy-makers to work on this topic.
How will you take your research forward?
We were astonished by how few data are collected on road freight transportation, especially in developing countries. We are currently exploring whether passively-collected data and new analysis and computing methods could open new opportunities for governments to monitor the freight sector. We are working on a project that is intended as a proof of concept.
We also want to address other research questions, for example, what technical or engineering advances are needed? What infrastructure needs to be built and where? What policies ought to be put in place and what unintended consequences might they have? If less coal is transported by rail, as is occurring in the US, might that have an effect on — or create an opportunity for — modal shift?
