Fast as a plane, clean as a train

Global demand for fast, long-distance travel has reached again pre-COVID levels, and it is expected to continue to grow in the coming decades. The current demand is largely met with air travel, which presents significant environmental challenges like high greenhouse gas emissions. Rail systems, while environmentally preferable, are usually slower, currently face limitations in capacity, and thus require substantial infrastructure expansion to meet growing demands. The proposed mode of transportation called hyperloop presents a potential solution to an urgent need for fast, low-carbon, long-distance travel. 

Researchers at the Laboratory for Energy Systems Analysis at the Paul Scherrer Institute PSI have evaluated the potential environmental impacts in the first comprehensive environmental life cycle assessment (LCA) of a hyperloop system. For this, they teamed up with partners at ecoinvent, a Zurich-based organization that compiles material and energy inventories to support environmental assessments and provides the world’s leading LCA database, and EuroTube, a non-profit research organization in Dübendorf near Zurich working to develop a hyperloop system. Together, they came to the conclusion that the hyperloop concept is indeed promising: Hyperloop transit could be as fast as a plane and as clean as a train, but only if two specific conditions are met.

Only 5% of the climate impact of a flight

Hyperloop is a high-speed transportation system featuring end stations and pods traveling on tracks within low-pressure tubes made of either concrete or steel. The pods use magnetic levitation to glide along the tracks in a near-vacuum environment, minimizing friction and aerodynamic drag. This proposed system can carry passengers and cargo. Research and technology development for hyperloop systems is ongoing, and there is currently no hyperloop system in service. Likewise, comprehensive assessments of their environmental impact were lacking.

The new study now fills this gap. It is a first-of-its-kind environmental LCA of a hyperloop system and was recently published in the journal Resources, Environment and Sustainability. In their study, the scientists compare proposed hyperloop systems to high-speed trains and aircraft within a European context. Their finding: hyperloop does have a strong potential as an energy-efficient, low-carbon, high-speed transportation option.

For example, in terms of climate change impacts, hyperloop systems emit only 5% of the greenhouse gases a conventional aircraft would on the same journey. Similarly, compared with e-kerosene flights, the hyperloop wins by a large margin, having only a fourth of the climate impact a very short-haul flight powered with such carbon-neutral fuel would have.

The researchers’ analysis demonstrates that the climate impacts of a hyperloop transport service over its entire life cycle would be similar to those of trains. This conclusion hinges on two specific conditions:

1. The occupation rates of hyperloop have to be similar to those of current long-distance trains, though preferably higher.

2. The electricity supply for hyperloop operation has to be associated with low greenhouse gas emissions. To be precise, the hyperloop system must use an electricity mix with similarly low emissions as that which the Swiss Federal Railways are expected to use in the same future scenario.

A first-of-its-kind environmental life cycle assessment

To conduct the LCA, the researchers employed established methods and tools in a novel way. Romain Sacchi, who is a researcher at the PSI Laboratory for Energy Systems Analysis LEA and one of the authors of the study, explains that, since hyperloop technology would only be implementable in decades, using classical LCA databases that reflect the current state of electricity production and other key figures would be inconsistent and lead to incorrect results. Hence, Sacchi says, “we modified key sectors of the LCA database with different future Swiss scenarios to avoid misestimating its environmental impacts.”

“The starting point of our calculations was a software package called premise, which was originally developed within LEA,” says Christian Bauer, another researcher at PSI-LEA and likewise an author of the study. Premise is an open-source Python library that modifies LCA databases. The researchers used it to integrate the Swiss Energy Perspective 2050+ net-zero scenario into ecoinvent’s LCA database. With these tools combined, they could conduct the prospective assessment of the hyperloop life cycle.

Hyperloop offers prominent results amongst evolving transportation solutions

“We do acknowledge several challenges,” says Sacchi. Developers frequently mention potential regulatory hurdles, as introducing new infrastructure requires a certain amount of political will. Then, there is the technical feasibility and possible safety risks. Finally, although the hyperloop operates in a near vacuum, it still requires substantial energy.

Nonetheless, this research indicates that the hyperloop can indeed combine the speed of an aircraft with the relatively low environmental impact of a train, addressing a significant gap in the future transportation network and contributing to meeting climate targets.

The researchers highlight that among the emerging transportation technologies – such as electric or hydrogen fuel cell-powered airplanes, SAF, and advanced rail systems like the Maglev Trains in Japan, Korea, and China – the hyperloop stands out as the most promising in combining speed and capacity. However, they caution that the hyperloop is the least developed of these options and, if pursued, is likely to be the last to become operational.