THE entire rail sector needs to design a common strategy to address the transition from diesel fuel if it is to remain the most sustainable form of land transport, a study on the sector’s pursuit of decarbonisation has concluded.

The study addresses the challenges and opportunities of phasing out diesel-powered rolling stock. It examined the European Union (EU) regulatory framework and some national strategies while providing a preliminary assessment of the alternative technology available and making clear recommendations to the European Commission (EC).

Launched in July 2022, it is the first phase of the Association of European Rail Rolling Stock Lessors’ (AERRL) study of alternatives to diesel fuel. It was conducted by the consultancy Eolos on behalf of AERRL as well as rolling stock leasing companies Akiem, Beacon and Cargounit, with support from European banks Crédit Agricole CIB, ING, KfW Ipex-Bank and Société Générale.

While the study says that electrification “remains the most efficient solution from a holistic perspective, complementary solutions can help accelerate decarbonisation.” Specifically, hydrogenated vegetable oil (HVO) is identified as an immediate candidate for existing diesel fleets, helping to reduce CO2 emissions by 85-90% and, according to the study, easy to implement. “Obstacles due to higher taxation can and should be adjusted by future regulation,” it says.

Renewable natural gas (RNG) and using ammonia as a fuel for internal combustion engines are considered short to medium-term options, although several operational challenges remain.

Hydrogen has a high energy density per kg, but the study states that “green production” is still very limited and requires high expenditure. Both hydrogen and ammonia are considered as later alternative solutions for heavy freight trains where electrification is not available.

For example, they could be used on “long non-electrified routes, and after substantial infrastructure improvements are achieved,” the study says.

In contrast, the study says that battery technology is a solution for the rail sector although “major problems remain.” Specifically, it says that dual-mode battery-electric trains combined with partial electrification could be a “game-changer” in the longer term.

The study adds that to enable the sustainable transition of the rail sector, different stakeholders need to come together in a “freight transport system for efficiency,” organised either by the EC or an appointed actor in the field. “The investments between rolling stock and infrastructure need to be balanced,” it says.

In addition, to achieve maximum leverage for industrial decarbonisation, the rail sector should be, after pipelines, the first choice for green hydrogen transport.

“With such a position in a new supply chain, the rail sector can increase its freight market share and provide safe and reliable low carbon-emission energy to today’s most emitting industries,” the study says.

AERRL chair, Mr Fabien Rochefort, describes the absence of an ambitious and aligned roadmap for near-term decarbonisation as the missing link in European rail policy.

“Working from this initial roadmap, we hope to hold further discussions, leading to a common project with all rail stakeholders and pushing policymakers to support our willingness to promote green transportation even further,” Rochefort says.

“The banks have supported this initiative by rolling stock leasing companies because we share their determination to continue to drive down emissions in the rail industry,” says Mr Robert van Duuren, director of transportation finance at ING, representing the banks that supported the study.

“We anticipate a combination of solutions will be needed to make progress in the real world, and I therefore find it interesting that the study describes multiple alternative technologies. We hope this initiative will motivate many actors to begin their transition.”

The full study is available here. AERRL will also host a webinar on May 4 at 12.00-13.15 UTC to present the key conclusions.