• The project analyses the real feasibility of using LNG in heavy rail traction
  • It seeks to identify the technical, normative and regulatory adaptations needed to develop its commercialization in the short/medium term

On 24 and 25 October 2019, the Consortium formed by Renfe, Enagas, Naturgy and Bureau Veritas participated in the 10th Congress on Railway Innovation held in Mérida (Spain) to disseminate the RaiLNG project through an information stand and a conference. Throughout his presentation, Claudio Rodríguez Suárez (Enagas, General Director of Infrastructure) focused on the following topics:

  • Railway as a lever to reduce the trend of emissions from land transport: Risks and opportunities.
  • Alternative solutions for “unprofitable” electrification railway lines and services under a life-cycle perspective of the energy chain for railways: “Roadmap per traction segment”.
  • Natural gas as a multi-segment solution and a vector for the development of more sustainable solutions in the HH segment through “blending with H2”: RaiLNG project.

What problem does the RaiLNG project address?

According to the report ‘A sustainable energy model for Spain in 2050’ by Deloitte, 37% of the railway networks are still not electrified, so 40% of the final energy consumed in the railway sector is not electric. Data from the Ministry of Development indicate that in 2013, 74.1% of rail transport used electrical energy and in 2000, this percentage was 65.3%.

The reason why these lines are not electrified is economic, although it has a significant environmental impact. The consequence is that diesel locomotives continue to be purchased to cover the non-electrified lines.

With these data, the decarbonization of road transport, responsible for 75% of emissions from the transport sector, is limited both by the lack of 100% renewable solutions applicable to all segments and the strong upward trend in demand and by the inefficient use of multimodality.

What is the most competitive solution?

Moving traffic to the railways, up to 12% more efficiently, is the most competitive solution. With a transfer rate of more than 1%, this is achieved:

  • Reduce energy consumption by +2%.
  • Reduce CO2 emissions from the transport sector by +1.6%.

However, this medium accumulates a progressive loss of “modal share” due to:

  • A more demanding regulation;
  • Its lesser flexibility in the face of less and less “like-minded” demand;
  • Interoperability conditioned by the different existing electrification systems;
  • A residual non-electric park based on uncompetitive diesel technologies (50% of which do not comply with environmental regulations) and whose electrification is not profitable in most cases.

In this scenario, the factor with the greatest short-term impact is the improvement of the competitiveness (efficiency/exhaust) of the “residual” fleet through alternatives to its “motor-fuel” binomials.

So how did the RaiLNG project come about?

After several European projects aimed at seeking solutions based on improving existing technologies, in 2015, Renfe, Enagas and Naturgy developed a “roadmap” to establish an alternative that would be technically viable in the short term and that would be both environmentally and economically sustainable for any traction segment.

The consortium determined that natural gas was the most suitable alternative fuel, due to factors such as:

  • Security of supply;
  • Price;
  • Associated investment;
  • The efficiency of use;
  • Emissions;
  • Technological maturity;
  • Safety of use and
  • most especially, hybridization.

However, in the medium and long term, it was necessary to promote disruptive and alternative technologies that would allow their progressive hybridization with new 100% renewable solutions such as biomethane and hydrogen.

What are the main advantages and disadvantages encountered?

At present, the development of such a “road map” has identified the following pros and cons:

  • Pros:

Remarkable improvement of the “Life Cycle Cost”:

  • -40% compared to diesel platforms;
  • -240% concerning total electrification, and
  • -350% compared to the use of a fuel cell (solution currently limited by power to the automotive travel sector).
  • Cons:
  • Increasing environmental response to natural gas based on uncertainty about the impact of methane emissions.
  • Potential limitations at medium and high powers due to the need to use “dual” solutions on diesel technology, which conditions both the capacity of LNG to break down (CH4-NOx imbalance) and its competitiveness against an “improved” and more evolved diesel, which is the reason, together with the drop in oil prices, for the decline in the promotion of these technologies in North America.

So, what does the RaiLNG project prioritize?

It is precisely given to the advance towards the commercialization of 100% LNG solutions in the DMU segment (GMU) in the 2020 horizon, that the RaiLNG project has prioritized its action with a specific proposal for the Heavy Haul segment with the objective of:

  • Based on the “lessons learned” from the projects developed in the USA, complete an intensive phase of track testing, aimed at having sufficient information to identify the real viability of the use of LNG in heavy rail traction and, where appropriate, the technical, normative and regulatory adaptations required to develop its commercialization in the short/medium term.
  • Analyze the viability of using heavy conventional engines (MACI) for partial combustion (blending of up to 20-30% of H2 and LNG) and/or total (100%) hydrogen as a transition solution that allows the extension of the use of H2 in the railway in all segments and the consequent use of multisegmented energy synergies, pending the viability of 100% renewable and high-performance solutions (fuel cells).

This work is therefore presented as a review, from the practical experience developed by Renfe, Enagas and Naturgy in Spain, of the “state of the art” and future perspectives of the alternatives to the engine/fuel binomial applicable to the railway segments of unprofitable electrification and with both a social (secondary passenger railways) and significant environmental effect (freight).