Procurement of alternatively-powered rolling stock (hydrogen or battery)

Shifting passenger and freight transport activities to rail is seen as a potential tool for achieving decarbonisation objectives given it is already an established low carbon intensity mode. Even so, there is still room to further mitigate railways' CO2 emissions by employing carbon neutral technology solutions. Electrification has been highlighted as a potential way forward, but electrification itself can carry high front end infrastructure costs. It is also highly dependent on the energy mix of the territory it is operating in. Various analysts have suggested adopting rolling stock capable of using alternative energy sources as an option for balancing environmental benefits with economic, commercial and competitive constraints. The fundamental physics of rail traction requirements, particularly freight pose a major challenge for alternatives such as hydrogen and batteries. Two main types of rolling stock have been highlighted: hydrogen technologies and battery ones. Hydrogen fuel cells can serve as a source of energy for propulsion with clean direct emissions: a chemical process converts the energy in the hydrogen molecule to generate electricity, as well as heat and water. How clean this technology really is will depend on the initial way in which hydrogen is produced. Steam reforming through fossil fuels can still entail high emissions, even if lower than conventional diesel combustion. Using electricity from renewable or nuclear energies can yield a cleaner form of propulsion than conventional fuels (depending on the energy mix) but is, at present, a more expensive option than the use of fossil fuels as the source of hydrogen. The development of a hydrogen based fuel system will entail the development and cost of a new and separate supply and logistics system. These must be included in any comparative economic evaluation. When it comes to battery-related technologies, these refer to the use of rechargeable batteries for powering rolling stock. Their main claimed advantages for decarbonisation purposes is linked to their lower comparative cost if compared to the infrastructure investment needed for electrifying the fleet. However, battery technology has not yet arrived at a situation where it has the energy density to support the operation of conventional freight even over relatively short distances. These are by their nature much heavier than passenger trains where battery applications have been trialled and demonstrated. The

option to use batteries for “last mile” applications to allow freight trains to operate directly in/out of terminals embedded within urban areas without the need of a separate diesel shunting or an integral I/C power pack may have potential.to service new markets which are wholly served by road at present. This model could yield significant decarbonisation and operational benefits. Hybrid vehicles, combining combustion fuels or hydrogen fuel cells with batteries, can also provide CO2 mitigation gains. In all cases, the weight and capacity of batteries can raise operational difficulties, such as not allowing for longer trips when battery capacity does not permit it. Battery technologies’ potential will also be dependent on the energy mix of the context of application. These two technologies are still being evaluated, as their mass uptake is only expected in the following 5 to 10 years, in a "best case" scenario. Empirical wider evidence will be needed to contrast current estimated benefits obtained from pilots and modelling exercises with real- life and sustainable applications of these technologies.

Impact on CO2 emissions

The CO2 mitigation impact in this case depends on the chosen technology, as well as on the energy grid of the context at hand. Hydrogen fuel cells are estimated to have mitigation potential: in the UK, simulations for a specific route showed that a hydrogen powered train and hydrogen-hybrid train led to 59% and 77% CO2 decrease compared to diesel propulsion. An overall analysis in Europe set the potential for CO2 mitigation at around 40%, compared to a diesel-propelled train scenario. Hydrogen potential depends on how it was generated: in the USA a recent analysis showed that hydrogen energy generated with renewable sources brings about 20 times more benefits than thermal electricity or natural gas generated hydrogen. Battery mitigation potential has been set lower: the same analysis in the USA estimates that the benefits brought about by batteries in terms of decarbonisation potential stand midway between hydrogen-based and diesel technologies.

In Montreal, a full electrification of a railway line brought about 98% of CO2 mitigation, compared to only a maximum of around 70% for -generated hydrogen - most of the electricity produced in Montreal comes from hydroelectric plants.

Electrification will generate net new energy demand for the utility companies. There will need to be adequate incremental capacity available to sustain train operations. The rail operators no longer provide their own power (as in the past) and will rely on the adequacy of national or international pooled grid supplies for effective operation. Given the rail system represents a wholly new market for the power suppliers potential collaboration between the generators, rail infrastructure managers and train operators might be useful developmental and commercial model to develop. Costs Procurement of hydrogen and battery rolling stock could in some circumstances be less expensive than traditional electrification, due to high initial infrastructure costs that electrification entails but with real limitations on train speed, weight performance and 24/7 availability. For instance, in a study for Montreal it was estimated that the electrification of a

commuter line would have cost around 1.3 billion CAD $, compared to only 655 million CAD $ for a hydrogen system. The electrification option had lower operational costs, but higher total costs due to the higher initial infrastructure costs. But these estimates did not take into account the costs of storage, distribution and production infrastructure for hydrogen. The claimed cost-related comparative advantage of the hydrogen fuel can be further eroded lost if there is enough concentrated condensed traffic demand for being able to increase the frequencies in one given electric line. Estimates indicate that In the US, overhead line equipment electrification has lower annual costs than all other cleaner technologies. This is expected to remain the case to 2050 and probably beyond. Estimations for years after 2020 put hydrogen fuel cells closer to diesel combustion in terms of costs. This was seen in recent analyses for the USA. Nonetheless, it will be necessary to add costs of the recharging stations for hydrogen, plus all related distribution and hydrogen production infrastructure. Batteries are less cost-competitive, as their cost is considerably higher and their performance is lower than hydrogen fuel cells. Nonetheless, this is expected to change as battery technologies evolve. In Norway, costs for full battery rolling-stock systems are estimated to gradually close in and almost equal those for hydrogen fuel cells ones by 2050. By that year, it is project that full battery rolling stock systems would cost around 16 MUSD/year, compared to around 15MUSD/year for hydrogen-based systems (though this is a highly specific case example with abundant hydro power availability). Co-benefits Hydrogen and hybrid-propelled trains can reduce energy consumption, thus potentially decreasing prices. Trials in the UK showed that the two technologies respectively reduced energy consumption in return journeys by 34% and 55% compared to diesel. At the same time, alternative technologies can have higher acceptance than other technologies: an analysis of potential adoption of alternative rolling stock technologies in the USA showed that battery-based rolling stock has a higher public acceptance (based on noise reduction, aesthetics and safety) than other forms of technology, including electrification. In the particular case of hybrid vehicles, they bring the added value of being able to take advantage of already electrified lines and shift to tracks which are not electrified without high infrastructure investments. At the same time, one of the highest co-benefits of this measure is its reduced costs vis-à-vis electrification for rail lines with low demand and train frequencies. Lowering the front-end cost of infrastructure electrification, speeding up the electrification process and seriously extending the life of the fixed equipment (masts, power supply etc) are options that could be readily pursued to secure decarbonisation and enhanced operational performance for railways. Other considerations One of the highest adverse effects of these alternative energy technologies is their much lower efficiency when compared with rail electrification: in the UK, a trial-based test for a fuel cell hydrogen train showed a generally low energy efficiency: at a duty-cycle peak of 14% and a steady-state peak of 17%. Trips for higher distances can also be harder, as battery and

hydrogen fuel cells’ life is not yet adapted for them. These difficulties could be improved with the provision of charging stations, hybrid vehicles and future technological improvements. Related research Chan, S.; Miranda-Moreno, L., Patterson, Z. (2013) Analysis of GHG Emissions for City Passenger Trains: Is Electricity an Obvious Option for Montreal Commuter Trains? http://dx.doi.org/10.4236/jtts.2013.32A003 Din, T., Hillmansen, S. (2017) Energy consumption and carbon dioxide emissions analysis for a concept design of a hydrogen hybrid railway vehicle. https://doi.org/10.1049/iet- est.2017.0049 Ehrhart, B., Klebanoff, L., Hecht, E., Headley, A., Ng, M., Markt, C. (2019) Impact of Hydrogen for Rail Applications. https://www.energy.gov/sites/prod/files/2019/04/f62/fcto-h2-at-rail- workshop-2019-ehrhart.pdf Hoffrichter, A. (2013) Hydrogen as an Energy Carrier for Railway Traction. https://etheses.bham.ac.uk/id/eprint/4345/9/Hoffrichter13PhD1.pdf Ruf, Y., Zorn, T., Akcayoz De Neve, P., Andrae, P., Erofeeva, S., Garrison, F., Schwilling, A. (Shift2Rail Joint Undertaking and Fuel Cells and Hydrogen Joint Undertaking) (2019) Study on the Use of Fuel Cells and Hydrogen in the Railway Environment. https://doi.org/10.2881/495604 Shift2Rail (2019) Study on the use of Fuel Cells and Hydrogen in the Railway Environment. https://shift2rail.org/publications/study-on-the-use-of-fuel-cells-and-hydrogen-in-the- railway-environment/ Zenith, F., Isaac, R., Hoffrichter, A. (2019) Techno-economic analysis of freight railway electrification by overhead line, hydrogen and batteries: Case studies in Norway and USA. https://doi.org/10.1177%2F0954409719867495