Green hydrogen, as we are regularly told, is a fuel of the future (or energy vector, if we are to be pedantic). For those hard-to-reach parts of our transport and industrial sectors, where batteries just won’t cut the mustard, hydrogen is seen as the alternative route to a net-zero carbon future as the replacement for the humble diesel engine.
Many know the story around this for UK rail. Studies such as Network Rail’s Traction Decarbonisation Network Strategy (TDNS) and RSSB’s work on decarbonization through the DECARB research program are telling us that we should put the wires up where we can, use batteries for less intensive applications where we can’t, and hydrogen will fill the gaps where we need higher levels of on-board energy storage.
So far, so good. However, we’re yet to see a battery electric or hydrogen train in passenger service in the UK. Batteries are nearly there, although concerns around battery life linger, requiring oversized and consequently heavy and expensive battery systems to withstand the punishing duty that rail imparts. Hydrogen has seen running prototypes, built mostly from humble origins on old rolling stock, but we are yet to see real passenger operation, or have a plan for this in any meaningful way.
The barriers become more significant when we start digging a little deeper. As with the introduction of any new system, there are wide-ranging consequences, which must all be managed together driving up costs and risks for transition. Whilst we are ripping out our trusty diesel engines in the vehicles and replacing them wholesale with hydrogen fuel cells and storage systems, we’re doing so on electric units that may not be matched to the non-electrified network that they will operate on.
We also must consider the infrastructure requirements; hydrogen refueling at depots, hydrogen supply and logistics (do we have this tanked in or generate on site?), safety, training, and socialization of the new hydrogen systems to train crews, maintenance and engineering staff. The costs of transitioning this all at the same time – vehicles, depots, operations, staffing and so on are enormous and far more than just the cost of some refurbished or new trains, a subject explored in the RSSB DECARB project T1199.
What if there is another way to manage this process?
If we accept that hydrogen is a must (and at this time, it is, as part of the range of solutions that will move us away from carbon-intensive transport), how can we minimize the pain of the transition? Recognizing that there are risks on all sides of the hydrogen equation from both technical and commercial perspectives, what if we can stagger these, allowing us to focus our energies (and cash) one step at a time?
There is a way to do just that. It isn’t quite so exciting as the wholesale hydrogen fuel cell future but might just give us enough breathing room to achieve that goal in the long term.
Using hydrogen within a fuel cell, generating electricity directly in an electro-chemical process in relative silence and with just water emitted from the tailpipe is the preferred route forward, but there are significant challenges to this transition. For older rolling stock at mid-life in particular, the costs associated with converting either electric or diesel units to hydrogen fuel cell operation just don’t stack up.
However, there is renewed interest across the globe in using hydrogen to burn cleanly within the internal combustion engine (ICE). New developments allow us to burn this using existing diesel engine hardware with minimal intervention. Traditionally hydrogen ICEs used petrol engine architecture for combustion, which is not generally robust enough for heavy duty commercial applications such as rail. Those engine manufacturers investing heavily in fuel cell technology have, in the past few years, turned their attention back to hydrogen ICEs. The majority of the commercial engine manufacturers have now announced hydrogen engines (MAN, JCB, etc.), or are known to be developing them (I can’t mention names, but they are well known to our industry).
What does this mean for rail? If you can burn hydrogen, cleanly, in our existing diesel-powered rolling stock with minimal intervention, this may well make running our mid-life fleet on hydrogen a viable option. Costs to implement will be significantly lower than replacing the entire traction system. It could accelerate the implementation of hydrogen into our rail network, at a lower risk, on known rolling stock, allowing focus and funding to be directed to the infrastructure, logistics and socialization of hydrogen within our industry.
This stepping-stone approach can provide a more controlled pathway to our hydrogen future, with risks distributed across a larger timeframe. In parallel it will give the emerging technology of the fuel cell systems time to adapt to the demands of rail without the immediate pressures to perform, creating space for robust development so that when new rolling stock does come onto the rails, it will have been given the time to use a solution that is fit for purpose and not one that is still relatively unknown.
The rail industry is facing an unprecedented time of change. Carbon and the environment, digitalization, globalization, how we live and work, not to mention pandemics are all changing our requirements for rail and transportation. We need to give ourselves all the help we can in an industry that isn’t equipped for such rapid change. Perhaps this option gives us the best chance to secure a sustainable transport future without big bang risks in this brave new world.
For more information on hydrogen internal combustion engines, join me at the Electric and Hybrid Rail Technology online conference on March 17, 2022.
About the author: Jonathan Brown, Global Decarbonisation & Sustainability Lead, Ricardo Rail
Delivering technical engineering projects for Ricardo’s global customer base since 1998, Jonathan’s experience covers the design and development of internal combustion engines and clean energy propulsion systems in rail. Initially working in analysis and simulation prior to a role as chief engineer in the Large and Industrial Propulsion team, he has been responsible for leading clean-sheet design and development programs for OEMs in the automotive, rail, marine, power generation and industrial sectors.