Hydrogen trains - a viable alternative to diesels in the UK?
By Paul Butterworth, Engineering Director, DB ESG (25. April 2018)
Over the last few months, there has been plenty of UK publicity and Government support for hydrogen trains.Can this new breed of vehicles really be a zero emission, diesel alternative for our network and be a robust alternative to rail electrification?
With the cancellation of railway electrification projects in South Wales, the East Midlands and the Lake District and with less than 50% of the UK’s rail network currently electrified, it looks like significant areas of the rail network will remain non-electrified, at least for the foreseeable future. When you couple this with the Government push for greener road transport, and a potential ban in the sale of new diesel and petrol only vehicles by 2040, it would follow that the Government cannot press ahead in making road transportation ‘greener’, whilst continuing to allow diesel vehicles to run on the railway. Therefore, in February 2018, Transport Minister Jo Johnson announced the intention to remove diesel only trains from Britain’s railways by 2040, a big ask when currently, 29% of the UK’s train fleet is diesel.
The Secretary of State for Transport currently believes that bi-modes (electric trains that have a self-propulsion capability), are sensible replacements for pure diesel units. In the immediate future this means that the viable bi-modes would be diesel-electric, and whilst these vehicles on paper deliver the best of both worlds, there are however several disadvantages, mainly since this type of vehicle carries two modes of propulsion; They can be more difficult to maintain, operational costs can be higher and because they have to carry both diesel and electric equipment, they are also heavier, increasing the possibility of track damage and therefore resulting in higher track access charges.
They also still produce harmful emissions and given the push to remove diesel vehicles, may only have a true operational shelf life of around 20 years. Longer term, the Government believe that hydrogen, rather than diesel bi-modes may prove to be the best alternative. This is supported by the announcement made by the RSSB Chief Executive Mark Phillips, also in February 2018, that the Rail Safety & Standards Board is working with Alstom, with the aim of piloting a hydrogen powered train in late 2019 or early 2020.
The Hydrogen Approach
So, what are the hydrogen options? Simply put, there a two main approaches that hydrogen powered vehicles can take to convert the chemical energy of hydrogen to mechanical energy. This can either be by burning hydrogen in an internal combustion engine or by reacting hydrogen with oxygen via electrolysis, in a fuel cell to run electric motors.
The other key question technology wise, is where does the hydrogen come from and how is it distributed? Typically, hydrogen can be taken from either the steam reforming of natural gas, or produced by the electrolysis of water. If electrolysis is used, the resulting hydrogen is branded as Green Hydrogen, which is emission free, whereas that produced using steam reforming still produces greenhouse gases albeit at lower levels than using diesel. Of course, there is the associated financial cost, with Green Hydrogen currently being significantly more expensive than steam reformed hydrogen or diesel, where the current costs could be deemed as comparable.
Whichever hydrogen source is selected, there’s still the question of how and where trains will be refuelled and the longer term, wider hydrogen infrastructure requirements. To counter this, hydrogen as a fuel would avoid the cost of infrastructure works on the live railway, and would reduce the amount of civil engineering, commissioning and maintenance required for electrification.
Of course the economic influences will be key. It is thought that the cost ratios of a hydrogen-based system could be equivalent to conventional overhead electrification, although the economic viability of hydrogen would depend on the allocation of the electricity price variability risk. There are also the influences of any potential risks relating to the development of new rolling stock or the modification of existing rolling stock, the associated hardware lead time and approvals, any unexpected reliability or performance issues and the need to potentially allay public concerns relating to the use of hydrogen.
Does a hydrogen rail product exist currently?
In reality, the concept of a hydrogen fuelled train has been around for a good number of years. The East Japan Railway Company developed a ‘Hydrail’ hybrid in 2006 which was powered by two 95kW fuel cells, and in 2010 the U.S. Army Corps of Engineers plus BNSF (a U.S freight network operator) and Vehicle Projects Inc unveiled a hydrogen-powered locomotive which used a 240kW fuel cell. The Republic of South Africa developed five 17kW mine locomotives in 2012. In 2013 the South West Jaitong University in China ran a 150kW locomotive, and in 2015 200kW hydrogen fuelled trams began operating in Qingdau, China. For us in the UK, our first real foray into hydrogen was a small locomotive developed by The University of Birmingham in 2012, although with a total output of only 4.4 kilowatts it was purely a vehicle to act as a technology display than have any commercial production intent.
The most current and directly applicable technology takes the form of the Alstom Coradia iLint train which was exhibited at Innotrans 2016. Alstom announced its first iLint order in November 2017, where the local transport authority of Lower Saxony in Germany ordered 14 Coradia iLint units, with an option for 33 more. These trains will replace the currently operating diesels in the region from December 2021. The vehicles will be deployed on the Weser-Elbe network and are currently undergoing trials in Germany and the Czech Republic.
The Push for Hydrogen in the UK
In the UK, a collaboration between Fuel Cell Systems Ltd, The University of Birmingham and Hitachi Rail Europe has completed a six-month study for the rail industry, which shows that hydrogen fuel cell technology can be successfully retrofitted to extend the life of existing rolling stock, to provide an interim position to new rolling stock. This study also established that fuel cells can provide a clean alternative for the next generation of self-powered regional trains in the UK, a clear endorsement for the political drive that we are seeing.
Rt. Hon. Chris Grayling MP has recently announced that Hydrogen powered trains are a ‘priority’. Speaking in the House of Commons on 18th January, Mr Grayling said: “I expect to see a transformation of technology on our railway over the coming years, with the introduction of different types of battery electric hybrid trains, and I see that as a priority. I want the first hydrogen train to operate on our rail network within a short period of time.”
It is therefore clear, that the current Government believe hydrogen trains are part of the future of our rail network.
Is this really a viable option?
Well, as always there are differing viewpoints, somewhat driven by the proposed applications and the current status of the technology. For example, Rail Freight Group Executive Director Maggie Simpson issued a note of caution, saying that whilst battery and hydrogen technologies ‘may show promise for lightweight passenger trains, their application for heavy duty freight is at best unproven, and setting an arbitrary deadline of 2040 could well therefore be counterproductive, damaging the case for investment’.
As such, the Rail Freight Group would like to see the remit of the Office for Low Emission Vehicles extended to cover all freight modes, where retrofit grants for buses and other road vehicles are extended to the railways, and the ‘continued affordable electrification of the strategic freight network’ is maintained.
For the passenger carrying stock, the current front runner in the Alstom iLint train is still at prototype stage, where it is being used in Germany to replace diesel vehicles on secondary lines only, but is not seen as an alternative to electrification there. Alstom have confirmed that they could develop a standard gauge version for the UK and that there could be a potential to retrofit the technology onto existing train fleets.
Alstom’s Managing Director for Trains and Modernisation, Mike Hulmes has said: “We’re working with Liverpool City region to establish a source of Hydrogen from the refineries in the Ellesmere Port area and we believe that the Liverpool area would be a good test case”.
With regard to the fuel itself, the efficiency of converting electricity to hydrogen and back again for rail traction is similar to that for a diesel engine, but it is still much less than for electric traction. The more environmentally friendly Green Hydrogen is also currently very expensive, and with the commercial operations in the UK, the distribution of this increased cost for lower emissions would need to be clearly defined. There is then the fact that the UK will also require the installation of a hydrogen supply infrastructure to link the gas to the depots and fuelling points. As commented in the previous paragraph, this may mean that a key influencer in the deployment of hydrogen rail vehicles is more localised based on availability and ease of fuel supply.
What will happen? The move to a truly low emission, low carbon rail infrastructure will require a blend of different technologies and the development of a range of guiding policies. Hydrogen as a fuel and as a technology application, I am sure will play a part in this, but cannot provide the whole answer. It will be the concerted, aligned drive of the industry as a whole, coupled with those defining policy and the application of the most cost efficient technologies that will push us forward to the low carbon railway we need and desire.
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