BADEN-Württemberg is the latest German state to join a revolution underway in railway traction, which promises to bridge the gap between diesel ubiquity and electric sustainability.

State-owned leasing company Baden-Württemberg State Rail Vehicle Authority (SFBW) confirmed on March 17 that it is purchasing 20 Mireo Plus B battery-electric multiple units (BEMU) from Siemens for operation on Network 8 of the Ortenau regional system. The state follows Rhine-Main, Schleswig-Holstein, Mid Saxony and Lower Saxony in procuring alternative traction passenger vehicles to replace diesel trains in recent years.

Siemens’ BEMU solution complements a fuel cell-powered train, which it is developing with the support of fuel cell supplier Ballard Power Systems, Canada, and its EMU platform. Indeed, the manufacturer says it is no longer in the business of supplying diesel multiple units as the market declines due to growing environmental concerns over transport emissions.

Competitor Alstom remains active in this field, winning contracts in Germany in 2019 to supply eight Coradia Lint DMUs to East German Railway Company (Odeg), 18 vehicles to SFBW and 41 to Transdev to operate services in Bavaria. The manufacturer also proudly proclaims that it now possesses a complete traction portfolio after winning a contract to supply 11 BEMUs to Mid Saxony in February.

Alstom pioneered hydrogen fuel cell trains with its Coradia iLint multiple unit. Two prototype trains have been in service on the Elbe-Weser network in Lower Saxony since September 2018 while the supplier secured its first major contract in November 2017 when Lower Saxony Transport Authority (LNVG) placed an order for 14 trains, which will enter service from 2021. This was followed in May 2019 by a deal with Rhine-Main Transport Authority (RMV) subsidiary Fahma for 27 vehicles, which will enter service from 2022. The supplier is also actively testing the concept to drum up further interest in the technology. This included a tour of German states during 2019, and the Netherlands, where trials concluded last month. Tests are set to begin in Austria later this year after Alstom won a tender to operate a hydrogen pilot last month.

“Operators are looking at options to no longer tender for diesels trains,”

Ms Katrin Seeger, project manager for business development of alternative drive systems for regional trains at Siemens

Stadler, Hitachi and CAF are similarly active in the alternative traction market as demand for these types of solutions gathers pace. As well as Germany, France is set to begin introducing hybrid trains later this year and begin a trial with hydrogen in 2022 as it targets the elimination of diesel traction by 2035. Britain is also testing hydrogen and battery solutions, while Norway is exploring replacing diesels with battery trains, and Austria, as well as the Coradia iLint trials, is currently testing a Siemens Desiro ML BEMU in passenger service.

The European Union’s targets for decarbonisation of transport as part of its Green Deal is reinforcing this desire to explore alternative traction. The EU Transport White Paper of 2011 targets a 30% reduction in CO₂ emissions by 2030, 50% by 2035 and 90% by 2050. Electrification and the use of sustainably sourced electricity is the preferred solution. However, the continent is a long way from ubiquitous electrification: approximately 54% of railway infrastructure in the EU 27 countries plus Britain was electrified at the end of 2017.

Many countries do have significant electrification programmes, notably Germany, which is targeting 70% electrification by 2030, up from 52% today. However, putting up wires is expensive and depending on the source of the electricity is not always green. In addition, the economics of delivering complete coverage often do not add up, particularly for low density lines. Execution has also proven problematic in recent years, especially in Britain where diesel remains the primary form of traction on many main lines. Plans for further electrification projects are now seemingly on the backburner despite the government targeting a zero-diesel railway by 2040.

Other European networks with significant non-electrified sections and potential for alternative traction include the Scandinavian countries, Belgium, the Netherlands, Spain, Ireland, and Italy.

In North America diesel is king. Despite some alternative traction trials, notably with LNG and CNG, Class 1 freight railways continue to operate diesel trains over vast distances. The North East Corridor is electrified as are some commuter lines although the majority serving cities in the US and Canada use diesel traction. Likewise, Australia is a diesel country as is Brazil, while great swathes of Russia’s network relies on diesel traction as do networks in Asia, Latin America and Africa.


Mr Jürgen Blassmann, director of rail business at MTU Friedrichshafen, says the cost - approximately €1m per km - meant the prospect of complete electrification threatening the company’s diesel traction business was never realistic. However, the supplier is embracing alternative traction drive systems through solutions including MTU Hybrid PowerPacks as a means of diversifying its offer due to changing demand from customers.

MTU Hybrid PowerPacks production

Indeed, Ms Katrin Seeger, project manager for business development of alternative drive systems for regional trains at Siemens, says the supplier has witnessed a growing appetite for its alternative traction solutions from all over the world, including operators in North America and Australia. In Europe, she says tenders increasingly request a particular type of traction even when it is more expensive.

“Operators are looking at options to no longer tender for diesels trains,” Seeger says. “Most of them outside of Europe are at the start of that - they don’t know yet how big is the range of a battery-electric train or what is the range of a hydrogen train. There is still learning to do on alternative traction but the appetite and the willingness to go away from diesel is very, very big.”

“Germany is the first country to award big contracts for battery-electric trains, but I am sure that more will follow.”

Katrin Seeger

Seeger says the supplier is able to offer a variety of traction solutions to meet demand, whether this is running a hybrid solution of batteries and traditional electric traction where batteries have a range of 100-120km, or hydrogen fuel cells, which could operate for 600-1000km. Mr Brahim Soua, vice-president for regional trains at Alstom, offers similar estimates for its applications. He says that improvements in battery storage capability have helped to reduce the weight of the unit while the range of operation has gone up.

“The technologies are mature enough for many applications, it just depends on the model that the operator chooses,” Seeger says. “Germany is the first country to award big contracts for battery-electric trains, but I am sure that more will follow.”

Costs, though, remain a prohibitive factor for many. RMV’s contract for 27 Coradia iLints is worth approximately €500m with Alstom’s share €360m. This compares with the €150m deal with Transdev for 41 Lint DMUs. The contract for 11 BEMUs with Mid Saxony is worth €100m.

In addition, many of the German alternative traction projects have benefitted from government subsidies to get off the ground. The federal government’s National Innovation Programme for Hydrogen and Fuel Cell Technology, for example, provided a €8.4m grant to support the construction of the hydrogen refuelling station for the Coradia iLint project at Elbe-Weser Transport Company’s (EVB) depot in Bremervörde. While significantly cheaper than an equivalent electrification project it is a lot more expensive than using diesel.

Alternative traction

Seeger says the current gap in the cost of alternative traction is the result of a lack of economy of scale in the supply chain. As the technology becomes more widespread, she says this should correct itself. She adds that if these subsidies do disappear, the government could support the adoption of clean traction by enacting legislation restricting the operation of diesel trains in urban areas. “At the very least they could make them less attractive by introducing access charges depending on future emissions,” Seeger says. “Public transport companies could change their tender assessment scheme to reduce the gap as well.”

With subsidies not yet taking hold in other countries, demand for diesel rail vehicles is set to remain steady, particularly outside Europe.

The general consensus is for a stable market for the next 10-15 years with alternative traction currently accounting for less than 2% of all orders. According to data from IRJ Pro, seven such orders were placed in the past three years, all from Germany apart from a contract awarded to Stadler in the United States by San Bernardino County Transportation Authority for a single four-car Flirt H2 hydrogen train. Blassmann says the market could remain relatively stable for the next 30 years given the current uptake of electrification projects.

In addition, diesel technology itself is becoming much cleaner. New EU Stage V emissions standards, which apply to all new engines, are set to come into force on January 1 2021 and offer substantially improved performance over previous standards. Stage V engines limit particulate matters to 0.015g/kWh per rail car, a 40% reduction compared with the previous Stage IV emission limit of 0.025g/kWH. In some heavily polluted areas, the air that is emitted from a Stage V engine is cleaner than the surrounding atmosphere.

“There is a misunderstanding of how clean diesel engines now are,” says Dr-Ing Guenter Zitzler, senior manager application engineering rail engines at Rolls-Royce Power Systems. “We have done a study of replacing the UIC2 engines in trains running on the shore of Lake Constance with MTU hybrid powerpacks fitted with Stage V engines, and it was very impressive to see that there is a reduction in particulates of around 90% and also the NOx by 90%. The hybrid powerpacks also help to cut fuel consumption and thus CO₂ emissions by up to 25%.”

While these are European standards, suppliers are finding that countries where there are no regulations are requesting engines that meet these requirements.

Voith is now only offering its EU Stage IIIB or Stage V engines, all of which are fitted with Selective Catalytic Reduction (SCR) technology. “There is rising public awareness of emissions levels so that is why we want to promote the best possible diesel solution available in the market,” says Mr Gert Tekale, product manager for rail drives at Voith. “For current projects in Brazil we are bidding with Stage V engines and they like this even though there is no specific requirement.”

Voith has developed its Stage V engine in partnership with Liebherr. The supplier has agreed a five-year contract with Alstom to supply its RailPack 400DM Stage V-compliant powerpack for Coradia Lint DMUs. Tekale says Voith expects to begin endurance tests in the second half of this year ahead of commercial availability in 2021.

“We did a trial in Britain with Porterbrook (Southwestern Railway) where we replaced a hydro dynamic gearbox with our hydro mechanic gearbox and we saved more than 20% of fuel.”

Mr Markus Gross, ZF’s director for rail drive systems

Other innovations are also improving diesel engine efficiency. For example, ZF’s EcoWorld transmission system, which transfers the reversing unit previously installed in the bogie directly to the shifting transmission, can offer a coasting mode, disconnecting the engine from the traction system helping to cut fuel consumption by up to 5%. It also facilitates MTU hybrid system’s shift from engine to battery power.

ZF’s EcoWorld transmission system

Mr Markus Gross, ZF’s director for rail drive systems, says he sees significant potential for the technology along with stable demand for diesel products over the next 10-15 years. However, he says the supplier is not favouring one area over another. EcoWorld, the supplier’s latest six-speed transmission platform, is suitable for conventional diesel - ZF is a supplier to the Coradia Lint DMUs - and hybrid applications where it is working with MTU. ZF also supplied transmission to the Coradia iLint. Gross adds that there are significant opportunities in repowering existing diesel engines to improve their efficiency.

“We did a trial in Britain with Porterbrook (Southwestern Railway) where we replaced a hydro dynamic gearbox with our hydro mechanic gearbox and we saved more than 20% of fuel,” Gross says. “If you see the large numbers of diesel fleets in operation across the world, there is huge potential for repowering.”

“I personally cannot imagine, on a business perspective, that it makes sense to build up a third infrastructure.”

Mr Tim Boltken, technical managing director of Ineratec

Voith is also active in the hybrid field, offering diesel-electric gensets and sophisticated braking energy recuperation systems. However, Tekale says the desire of the major OEMs to develop hydrogen and BEMUs is potentially bad news for propulsion sub-suppliers as the trend is to take the development of batteries and hydrogen in-house.

“The more electrified vehicles become, the more it will become insourced by the OEM,” Tekale says. “If they are using a sophisticated diesel system, they do not have the complete expertise in-house. An electric propulsion system with batteries is less complex than a diesel system and they are insourcing that expertise.”

With this in mind, Voith and MTU are paying close attention to the development of alternatives to diesel fuel itself, which will potentially extend the life of the combustion engine and also use existing infrastructure.

Bio-fuels, where natural products such as ethanol are blended with diesel to help reduce diesel consumption and air pollution, have been around for decades. However, problems with the build-up of plaque on the engines due to the higher burning point of the fuel as well as the sustainability of these fuels, especially the use of palm oil in some areas and the link with deforestation, has restricted the extent to which they have been adopted.

Yet Blassmann believes these solutions have been overlooked for too long and is encouraged by work underway by start-ups on alternative fuel solutions which promise carbon neutrality. Ineratec is one such company founded in 2016 as a spinoff from Karlsruhe Institute of Technology (KIT).

The Ineratec technology essentially combines hydrogen and CO₂ through a process called Power-to-Liquid to produce a substitute fuel for gasoline, kerosene or liquid oil. The fuel is produced under the Power-to-X (or Power-to-liquid) principle whereby surplus power from renewable generation is used to power an eletrolyser to generate hydrogen, which is combined with CO₂ sourced from biomass, ambient air or industrial off-gas to produce the fuel via a chemical process called Fischer-Tropsch.

The end-product is a clear liquid, which burns very clear and when burnt releases the CO₂ introduced at the start of the process, making the production and use of the fuel entirely carbon neutral in that no additional CO₂ is released into the atmosphere. The diesel fuel fraction produced complies with the synthetic or paraffinic diesel norm EN15940, which was adopted in 2016, and stipulates that the fuel is acceptable by all existing diesel engines.

“It really looks like water because you only produce it from hydrogen and CO₂,” says Mr Tim Böltken, technical managing director of Ineratec. “There are no poisons such as sulphur or chlorine in there and equivalent fuels already exist such as the synthetic component of Shell Vpower, a high-performance fuel which is a blend of existing fossil fuel and synthetic fuel - but yet not renewable. You don’t have to substitute it 100% at the beginning. You can start with 5 or 10% and you will immediately achieve a 5 or 10% reduction in emissions.”

Böltken says the advantage of the Ineratec system is that it is modular. A single processing system using, for example, 1MW of electrical input into the electrolyser can produce 350 tonnes of fuel per year from just a single 40-foot shipping container. Customers are then able to easily scale up production depending on their requirements at a specific site by adding additional containers. Larger modules are also in development.

“In Germany we are building up a new infrastructure for electro mobility which costs billions, but we already have an existing infrastructure based on oil and gas,” Böltken says. “I personally cannot imagine, on a business perspective, that it makes sense to build up a third infrastructure.”


With oil prices plummeting in early 2020, synthetic diesel fuels face a challenge to become cost-competitive. Rather than the cost of oil, the price of electricity is the determining factor, with use in low electricity cost markets such as Norway, Chile, the Middle East and southern Spain preferable than a high energy market such as Germany.

However, the developers have made significant progress at reducing the cost of the process in recent years. From around €10 per litre when Tekale was first exposed to the concept at Karlsruhe Technical University around a decade ago, the cost is now equivalent to around €2 per litre.

“If we wait until 2030, then there is no way you will achieve the climate goals set for 2050.”

Tim Böltken

“If it comes down to €1.50 a litre, then it is competitive,” Tekale says. “Then operators might be willing to spend a little more money on fuel but get a better CO₂ footprint as a result.”

After completing several demonstrator projects to prove the viability of the concept, Böltken says Ineratec has reached the industrial scale demonstration stage. “We want to show that not only can these fuels be produced at a certain level of cost, they can also compete with fossil fuels,” Böltken says. “We are looking for our iPhone moment.”

Rail is by no means the only sector that could benefit from such an installation. Indeed, with scale still limited it may have a fight with aviation, road and chemical production if it is to secure the level of adoption required to make a difference.

Böltken says he is open to working with any sector or partner willing to embrace and develop the technology, ultimately leaving it to the market to decide. The excitement around Ineratec’s solution at events he has attended offers hope that such a partner will soon be found. However, time is ticking. “In the next five years this is really crucial, not only for our business model, but the whole climate issue,” he says. “If we wait until 2030, then there is no way you will achieve the climate goals set for 2050.”

There might just be life in the diesel traction market yet.