Renfe in Spain will begin pilot tests this month of a two-car passenger train powered by liquefied natural gas (LNG) in what it says are the first such trials in Europe. A CAF train is being used for the tests, in which one of its two diesel engines has been replaced by an LNG powered engine, with the remaining diesel used as a comparator.

Researchers expect to identify the technical requirements for LNG traction during the trials, which will offer a clearer idea of the environmental implications and the potential use of LNG on non-electrified lines.

In Germany, Lower Saxony Transport Authority (LNVG) signed a contract with Alstom and gas supplier Linde Group on November 9 for 14 Coradia iLint hydrogen fuel multiple units - the first order for iLint, following its debut at InnoTrans last year. Linde will install dedicated hydrogen refuelling facilities for the trains, which will have a range of 1000km on a single tank of hydrogen.

Meanwhile, the EcoTrain project led by German Rail (DB) is harnessing lithium-ion battery technology as an alternative to diesel operation, while last year, eight German railway associations called for further development of new traction systems such as batteries, fuel cells and hybrid systems.

In addition, Ballard Power Systems has signed an agreement with Siemens to develop a 200kW fuel cell engine for Siemens’ Mireo multiple unit, with the first main line trials planned for 2021. Siemens Mobility CEO Mrs Sabrina Soussa described the deal as “a decisive step towards replacing diesel-powered rail vehicles with emission-free vehicles.”

Ballard is also working with CRRC Tangshan, China, on a hydrogen-powered LRV and trials began on a 14km light rail line in Tangshan in October.

In the Netherlands, Arriva has signed a contract with Stadler for 18 Wink multiple units, which will initially operate on biodiesel. The trains will have engines designed to use hydrogenated vegetable oil (HVO), with provision for conversion to battery and overhead electric operation.

But it is not only rail which is developing new types of traction. A new potential threat to rail comes from Tesla. Mr Elon Musk, its founder and chief executive, unveiled the company’s first electric lorry, the Semi, in Los Angeles on November 17. Musk claims the overall cost of ownership for the Semi will be 12% less per kilometre than for diesel vehicles. The Semi will be able to accelerate from 0-100km/h in 20 seconds with a payload of 36 tonnes compared with around 1 minute for a diesel lorry, and it will climb 5% gradients at 105km/h compared with about 70km/h for a diesel. Tesla says the Semi will be able to regenerate 98% of kinetic energy to the battery. The Semi will have a range of 800km, and Tesla says it plans to introduce rapid dc chargers that will produce a 640km charge in 30 minutes.

The Semi will have an enhanced autopilot as well as automatic emergency braking, automatic lane keeping, lane departure warning, and event recording. But Musk’s most important claim is that several Semis will be able to autonomously follow a lead Semi as a convoy which he says would make it cheaper to send freight by road rather than rail.

While electric trains have better performance than diesel trains, if the Semi becomes a commercial reality and lives up to expectations, it could make life more difficult for rail freight operators wedded to diesel traction such as those in North America.

Nevertheless, one US railway has just made the switch from diesel to LNG. Florida East Coast Railway (FECR) has become the first North American railway to adopt LNG for its entire mainline locomotive fleet following the modification of its fleet of 24 GE locomotives, which operate in pairs with a purpose-built fuel tender.

LNG has been tested as a locomotive fuel for 25 years in North America and is still under evaluation by several Class 1 railways including BNSF. FECR has switched from diesel to LNG because its mainline locomotive fleet is captive to the Jacksonville - Miami main line, and it has access to a ready source of LNG.

While adopting LNG would enable railways to move away from their polluting diesels, it is not the game changer that electric traction can offer in terms of tractive effort and efficiency. And an electrified railway can be powered by any fuel which makes it ideally placed to withstand future changes in fuel availability.

India’s railway minister, Mr Piyush Goyal, made a bold announcement on November 21 that Indian Railways will phase out mainline diesel locomotives within five years in favour of electric traction. While laudable, this appears unrealistic as only around one third of the 62,600km network is electrified and GE won a contract to build 1000 diesel locomotives just a year ago.

Electrification coupled with other innovations such as last-mile diesel-equipped electric locomotives, EMUs with batteries to take them beyond the wires, and dual-mode trains, demonstrate the increasing operational flexibility which is now available and will be one of the keys to success in the future.