Diesel locomotive

It’s been more than two centuries since Cornish engineer Richard Trevithick showed off his railway invention in the Welsh mining town of Merthyr Tydfil, changing the world in the process. By demonstrating the first operational railway steam locomotive, Trevithick set the stage for a transport revolution, the flame of which was fanned by the Industrial Revolution and propelled through the 20th century by new fuel sources and a growing concern for efficiency and environmental performance.

From the most primitive steam engines of the early 19th century to the advanced propulsion concepts that have yet to be fully explored today, we present a timeline through the past, present and near-future of locomotive development.

1804: Trevithick kicks off the age of steam power

Before his big rail breakthrough in 1804, British mining engineer, inventor and explorer Richard Trevithick had been working on high-pressure steam engines for several years with mixed results, from the successful demonstration of the ‘Puffing Devil’ steam-powered road locomotive in 1802 to disaster in Greenwich in 1803, when four men were killed by an explosion of one of Trevithick’s stationary pumping engines. Trevithick’s rivals used the incident to argue the risks of high-pressure steam.

Nevertheless, Trevithick’s ‘Penydarren locomotive’, secured a central place in the history of locomotive technology when it became the first full-scale working railway steam locomotive. The key demonstration of the locomotive was prompted, strangely enough, by a bet. Trevithick’s benefactor and owner of the Penydarren Ironworks, Samuel Homfray, placed a wager for 500 guineas with iron merchant Richard Crawshay that Trevithick’s locomotive – adapted from a stationary steam engine being used to drive a hammer at the ironworks – could haul ten tonnes of iron from the Penydarren Ironworks to the village of Abercynon nearly ten miles away.

On 21 February 1804, Trevithick’s locomotive made the journey in just over four hours, winning Homfray the bet and vindicating the high-pressure steam concept. Shortly after, the engine was returned to its original stationary role at the ironworks. Trevithick never received the recognition he deserved for his pioneering role in railway locomotion, and died destitute and forgotten in 1833. His work was publicly recognised in 2004 – the bicentenary of his feted demonstration – by the Royal Mint, which released a commemorative £2 coin bearing his name and his invention.

1812-1848: moving steam forward

From the humble beginnings of Trevithick’s Penydarren locomotive, steam-powered rail transport gradually built momentum in Britain through the first half of the 19th century, with subsequent innovators building on the foundation he set. Matthew Murray proved the commercial viability of steam locomotion in 1812 with Salamanca, a locomotive named after the Duke of Wellington’s 1812 victory in the battle of the same name. Salamanca, which was built to run on the Middleton Railway, was the first locomotive to incorporate two cylinders and the first to use the rack and pinion linear actuator to convert rotational motion into forward momentum.

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It is George Stephenson, however, who has risen above all other steam locomotive innovators to become known as the father of railways and one of the pre-eminent engineers and designers of the Victorian era. Inspired by the work of Trevithick and Murray, Stephenson is said to have built 16 experimental locomotives for use at the Killingworth Colliery between 1814 and 1826, starting with Blücher – another locomotive name with its origins in the Napoleonic Wars – and culminating with the Killingworth Billy, which ran on the Killingworth Railway until 1881.

Stephenson would go on to build the world’s first steam-powered intercity railway line between Liverpool and Manchester, which opened in 1830 and kicked off the steam train revolution in earnest. By the time Stephenson died in 1848, having established his company as the leading builder of railways in the UK, US and continental Europe, Britain alone was criss-crossed by 2,440 miles of railway supporting 30 million passengers.

1879: electrifying the railways

Germany was a hub of electric locomotive development in the late 19th century, with the first experimental electric passenger train demonstrated by Werner von Siemens, inventor and founder of multinational engineering company Siemens AG, in 1879. The train, which established the concept of the insulated third rail to supply electricity, transported a total of 90,000 passengers around a circular track over a four-month period

Siemens went on to build the world’s first electric tram line in the Berlin suburb of Lichterfelde in 1881, setting the stage for the likes of Volk’s Electric Railway in Brighton and the Mödling & Hinterbrühl Tram in Vienna, which both opened in 1883.

The need for less polluting trains in underground subways and tunnels drove the adoption of electric locomotives in the decades to follow, while the improved efficiency and simpler manufacturing brought about by the introduction of alternating current made electric trains feasible on longer lines and steeper sections of track. Hungarian engineer Kálmán Kandó was instrumental in the development of longer-distance electrified lines, including the 106km Valtellina railway in Italy.

Today, electric locomotives continue to play an important role in the rail landscape through high-speed services like the French TGV, Japanese Shinkansen and Acela Express in the US. However, the high cost of electrifying lines to power electric locomotives, either by third rail or overhead catenary, continues to be an obstacle to wider deployment of the technology.

1892 – 1945: the dieselisation process

Dr Rudolf Diesel’s original patent on his compression ignition engine (or diesel engine) in 1892 quickly prompted speculation on how this new internal combustion method might apply to railway propulsion. While it would take several decades before the benefits of diesel could be properly realised on rail locomotives, the ongoing development of increasingly efficient diesel engines with improved power-to-weight ratios in the late 19th and early 20th centuries – many of which originated at Swiss engineering firm Sulzer, at which Rudolph Diesel worked for several years – put diesel on track to make steam locomotion virtually obsolete by the end of the Second World War in 1945, with steam locomotives exceedingly rare in developed countries by the late ’60s.

The relative standardisation of diesel engines when compared to steam provided better economies of scale in mass manufacturing, while diesel locomotives offered many clear operational advantages, including multiple-locomotive operation, cheaper maintenance and idling time, better thermal efficiency and less labour-intensive operation.

1945-present: the rise of diesel-electric

Once diesel’s dominance over steam was assured, the post-war period was filled with ideas and concepts for improving rail propulsion, with each achieving mixed success. Among the more hare-brained schemes was hatched by Utah University’s Dr Lyle Borst in the early ’50s – the nuclear-electric train. Even discounting the endless safety and security implications of carting a 200-tonne nuclear reactor across the countryside at high speeds, the cost of manufacturing locomotive reactors and buying the uranium to fuel them soon put paid to the idea of trains joining the atomic age.

While other more realistic concepts, such as gas turbine-electric locomotives, gained traction to certain extents during the post-war period, diesel remains king to this day. Out of the three common power transmission systems tested for use with diesel engines – hydraulic, electric and mechanical – by this time it was clear that diesel-electric had become the new standard in the field. Of the three systems, diesel-electric locos – in which a diesel engine drives a DC or AC generator, which then powers the traction motors – have received by far the most development in the second half of the 20th century and represent the majority of diesel locomotives in service today.

Diesel-electric locomotives have also set the stage for new, modern locomotion systems that responded to environmental concerns that had begun to surface in the late 20th century and dominate rail propulsion discussions today. Hybrid trains, for example, add a rechargeable energy storage system (RESS) to the diesel-electric process, which allows trains, including many built under the UK’s Intercity Express project and scheduled to come into service in 2017, to charge an onboard battery using energy derived from regenerative braking.

21st century trends: LNG and hydrail

Diesel has fuelled the growth of railway systems around the world for the better part of a century, but in the 21st century the environmental impact of diesel train operations – which include the emission of greenhouse gases as well as harmful emissions like nitrogen oxides (NOx) and particulates – has led to the development of more eco-friendly locomotive technologies, some of which are in operation while others remain just over the horizon.

The shale gas revolution that is ongoing in the US and beginning to pick up speed elsewhere in the world has prompted greater attention on the potential of liquefied natural gas (LNG) as a railway propulsion fuel. With LNG priced significantly lower than diesel and promising 30% fewer carbon emissions and a 70% cut in NOx, it’s advantageous both financially and environmentally, and several major freight operators including Canadian National Railway and BNSF Railway have been trialling LNG locomotives in recent years with a view to making the switch where appropriate. Regulatory and logistical issues remain, but if the fuel price incentive remains high, it is likely these will be overcome.

LNG might involve some emissions reduction, but it still ties the industry into the hydrocarbon economy even as the scientific consensus warns that the world must begin the transition into a post-carbon future now to avoid dangerous climate change. Hydrail, a new locomotive concept that involves using sustainable hydrogen fuel cells instead of diesel engines, emits nothing but water at the point of operation. Hydrogen can be produced from by low-carbon energy sources like wind and nuclear. Hydrail prototype projects have been carried out by an active research community in countries like the UK, US, Japan, Denmark and South Africa, while the tiny Dutch island of Aruba is planning to debut the world’s first hydrogen tram fleet for its capital Oranjestad. A small start, perhaps, but according to prominent hydrogen economy advocate Stan Thompson, hydrail “is likely to be the world’s dominant railway propulsion technology” by 2050, so it may yet prove the clean tech innovation to finally knock diesel locomotion off its perch.

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