Dieselisation

Dieselisation or dieselization is a term generally used for the increasingly common use of diesel fuel in vehicles, as opposed to gasoline or steam engines.

The two-stroke marine diesel engine was introduced in 1922 and remains in use today. It is the most efficient prime mover, with models over 100,000 horsepower and a thermal efficiency of 50%. The market share of steam ships peaked around 1925 (a few sailing ships remained) and by the early 1950s diesel ships held over 50% of the market.

In rail transport, dieselisation refers to the replacement of the steam locomotive or electric locomotive with the diesel-electric locomotive (often referred to as a "diesel locomotive"), a process which began in the 1930s and is now substantially complete in the US, UK and Latin America. Elsewhere, electric traction has mostly taken the place of steam locomotives in the main lines and diesel-electric and diesel-hydraulic locomotives are used in less frequently used side lines.

The replacement of either steam or diesel haulage with electric locomotives is known as electrification. Whereas the benefit of replacing steam traction is indisputable, there is some dispute as to whether it is best replaced by dieselisation or electrification. Electrification has a high initial capital cost but the operating costs are lower. The overall savings depend on the effect of the investment cost compared with the savings due to lower operational and maintenance costs and the influence of better acceleration and tractive effort on railroad throughput. These are obviously different for e.g. urban networks and very long-distance networks with low frequencies. However, many railway commentators are increasingly suggesting that the ability of railways to operate with electricity not produced from fossil fuels may offer a decisive advantage over diesel power. In some countries, such as Switzerland, Sweden, Poland and Japan, electrification ended the use of steam power.

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