Above is the Russian Railway’s LNG-fuelled gas-turbine locomotive.

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Alternative fuel limitations

LNG is unlikely to be a practical proposition for rail passenger units. If used to power locomotives, it would require the train to be lengthened by an extra vehicle to carry the LNG tank.

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Hydrogen and battery technologies offer significant benefits, which will no doubt be developed further. However, their low energy densities will always be a significant constraint. For this reason, there is no prospect of self-powered rail traction using alternative fuels for high-power rail traction. Rail Freight Group executive director Maggie Simpson made this point in her response to Johnson’s statement. She noted that, whilst battery and hydrogen ‘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’. She advised that RFG would like to see the “continued affordable electrification of the strategic freight network”.

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Yet, in his call for the railway to decarbonise, Johnson expects that batteries and hydrogen will replace the diesel engines on bi-mode trains. His advisers would seem to be unaware of the fundamental constraints of these technologies. In his speech, Johnson also seemed to dismiss electrification by stating that it was “unlikely to be the most cost-effective way to secure these vital environmental benefits”.

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Zero-carbon electrification

Although Johnson’s expectation that greener alternatives will replace diesel is not unreasonable for lightly used lines, this aspiration is unrealistic for busy core routes that require high-powered traction. For these, electrification is the only option that offers the prospective of zero-carbon rail traction as an increasing proportion of Britain’s electricity becomes generated by renewals. The use of wind turbines to provide all the power for electrified railways in the Netherlands shows what can be done.

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Furthermore, busy electrified routes carry far more traffic than rural lines, and so offer far greater environmental benefits than alternative-fuelled self-powered vehicles.

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Whilst electrification’s high initial capital cost gives it a poor business case for rural routes, this is not the case for busy main lines. The economic case for electrification is recognised by many countries that have a high percentage of their rail network electrified. These include Netherlands (76 per cent), Italy (71 per cent) and Spain (61 per cent). In the UK, just 42 per cent of the network is electrified.

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Electrification offers improved passenger benefits with its greater acceleration and speed. For example, a bi-mode class 800/2 has a power to weight ratio of 11.2kW/tonne in electric mode and 6.9kW/tonne in diesel mode.

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Electrification also offers enormous operational cost savings. A recent report by the Office of Rail and Road (ORR) on rolling stock costs showed that, whilst the Virgin Trains fleet portfolio includes only 15 per cent diesel rolling stock, diesel accounts for 40 per cent of its total energy costs, making it around four times the cost of electric traction. One reason for this is that, unlike diesels, electric trains can absorb the huge amount of energy required to brake a train and regenerate it back into the grid.

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The high maintenance and capital cost of diesel trains is illustrated in a National Audit Office report that considered the procurement of Hitachi IEP bi-mode trains, which includes a 28-year maintenance contract. This showed that the Great Western IEPs, which frequently operate under diesel power, cost £4 million more per vehicle than the mostly all-electric East Coast IEPs.