Looking to the future
Pollutants from rail diesel traction may soon become increasingly unacceptable. In California, a study has shown that the nitrous oxide emissions from diesel locomotives hauling freight trains from the ports of Los Angeles is equal to that from all Southern California’s industrial plants. In the USA and Europe, emissions standards for railway diesel traction are more relaxed than those for lorries and buses on the basis that railway emissions are low per tonne hauled. This may change with increasing concern about total emissions.
For example, Canada’s fleet of 3,000 locomotives consumes two billion tonnes of diesel to produce six million tonnes of CO2 and 100 thousand tonnes of pollutants that are hazardous to health. This is one of the reasons why Transport Canada has funded a study into the feasibility of using Hydrail vehicles for commuter trains in Ottawa and Toronto.
A hydrogen powered main line locomotive would require a fuel storage arrange similar to this Russian LNG powered gas turbine locomotive.
In Toronto, such trains are hauled by diesel locomotives of 3,000kW, which is far greater than the power of any hydrogen powered rail vehicles to date. Initial feasibility work shows that a hydrogen-powered locomotive with this output would have to be a two-unit locomotive with one unit containing only the hydrogen storage. Such a hydrogen locomotive would thus need the train to be extended by another coach length, or require a passenger coach to be removed from the train.
This indicates that the space required to store hydrogen is such that its use to fuel freight locomotives or high-speed trains may not be viable. For high-powered rail traction applications, electrification is likely to remain the only non-polluting, low-carbon option, dependant on how electricity is produced. For lower-powered applications, such as shunting locomotives and multiple units, it will be difficult to persuade legislators to continue to accept higher emissions from railway diesels when hydrogen offers a zero-emissions alternative.