Pollution from diesel engines has been much in the news. Twenty years ago the Government advised the use of diesel rather than petrol in cars because of its lower CO2 emissions, but overlooked more sinister elements of diesel exhaust, thinking that filters removed the problem.
Diesel has long been the preferred fuel for larger vehicles, especially those doing considerable mileages, on grounds of economy. Sixty years ago London Transport carried out a study of the effect of diesel exhaust on its garage staff, but concluded that it was not especially harmful.
Recent concentration has been on the reduction of exhaust by the development of hybrid vehicles, where the engine is used to generate electricity to propel the vehicle as it accelerates.
The new standard bus for London is a refinement of the hybrid principle and is replacing diesels — 600 will be on the road next year. It is 15 per cent more fuel efficient than existing hybrids, but 60 per cent more expensive. This is regarded as a stepping stone to wholly electric vehicles, the key to which is the development of battery technology.
There are 12 wholly electric single-deck buses in York, and a similar number in London. They had to be single-deck because batteries had to be carried on the roof, but the Chinese have developed more compact, efficient batteries, enabling them to produce a prototype double-deck bus for London. The aim is to rid central London of diesel buses by 2020, and gradually other cities will follow. Buses do not have a very long life so we can expect to see hybrid buses being cascaded to areas such as Northumberland within a few years.
National Rail experimented with a hybrid locomotive, which was successful, but it has not been pursued, and full electrification is to be carried forward. The two main lines from London to Scotland have been electrified for some time, and the central belt of Scotland is being electrified now, as are the Great Western, Midland mainline and the Trans-Pennine route.
The last of these is a demonstration of how things can go wrong when politicians set impossible time and budgetary constraints. Things do not always come out right, as in the case of the Borders Railway, where the need to complete on time and on budget led to inadequacies, which will cause huge disruption and cost to put right.
On electrification, power is normally supplied through overhead wiring, the cost of which would be saved if the hybrid principle had been pursued, but this requires diesel engines to top-up batteries. Diesel power is still going to be required for lines which are not going to be electrified, and diesel fuel is going to become scarcer and more expensive.
The alternative is more efficient, smaller and lighter batteries, which have not yet been developed with sufficient power for normal railway use, but battery trains are being developed for branch lines. If batteries are used, mains power is still required to re-charge them. Discussion of electric power for transport leads to the question of power generation.
Politicians have committed to the construction of a nuclear power station and the provision of power at a high cost. It is to be built on the banks of the Severn estuary, which has one of the strongest tidal flows in the world. Proposals have been made to harness this power by the construction of a Severn Barrage, but the disturbance to wildlife has led to no further action. It has been calculated that it could power the electrification of the Great Western railway. Environmentalists question the wisdom of the construction of nuclear power stations and ‘fracking’ in an island surrounded by powerful tides.
John Wylde is the author of ‘Integrated Transport – a Will-o’-the-wisp?’ This book is priced £14.95, post paid and signed. Also ‘Experiments in Public Transport Operation’ at £11.95. Order at www.john-wylde.co.uk