Renewable railway

The drive to make rail travel more environmentally friendly is gathering momentum. Earlier this year the UK launched the first European trials of a biodiesel fuel blend in scheduled passenger services.

Virgin Trains, which is trying it out in one of its Voyager sets, makes great claims for its environmental credentials. If the fuel is a success, says the company, it will be able to reduce the amount of CO₂sent into the atmosphere by 34,500 tonnes a year, ‘the equivalent of taking 23,000 cars off the road’.

Virgin, not a company known for mistaking the way the wind is blowing, has spotted the commercial value of greener trains for the industry (even though biodiesel carries a much higher duty than that paid by the rail industry for ordinary diesel).

A combination of EU legislation, consumer pressure and the possibilities offered by new technologies is shunting the rail industry towards greater efficiency, sustainability and generally reducing its impact on the environment.

One of the most prominent examples of the trend is the Oslo Metro, a three-car electric passenger train, designed and manufactured by Siemens Transportation Systems.

The train is sold heavily on its environmental performance, and is promoted in an extensive, glossy brochure dedicated solely to explaining, in layman’s terms, its green vital statistics. Siemens claims to be committed to meeting the demands of commerce ‘in an ecologically and socially sound manner’.

In the case of the Oslo Metro it is difficult to think of anything more it could have done, apart from making the whole train biodegradable.

The product’s key environmental performance indicators are broken down in great detail, starting with the fundamentals such as material consumption over the train’s entire lifecycle. This takes account of the total weight of materials used to build it (223,662kg), minus the amount that can eventually be recycled (151,485kg) to give a final, absolute consumption total of 72,177kg. The figures are intriguingly precise and, on face value, highly impressive.

The company has also computed the potential contribution of each three-car unit to global warming, which it puts at 2g of CO₂-equivalent per km during use and maintenance, rising to 2.6g for the entire lifecycle. These are stunningly small numbers in which to be talking about greenhouse gas emissions and global warming. Multiplied over the train’s 30-year life, at an estimated 120,000km a year they seem a bit more significant, but the values are still low. The company attributes them to the train’s high energy efficiency and the Norwegian energy generation mix, a large proportion of which is derived from renewables.

Siemens has also devised a programme for recycling and disposal, which claims a total recycling rate of 94.7 per cent. This has been achieved through materials that give a recycling rate of 84.7 per cent and a thermal recycling rate of 10 per cent.

According to Dr Joachim Stark, of Siemens Transportation, the company is responding to a combination of commercial, social and legal forces to develop a product that it believes potential customers across the globe will eventually come to see as offering a competitive advantage.

‘Due to EU regulations certain materials are no longer allowed, but the requirements of society also play an important role in the design of a vehicle. The environmental awareness of the public has been raised dramatically in the last few years. Some years ago the expression ‘carbon footprint’ was not common at all. Now everybody uses it.

‘All these points together were the reason Siemens developed such environmentally-friendly trains. The market is worldwide. One has to say that the focus on green products is not that important in, for example, China right now, but we are sure that within the next few years this will change.’

Beyond the commercial potential for the technology, Stark also claimed a more altruistic motive. ‘The environmental product declaration — the document which describes our environmental performance — was published to present to the public what we do and what we can do to preserve the resources and the environment. Of course, Siemens has to have an economic success as well, but the work was not done for commercial reasons.’

Siemens was contracted to build 63 train sets for Oslo, with delivery starting by the end of 2005. The complete train design was developed and co-ordinated by the Porsche Design Studio and manufactured at Siemens’ Vienna plant. Each train, which is designed for metro operation, consists of three aluminium motor cars, while the traction systems consist of self-ventilated and open-circuit air-cooled asynchronous motors. These are powered by a modern force ventilated IGBT compact inverter. Each three-car set is capable of carrying 678 passengers.

The product was conceived with its impact on the environment through its entire lifecycle in mind. Siemens claims that all the materials were chosen with regard to minimising environmental impact.

The company’s assessment even covers the extraction of natural resources by suppliers, as well as transport to processing sites and the production of raw materials.

The train is lightweight with modular design components. To reduce weight, extrusion aluminium profiles were used for the car body, while finite element calculations also helped optimise weight.

Siemens has also made a study of the energy required for assembly and production. In addition, the packaging materials of supplier products, internal production transport and the recycling or disposal of resulting materials is considered.

Finally, every aspect of the design and operation of the train is aimed at achieving high-energy efficiency, said Stark.

In terms of systems engineering, this rule governed the selection of individual components. ‘To increase energy efficiency, each component was selected with regard to its individual energy consumption and power loss. The same is true for the traction motors: high-efficiency level means lower losses for regenerating electrical power out of the kinetic energy of the moving mass of the train. Siemens traction motors are designed for high efficiency levels.’

In operation, the train achieves high efficiency using regenerative braking, which recovers 46 per cent of the energy consumed. Across the fleet of trains this offers significant benefits to the operator through reducing demand on the electrical supply. ‘The operation of the trains has to be organised, to utilise regenerated energy; for example, when one train accelerates and at the same time another train brakes, there is minimum need for additional power, thus saving primary electrical energy.’

Let us hope that the Oslo commuters, reassured that their journeys are doing as little as possible to destroy the planet, spare a thought for their UK counterparts, few of whom feel inclined to worry about the carbon footprint of their rail service.

As commuters in this country pour off the late 7.53am to Victoria will they see, somewhere further down the line, a twinkling signal turn to green and another new rail future begin its slow approach?