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Fuel cells set to switch trains onto a greener track
20 March 2007
From New Scientist Print Edition.

Julia Pierce
Fuel cell Railcar

Later this year, a small grey railcar will wind its way through the Yatsugatake mountain range in central Japan. Between Kobuchizawa and Komoro it will pass the highest point on Japanese railways. There the grandeur of its surroundings will be matched by the ambition of the little train's designers - nothing less than to transform the environmental impact of rail transportation.

That is because a successful journey will make the railcar the first hydrogen-fuelled train to travel on a regular passenger track anywhere in the world. Powered by fuel cells running on hydrogen from its tanks and oxygen from the air, the train will emit only a few gentle puffs of steam as it travels. "This is a clean system where only water is discharged," says Hiroyuki Sawada of East Japan Railway, which developed the railcar. "There is no direct discharge of carbon dioxide, nitrogen oxide or particulates."

East Japan Railway hopes the planned journey will put it ahead of a rival project being mounted by the Railway Technical Research Institute (RTRI), also based in Tokyo, to build a hydrogen-powered passenger train. Not only in Japan, but in the US and Europe too, the race is on to find ways of cutting emissions from trains by replacing diesel engines with less-polluting hydrogen fuel cells. Canada recently announced plans to build a hydrogen-powered passenger train, possibly in time for the Winter Olympics in 2010.

Although existing techniques for producing hydrogen, such as natural gas reforming (see "Caught in the carbon trap"), themselves produce carbon dioxide, hopes are high that moving from diesel to hydrogen power will still cut overall emissions. In the UK, figures produced by the Rail Safety and Standards Board, a non-profit industry body that also undertakes research, suggest that replacing diesel trains with fuel cell powered trains could cut railways' carbon dioxide emissions by a quarter.

As well as the environmental benefits, fuel cell powered trains have other advantages. They are as quiet and vibration-free as electric trains, and so cause less disturbance than diesels in built-up areas. Yet unlike electric trains, they don't need any trackside infrastructure, such as overhead cables and masts, and electricity substations. This is a significant benefit in a densely populated country like Japan, Sawada points out. "We can make more effective use of space around the tracks such as construction of buildings above the railway and lower bridges," he says.

The railcar East Japan Railway will be using for the test is fitted with two 65-kilowatt polymer electrolyte membrane fuel cells and a 19-kilowatt-hour lithium ion battery to provide additional power on steep gradients or when accelerating. To help keep the battery topped up, the vehicle is fitted with a regenerative braking system; this is a well-established technology in which the train's electric motors double as brakes that slow it down by converting its kinetic energy into electricity.

The power output of the system is low compared to the 300-kilowatt engines typical of modern diesel commuter trains, but it's still enough to propel the railcar at up to 80 kilometres per hour on a level track. As yet, though, it can only run for 80 kilometres before it needs refuelling. The company is not predicting when the railcar will be ready to enter regular passenger service.

Though East Japan expects to be the first to run a fuel cell train on an ordinary track, the rival project from RTRI is not far behind. In October 2006 the company, whose project is part-funded by Japan's Ministry of Land, Infrastructure and Transport, completed a successful trial on a test line of a prototype vehicle powered by a 120-kilowatt fuel cell. By the end of this year the company expects to have built and tested its own train, in which the fuel cell is backed up by a battery, as in East Japan's vehicle. The fuel cell unit is currently with its developer Nuvera Fuel Cells in Cambridge, Massachusetts, for modification ahead of further tests.

The development of RTRI's train was originally managed by an American company, Vehicle Projects of Denver, Colorado, which is also developing a fuel cell locomotive for the US army and a consortium of rail companies. The locomotive, designed to shunt freight cars around rail yards, will be powered by a 250-kilowatt fuel cell. "It should have plenty of power," says Arnold Miller, president of Vehicle Projects.

The locomotive is being developed as part of a Department of Defense programme that funds technologies equally suited to military or civilian use, and is due to be completed by the end of this year. The army wants it to be able to double as a mobile power unit that could, for example, provide emergency power to a military base if the regular supply is knocked out. It could also be used in the aftermath of floods or earthquakes, hauling in supplies and then staying on site to power local hospitals and relief centres.

Further behind, the European Union is drafting plans to invest ¬245 million in a hydrogen rail research project due to start this year, says Carlos Navas, chief technology officer at Spanish fuel cell company NTDA Energía. If given the go-ahead, the project will form part of a wider European initiative to investigate the use of hydrogen and fuel cells. In the meantime, a European consortium including Network Rail, which manages the British rail infrastructure, and companies such as NTDA Energía, is planning to build prototype hydrogen trains to assess the feasibility of the technologies.

There are still many hurdles to overcome before hydrogen trains are a regular sight on the world's railways, not least reducing the existing high cost of manufacturing fuel cells and developing a cheap way to generate hydrogen that does not itself contribute to carbon emissions. Despite these problems, trains could be simpler to switch over to hydrogen power than cars and trucks. There is more space for a fuel cell and a bulky hydrogen tank in a large railway locomotive than in a small car. Also, establishing a network of refuelling stations should be simpler for trains than for cars and trucks, as trains are routinely refuelled in just a few depots, whereas road vehicles will need a much more extensive network of filling stations.

Given the growing global interest in building hydrogen trains, it is likely the Japanese rail trials will be the first of many. When the little grey railcar begins its journey through the mountains a few months from now, it may bring us a step closer to a new generation of clean steam trains.

From issue 2595 of New Scientist magazine, 20 March 2007, page 30-31

Caught in the carbon trap

Despite hydrogen's potential as a green fuel of the future, finding a cheap way to produce it without emitting greenhouse gases remains a challenge.

At present, most hydrogen is produced from natural gas in a process called steam reforming. The gas is combined with steam in the presence of a nickel catalyst to produce hydrogen - along with carbon monoxide and carbon dioxide. Both East Japan Railway and the Railway Technical Research Institute will use hydrogen produced in this way for their fuel cell trains.

In principle it is possible to produce hydrogen without adding to the carbon in the atmosphere, by using electricity from renewable energy sources such as wind turbines to split water molecules. This, however, is more expensive.

Some researchers are also hoping biology can provide the answer. Tasios Melis of the University of California, Berkeley, is investigating the idea of creating "farms" of reactors containing the green alga Chlamydomonas reinhardtii, which produces hydrogen as a by-product of photosynthesis (New Scientist, 25 February 2006, p 37). So far, his algae convert the energy of sunlight into hydrogen with an efficiency of only 1 per cent, but by genetically engineering them he hopes to increase this to 7 per cent within seven years. "My estimates are that when the yields grow up to that level, we could produce hydrogen competitively with natural gas reformation," he says.

He is combining his alga-based bioreactors with others containing the bacterium Rhodospirillum rubrum, which also produces hydrogen through photosynthesis. Unlike the algae, the bacteria can absorb light in the near infrared range, extending the proportion of the sunlight's energy his biofarm could convert into hydrogen.

Additional reporting by Helen Knight

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