The Anonymous Widower

RTRI Tests Fuel Cell Multiple Unit

The title of this post is the same as that of this article on Railway Gazette.

This is the first two paragraphs.

JAPAN: Railway Technical Research Institute has started test running with a prototype multiple-unit which can work as a conventional or battery EMU or using a fuel cell powerpack.

Converted from an older 1·5 kV DC EMU, the test train comprises a 34 tonne motor car and 29 tonne trailer vehicle. Each car is 19 760 mm long and 2 950 mm wide. It is able to operate as a conventional EMU when running under overhead catenary, or as a battery unit off-wire, with or without the fuel cell in use to trickle-charge the batteries.

These are my thoughts.

The Hydrogen Fuel Cells.

The article says this about the hydrogen fuel cells.

Two polymer electrolyte fuel cells are contained in an underfloor module 2 600 mm long, 2 655 mm wide and 720 mm high, which weighs 1·9 tonnes.

The fuel cells are stated to have a rating of 90 kW at 200 to 350 V.

To get a handle on how powerful the hydrogen fuel cells are, these are some characteristics of a British Rail Class 456 train.

  • It is a two-car electric multiple unit.
  • It weighs 72.5 tonnes.
  • It has an operating speed of 75 mph.
  • It is a 750 VDC train.
  • It has a power output of 373 kW

I wouldn’t think that the two trains are that far apart in performance and capacity.

The Japanese train has a total power output from the fuel cells of 180 kW, but it can also use power from the battery.

I wouldn’t be surprised to find out that the Japanese fuel cell and battery combination was powerful enough to power the British train.

I also think, they would fit underneath a typical British train like the Class 456 train, which has a width of 2800 mm.

The Hydrogen Tanks

The article says this about the hydrogen tanks and the range.

Hydrogen is stored in four high pressure cylinders at 35 MPa, with a capacity of 180 litres, giving a range of 72 km.

The mass of the hydrogen in the tank according to this calculator on the Internet is around 4.3 Kg.

In How Much Energy Can Extracted From a Kilogram Of Hydrogen?, I showed that a typical fuel cell can produce 16 kWh from a kilogram of hydrogen.

So the hydrogen tank can be considered a battery holding 4.3 * 16 = 68.8 kWh.

That doesn’t sound much, so perhaps the capacity figure is for a single tank. In that case the total for the train would be 275.2 kWh, which seems more in line with the battery size of Vivarail’s two-car battery prototype, which has 424 kWh.

Each tank would be something like 2500 mm long and 300 mm in diameter, if they were cylindrical. Double the diameter to 600 mm and the capacity would be over 700 litres.

The Battery

The article says the train has a 540 kW battery, which I think could be a misprint, as it would more likely be 540 kWh.

Performance

The article says this about the performance.

The four 95 kW traction motors provide a maximum acceleration of 0·7 m/s2, and an electric braking rate of 0·86 m/s2

It also says that the range is 72 km.

My observations on the performance and traction system are.

  • The traction power of the two-car Japanese train at 380 kW is very similar to the 373 kW of the similar-sized British Class 456 train
  • The acceleration rate is very typical of an electric multiple unit.
  • Braking is regenerative and used to charge the batteries. As it should!

This leads me to conclude, that this is a train, that could run a short public service, just as the Class 379 BEMU demonstrator did in 2015.

Thoughts About Range

The range is quoted at 72 kilometres (forty five miles.) This figure is unusual in that it is very precise, so perhaps it’s the Japanese way to give an exact figure, whereas we might say around or over seventy kilometres.

Applying my trusty formula of three kWh per vehicle-mile for cruising gives a energy requirement of 270 kWh for the full range, which is close to the four-tank energy capacity of 275.2 kWh.

Comparison With Alstom’s Breeze

Alstom are building a hydsrogen-powered version of a Class 321 train, which they have named Breeze.

Like the Japanese train, this is a effectively two-car train with respect to capacity as large hydrogen tanks to give a thousand kilometre range are installed.

So do the developers of both trains feel that a hydrogen-powered train to replace two- and three-car diesel multiple units is the highest priority?

Conclusion

If nothing else, it seems the Japanese have designed a two-car electric multiple unit, that has the following characteristics.

  • Practical size of two-cars.
  • Most equipment underneath the train.
  • Useful range.
  • Acceleration and braking in line with modern units.
  • Regenerative braking.
  • Ability to work on overhead, battery and hydrogen power.

I am led to the conclusion, that once their research is finished, the Japanese could design a very practical hydrogen-powered train for production in the required numbers.

 

 

 

September 7, 2019 - Posted by | Transport | , , , ,

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