Several efforts are underway to cut the carbon footprint of railways. The first stop was to build overhead traction over several hundreds of thousands of kilometers. However, this is an expensive business and several low density lines remained on diesel traction due to the high cost of electrification. With increasing environmental consciousness railways around the world started looking at alternatives to diesel. Battery EV did not suit the bill due to the range limitations as trains are invariably long distance mode of transport. In comes the hydrogen fuel cell which is environmentally friendly, can be refueled as quickly as a diesel locomotive and can carry as much fuel (hydrogen) as a diesel locomotive.
Recently the Japanese Railway Technical Research Institute has started the test run of a hybrid electric-battery-fuel cell multiple unit. The rake is a converted 1500 V DC EMU which comprises a 34 ton motor cars and a 29 ton trailer. Each 19.76 m long and 2.95 m wide car is fitted with two under body polymer electrolyte fuel cells housed in a module which is 2.60 m long, 2.655 m wide and 0.72 m high and weighs 1.9 tons. These fuel cells are connected to four high pressure hydrogen tanks carrying 180 litres of Hydrogen at 35 Pa. This fuel cell provides a range of 72 km.
In addition, the EMU is also installed with a new design 540 KW Li-ion battery pack which is 20% smaller but has 50% more energy density than a conventional Li-Ion battery. The train has three modes of operation:-
- 1500 V DC traction when an overhead traction supply is available.
- Fuel Cell mode when the two fuel cells generate 90KW of power each at between 200 to 350 V which is stepped up to 700 V to charge the batteries which in turn is stepped up to 1500 V for the traction motor.
- Battery only mode when the output from the battery is stepped up to 1500 V to run the EMU.