How a hydrogen train works and its application in India

The protons pass through the membrane, while the electrons are forced to travel through an external circuit. This flow of electrons generates electricity, which powers the train's traction motors. On the opposite side of the fuel cell, the protons, electrons, and oxygen recombine to form water, releasing heat. Thus, the direct results are electricity, water vapor, and heat, eliminating smoke and carbon dioxide emissions during operation.

Hydrogen sources and environmental impact

However, the environmental picture is not limited to this. On Earth, hydrogen is usually bound with other elements and is found in water, natural gas, and biomass, so it needs to be separated before use. One method is electrolysis, where an electrolyzer uses electricity to split water into hydrogen and oxygen. If renewable energy sources such as solar or wind are used for this, the resulting fuel is called green hydrogen.

If the electricity comes from coal or gas, or if hydrogen is extracted from natural gas without capturing the resulting carbon, the fuel can still have a significant carbon footprint. Therefore, the hydrogen train is best described as having zero direct, or 'exhaust,' emissions. The overall level of emissions depends on how the hydrogen is produced, compressed, transported, and stored.

Advantages and limitations of use

There is also an efficiency trade-off. Electricity can be supplied directly via overhead lines to power an electric train. When using hydrogen, the electricity is first spent on producing the fuel, which is then compressed, stored, and converted back into electricity onboard. Energy is lost at each stage.

Nevertheless, the hydrogen train can operate on existing tracks without the constant laying of overhead lines. This makes it useful for remote, historic, mountainous, or lightly used routes where installing and maintaining electrical infrastructure might be uneconomical. This is why hydrogen trains are unlikely to replace traditional electric units across all of India, as over 99% of the country's railway network is already electrified. The role of hydrogen will likely be to replace diesel on select sections that are difficult to electrify.

Train operation in India

The ten-car train consists of eight passenger coaches and two hydrogen-powered power cars located at the ends. Together, they provide a power output of 2400 kW. Hydrogen is stored in specially designed cylinders at a pressure of 350 bar. The fuel cells supply electricity supported by lithium iron phosphate batteries. The batteries compensate for sudden changes in consumption and allow the fuel cell system to operate stably.

Storage challenges and infrastructure

Storing hydrogen is difficult because it contains a lot of energy by mass but very little by volume at normal pressure. To transport a sufficient amount of fuel, it must be compressed, liquefied at extremely low temperatures, or stored using other specialized methods. The train in India uses compressed hydrogen, which requires robust cylinders, special valves and pipelines, as well as controlled replenishment and continuous monitoring.

Hydrogen is flammable, colorless, and odorless. Its flame can be faint and hard to detect. A leak in an enclosed space can create a serious fire risk. Indian Railways states that the train is equipped with leak, flame, and smoke detectors, ventilation, automatic shutdown systems, and fire protection equipment. Production, storage, and refueling must be carried out by trained personnel.

Science goes beyond the train

At the Jind station, Indian Railways has built an entire hydrogen chain: electrolysis, compression, storage, and dispensing. This facility can store nearly 3000 kg of hydrogen and is licensed to handle compressed gaseous hydrogen. Such infrastructure is critical because a hydrogen train cannot simply replace a diesel engine with a fuel cell; it requires a reliable supply of hydrogen, safe storage, compressors, dispensers, and qualified personnel.

This also explains the high cost of the technology. In 2023, the government estimated the cost of one train at approximately 80 crore rupees, and the infrastructure for one route at about 70 crore rupees. The Jind–Sonipat project, including the train and its facilities, was estimated at approximately 136 crore rupees. Consequently, the main question is not whether hydrogen can move the train. The chemistry is well understood. The test is whether green hydrogen can be produced cheaply enough, supplied safely enough, and utilized efficiently enough to justify its implementation on selected routes. For Indian Railways, the Jind–Sonipat service is not just a test of a new train, but an experiment in energy systems.