Why in news?

PM Modi will flag off India's first hydrogen-powered train in Jind, Haryana, on July 17, 2026.

With this, India joins an elite group of countries, including Japan, South Korea, the US, and Canada, that operate hydrogen trains ("H-trains"), marking a major milestone in green transportation technology.

What’s in Today’s Article?

• Key Features of the Train
• Global Context: Hydrogen Trains Elsewhere
• How Do Hydrogen Trains Work?
• The Storage Challenge
• Conclusion

Key Features of the Train

• India's hydrogen train is among the world's longest and most powerful hydrogen trainsets, with the following specifications:
  • Configuration: Eight passenger cars and two driving power cars (10 coaches total)
  • Power: 2400 kilowatts (3200 hp)
  • Capacity: 682 seats, with a total passenger capacity of 2,600
  • Route: 89-km Jind-Sonipat section via 12 stations, with a 2-hour travel time
  • Speed: Operational speed of 75 km/h, maximum speed of 120 km/h
  • Operations: Two round trips daily, covering 356 km and consuming about 300 kg of hydrogen
  • Emissions: Zero CO2 emissions; the only by-product is harmless water vapour

Global Context: Hydrogen Trains Elsewhere

• French rolling stock giant Alstom first presented hydrogen train technology at a 2016 exhibition in Berlin.
• Its Coradia iLint train-set was launched in Germany in 2018, becoming the world's first hydrogen-powered passenger train.
• Japan, China, and the US subsequently launched their own hydrogen trains.
• However, the technology remains in an evolving stage for mass transportation of passengers and freight, which is why few countries operate such trains, and mostly for short-haul routes.

How Do Hydrogen Trains Work?

• Unlike conventional electric locomotives that draw alternating current from overhead wires, hydrogen trains generate their own electricity by combining hydrogen with oxygen.
• In India's hydrogen train, each of the two power cars houses four integrated power packs, comprising hydrogen fuel cells and lithium ferro phosphate batteries.
• The fuel cell draws hydrogen stored on board (440 kg, at high pressure) and combines it with oxygen from the outside air to generate electrical energy.
• Power distribution
  • Each power pack generates 300 kW (115 kW from the fuel cell, 185 kW from the battery).
  • Four power packs together provide 1200 kW per power car, and with two power cars, total power reaches 2400 kW, comparable to conventional electrical or diesel-electric multiple unit trains on similar routes.
• Working mechanism
  • The fuel cell delivers constant power output. At start-up, when power demand is low, surplus fuel cell electricity charges the battery.
  • As speed and power demand increase, the battery supplements the fuel cell.
  • Near the station, as demand drops again, the battery recharges using surplus fuel cell energy, ending the journey nearly 80% charged.
  • The train was essentially created by replacing diesel engines in old diesel-electric multiple unit (DEMU) rakes with this hydrogen-electric propulsion system.
  • The core fuel cell technology has been imported from Canadian company Ballard.

The Storage Challenge

• Storing and transporting hydrogen safely is the biggest technical hurdle.
• While normal atmospheric pressure is one "bar," hydrogen must be stored at 200-500 bar, making it highly flammable and difficult to handle.
• Additionally, hydrogen production levels remain low globally, and transportation is logistically challenging.
• To address this, Indian Railways has set up a 3,000-kg-capacity fuelling facility at Jind, along with a chiller plant that cools hydrogen to minus 15°C during dispensing, converting it into a liquid state for safer and easier handling.

Conclusion

India's first hydrogen train marks a significant stride toward clean, zero-emission rail transport, placing the country among a handful of global pioneers.

However, challenges around hydrogen storage, production, and cost mean its long-term expansion will depend heavily on the pilot project's real-world performance on the Jind-Sonipat route.

Why in news?

The Video Assistant Referee (VAR) system came under intense scrutiny during the FIFA World Cup clash between Egypt and Argentina in Atlanta. A well-crafted Egyptian goal was disallowed after VAR intervention flagged a foul in the build-up, sparking outrage from the Egyptian camp.

Egypt, which surrendered a two-goal lead to lose 2-3, argued that certain fouls by Argentina were ignored in the same passage of play.

The episode has reignited debate over VAR's consistency and transparency.

What’s in Today’s Article?

• What is VAR and How Does It Work?
• When Can VAR Intervene?
• The Egypt-Argentina Controversy
• Key Criticisms of VAR

What is VAR and How Does It Work?

• VAR refers to both the video review system and the chief referee who monitors play, typically from a central hub.
• The system was proposed in the early 2010s and approved by the International Football Association Board (IFAB) in 2016, with the primary objective of avoiding "clear and obvious errors" during key match incidents.
• The setup includes multiple high-quality cameras positioned around the venue and a pitch-side monitor near the dugouts.
• The VAR official recommends that the on-field referee review certain incidents, but the final call rests with the on-field referee, who can accept or reject the recommendation even after review.

When Can VAR Intervene?

• VAR is primarily used to review four categories of decisions: goal or no goal, penalty or no penalty, direct red cards (including reversals), and cases of mistaken identity.
• At this World Cup, its third consecutive edition since introduction in 2018, VAR has taken on additional responsibilities, including reviewing wrongly awarded corner kicks and correcting incorrectly issued second yellow cards.

The Egypt-Argentina Controversy

• Egyptian player Mostafa Zico scored following an impressive attacking move, but the goal was disallowed after VAR official Jerome Brisard flagged a possible foul by Egypt's Marwan Attia on Argentina's Lisandro Martinez elsewhere on the pitch.
• On-field referee Francois Letexier reviewed the footage and ruled that Attia had unfairly won the ball in the build-up, disallowing the goal.
• Egypt contested this decision on two grounds:
  • that the foul occurred away from where the goal-scoring move began, and
  • that no similar review was granted for alleged fouls on Egyptian players inside Argentina's box just before Argentina's winning goal.
• FIFA's chief refereeing officer clarified that there is no defined limit on distance or time between a foul and a goal for VAR to intervene in the build-up.
• FIFA's Response
  • Following the backlash, FIFA introduced a significant operational change: two in-house VAR officials will now be appointed for every match from the quarterfinals through the final.
  • This is aimed at improving oversight and consistency in decision-making.

Key Criticisms of VAR

• Inconsistency: Similar incidents are often judged differently by different referees, creating confusion over what constitutes a penalty or red card.
• Over-officiating: Critics argue VAR is making football "soft" by flagging fouls barely visible to on-field officials, as seen in Germany's disallowed goal against Paraguay in the round-of-32.
• Lack of transparency: Fans, players, and coaching staff are frequently left uninformed about the reasoning behind VAR's recommendations to the on-field referee.

Conclusion

The Egypt-Argentina episode has exposed persistent flaws in VAR's application, particularly around consistency and communication. While FIFA's move to add a second VAR official signals responsiveness, the deeper challenge remains balancing technological precision with football's fast-paced, human character.

About Molluscs:

• Molluscs are extremely diverse invertebrate animals.
• Habitat: They are found in nearly all freshwater and marine environments, and some are found also on land. 
• They come in all shapes and sizes, and some of them grow external shells to protect their soft bodies.
• These are a quarter of all living marine species and also have importance as food sources.
• The molluscs include many familiar animals, including clams, snails, slugs, and squid, as well as some less familiar animals, like tusk shells and chitons.
• Major groups within the Mollusca
• Polyplacophora: It consists of chitons, snail-like molluscs with eight-part overlapping scale shells
• Gastropoda: These are true snails and slugs. They represent the most diverse class within phylum Mollusca with 60,000 to 80,000 extant species in marine, freshwater, and terrestrial habitats.
• Bivalvia: These are molluscs with hinged two-part shells. Examples include clams, oysters, mussels, and scallops.
• Cephalopoda: These are molluscs with large heads, large eyes, and grasping tentacles
• Examples include octopus, squid, cuttlefish, and nautiloids.