Hertfordshire’s new trains have generated enough electricity through their brakes to power the equivalent of all the households of Welwyn Hatfield for a month, potentially saving more than 4,000 tonnes of carbon dioxide emissions.

For Great Northern passengers, travelling between London Moorgate and Stevenage, Hertford North and Welwyn Garden City, satisfaction was shown to have risen 22 percent as a result of the 25 new Class 717 trains.

The new trains, like the Class 700 trains used by Thameslink, are 20 per cent lighter than the previous generation. This causes much less wear and tear to the tracks and, combined with the trains’ regenerative braking system,  makes them 33 per cent more energy efficient than the old trains and have generated 17 million kWh.

Great Northern managing director Tom Moran said: “Our new trains have transformed our passengers’ journeys by replacing their cramped, outdated 42-year-old trains, with fully-accessible, spacious, modern air-conditioned units with the latest in passenger information, on-board Wi-Fi and power points at every pair of seats.

“Hidden away, underneath the carriages, electric motors help the trains brake, feeding the energy back into the network for use by other trains. That technology has already generated 17 million kWh – enough to power the homes of Welwyn Hatfield borough for more than a month, potentially saving more than 4,000 tonnes of carbon dioxide emissions.

“With all our managed stations now using energy generated from a clean, renewable source, passengers can travel safe in the knowledge they are doing their bit for the planet.”

The new Class 717 Moorgate fleet completed a £2bn fleet modernisation programme by parent company Govia Thameslink Railway, which also brought in 115 new Thameslink trains and new Class 387 carriages for the Gatwick Express and Great Northern, all with regenerative braking.

All these new trains, combined with the regenerative braking of other Southern Class 377s, mean that GTR’s fleet has generated more than 183 million kWh in the past 12 months, potentially saving more than 43,000 tonnes of carbon dioxide emissions.

GTR now only has diesel trains on just two routes, which are running outside Hertfordshire.