Several rail bodies due to take part in the “high-level” event to showcase the Hydroflex train have privately expressed surprise the journey from Central Station round the Cathcart Circle will not be fuelled by hydrogen.
It means the dignitaries will travel on a 30-year-old train that has been converted to run on the gas but which will be powered by traditional overhead electric wires instead.
Train leasing firm Porterbrook insisted there were no problems with its UK-first train and it could have operated the trips using hydrogen.
Chief executive Mary Grant said the company wanted to show off the interior of the train’s “ground-breaking” hydrogen tanks – so they had to be empty – and it had “chosen not to” run it on hydrogen.
She said: "It‘s doing a disservice to the innovation and design to not show it.
"Your jaw will drop – I promise you.”
But the decision was news to three of the industry bodies involved in Tuesday’s event who said they had expected the train to run on hydrogen.
One said: “We thought it was a hydrogen train.”
Another said: “We had assumed hydrogen, but that hasn’t been specified.”
A third said: “The obvious answer to this would be yes.”
Meantime, BMAC, which makes components for the train, announced last week: “This cross-industry collaboration will see the ground-breaking Hydroflex make its first passenger journeys at COP26 to showcase the possibility of leading British green technology on the world stage.”
Organisers described Tuesday’s event as a “high-level sustainable transport gathering” with “key public transport leaders...representing both the public and private sector from around the globe”.
It will be jointly hosted by International Association of Public Transport secretary general Mohamed Mezghani and International Union of Railways director general François Davenne.
Others invited to take part include French railways SNCF chief executive Jean-Pierre Farandou, train manufacturer Alstom’s vice-president for sustainability Cecile Texier, Elisabetta Tromellini, her opposite number at the FNM Group, one of Italy’s biggest rail firms, and Valerie Davidson, acting chief executive of Strathclyde Partnership for Transport, which runs the Glasgow Subway.
The following day, the winners of a schools’ competition to encourage more rail travel are due to travel on the train with MG Leonard and Sam Sedgman, authors of the Adventures on Trains books.
Network Rail, which is co-hosting that event with Porterbrook and publishers Macmillan, said: “Primary schoolchildren from Glasgow will join the authors, along with engineers from Network Rail and Porterbrook, for a fun-packed literary journey where they can learn about the secrets of storytelling and how technology is powering rail’s green revolution in Britain.”
A Porterbrook spokesperson said: “During COP26, invited guests will have the unique opportunity to enter the HydroChamber and explore the ground-breaking technology that will allow this train to use green hydrogen in self-powered mode.
“This will be the last opportunity to see inside the HydroChamber as immediately after the conference, the interior will have special safety containment walls fitted, prior to being fuelled and commissioned for hydrogen operation.”
Porterbrook said Hydroflex was the world’s first hydrogen train that could also run using overhead electric wires or batteries.