Sheffield waste management company Veolia opened its doors to the public to show what happens to the city’s waste.
Over 100 visitors were given a tour of the energy recovery facility, on Bernard Road, which opens to the public once a year.
The plant burns household waste to generate heat and hot water for 150 buildings in the city and electricity to the National Grid.
Plant manager Antony Smith said: “The tickets went in a flash. We’re being asked to repeat the experience.”
Jack Weaver, aged 11, who visited the plant with his parents, said: “It was great. I operated the crane in the control room, it was just like being in charge of a spaceship.”