Rolls-Royce has started building what is claimed to be the world’s largest aerospace engine that promises to make flights greener.

The ‘green’ engine is being built at the British company’s DemoWorks facility in Derby and is designed to offer a 25% fuel efficiency improvement compared with its first-generation engine.

The firm said the first test run of the engine will be conducted on 100% sustainable aviation fuel.

The project has been supported by the Aerospace Technology Institute, Innovate UK, the German federal aviation research programme LuFo and Europe’s Clean Sky Joint Undertaking.

UK Business Secretary Kwasi Kwarteng said: “The UltraFan project is a perfect example of how we are working with industry to deliver green, sustainable flight for decades to come.

“Backed with significant government support, this project represents the scale of ambition for Britain’s crucial aerospace sector.”

Chris Cholerton, President of Civil Aerospace, Rolls-Royce, said: “It is arriving at a time when the world is seeking ever more sustainable ways to travel in a post-Covid- 19 world and it makes me and all our team very proud to know we are part of the solution.”