Rolls-Royce is pressing ahead with development of hybrid-electric technology despite scrapping its project with Airbus in April, as aviation companies race to tackle unsolved challenges that will help meet aggressive carbon-reduction targets over the coming decades. "The E-Fan X testing facility remains open and will continue because that's something we have learned from and it is fundamentally continuing," Rachael Everard, head of sustainability at Rolls-Royce, told <em>The National</em>. "We are looking at how some of our hybrid-electric demonstration platforms could be adapted to run on hydrogen," she said. Last month, Airbus appeared to bound ahead, <a href="https://www.thenationalnews.com/business/aviation/airbus-unveils-three-designs-for-zero-emission-aircraft-1.1081115">revealing three designs it is considering to build a hydrogen-powered aircraft</a> as it seeks to bring the world's first emissions-free passenger plane into service by 2035. Rolls-Royce, meanwhile, with its research partnership with the world's largest plane maker on hold, is stepping up its own de-carbonisation strategy. Hydrogen will play a key role, Ms Everard said, but the universe's lightest element still presents many challenges for the aviation industry. Storage solutions need to advance to carry enough liquid hydrogen to power planes for long journeys and infrastructure for transporting and refuelling on runways needs to be devised. Plane interiors will also need to be reconfigured to run commercial planes on hydrogen. Still, a review this year by the EU Commission found that hydrogen could be used by 2035 to power a commercial passenger aircraft on a flight of up to 3,000 kilometres. By 2040, a medium-range flight of up to 7,000km should also be possible, leaving the issue of long-range flights still to be solved. "That means on European soil, you could connect all the big cities in Europe using hydrogen-powered planes," said Dr Bart Biebuyck, executive director of the Fuel Cells and Hydrogen Joint Undertaking, which took part in the report. "By 2050, the ambitious scenario is that 40 per cent of the [European aviation] fleet would be powered by hydrogen." With the aviation industry facing the worst economic shock in its history, leaders are advocating for a green recovery. In June, around the time when flight hours were at their lowest worldwide, Rolls-Royce committed to becoming a net zero- carbon-emissions company, in its operations and in what it produces, by 2050. "This cannot be achieved with the technologies existing today," Ms Everard said. "Therefore, we're focusing research work in different technology areas including electrification. Electric and hybrid-electric propulsion are seen today as among the most promising technologies for addressing these challenges," she said. Rolls Royce is also working to understand the challenges of hydrogen-fuelled propulsion systems and developing roadmaps to build the needed technology to overcome hurdles and get new engines to market. In 2019, Rolls-Royce invested $2.1 billion in gross R&D expenditure, with support from international governments, and it currently has 830 new patents approved for filing. It also has partnerships with 29 university technology centres and seven advanced research and manufacturing centres that develop intellectual property that can be applied in Rolls-Royce technology and across manufacturing, according to the company. Ms Everard is more optimistic than some in her industry. "Some small hydrogen-powered aircraft could potentially be available before the end of the decade," she said.