As pressure grows on airlines to reduce their climate change impact, and “flight shame” grows among people concerned about their own impact, ever more research is being put into alternative, “cleaner” sources of fuel. Katie Prescott travels to Oslo to see new projects to bring more so-called biofuels into the system. Air BP’s commercial development manager, Tom Parsons, explains the difficulties in implementing and costing biofuels, while Dr Andrew Welfle at the University of Manchester describes the potential sources and applications of biofuels. (Picture: At a plant near Chiang Mai, Thailand, cooking oil and palm oil are processed to produce biodiesel. Picture credit: John van Hasselt/Corbis via Getty Images)