The rows of brick sheds that are hidden down country lanes in Bedfordshire feel far removed from the brightly lit boardroom presentations on sustainable aviation. It was, however, the backdrop to an extraordinary scene in the quest for greener flying.Bobby Sethi, an associate professor of gas turbine combustion at Cranfield University, said that anyone who saw them would have been puzzled why they were laughing and staring at a piece of pipe. We were almost certain to be the only ones in the world who could then burn anything without producing CO 2.Sethi and his team celebrated a breakthrough in the difficult groundwork that was required to test whether hydrogen could be used as a fuel for global air travel.He says that we were able demonstrate safe ignition and safe combustion at high pressure and temperature, producing no carbon emissions. He adds that even if the passer-by layperson had only seen a pipe or some steam, it was still impressive.Sethi was a ghostbuster character based on Harold Ramis's character from Ghostbusters. He had been working in an obscure, almost-derided field for a long time before society decided it was indeed spooked. In this instance, jet fumes were frying the planet. Who are you going to call? Cranfields Centre for Propulsion Engineering.Cranfield University, an old piece of fuselage taken from an easyJet plane. Photograph by David Levene/The GuardianSethi recalls the skeptical attitude of five years ago when he was trying to get funding for Enable H2's hydrogen research project. They are now waiting to join our advisory board.The aviation industry is currently focusing on three main areas of work in order to create an environmentally-friendly future. The first is to develop greener fuels for large aircraft in service. The second option is electric flight. This seems feasible for small aircraft and short-haul flights. A third option is hydrogen.Cranfield has pioneered two projects that use hydrogen as fuel cells to propel planes and power electric motors. ZeroAvia flew six seats from Cranfield last September and plans to expand the technology to commercial short-haul flights. Project Fresson is another project that plans to use fuel cells for a green, short hop passenger service around Orkney islands. This will be in 2023.However, the ambitions to direct combustion of hydrogen are much larger. It is possible that a completely new plane and propulsion system will replace the current paraffin-fuelled passenger aircraft. This is where Sethis research steps in.The sheds do not look like a plane yet. Sethi says the rig is unique and was built to demonstrate that hydrogen can be safe, clean and efficient for aviation. It also produces data to show the optimal temperature and pressure to minimize other harmful emissions like nitrogen oxides (NOx), a group of highly poisonous gases.The purpose-built airport terminal at Cranfields, with a departure gate and lounge, was completed in 2007. Photograph by David Levene/The GuardianThe largest component of the system is the pebble-bed heater pressure container. This delivers super-hot, high-pressure air into a combustion chamber where hydrogen is mixed in. To observe the flame's shape and to provide additional data, there are several crates of lasers that can be found outside.He admits that the combination of lasers with combustible hydrocarbon sounds dangerous and could cause serious health and safety problems. A nearby control room has a large red stop button to prevent nitrogen from flooding the system. He believes that the experiments will show that hydrogen at altitude is not more risky or difficult to ignite than paraffin.Although hydrogen is technically feasible, there are still many areas of research and development that need to be done. Hydrogen's main problem is its cost.He believes that this will change as fossil fuels become politically and environmentally unsustainable and taxes, subsidies, and demand change. He believes that hydrogen will be a part aviation sometime between 2040-2050 depending on political pressure and subsidies.He adds that hydrogen has come back to the forefront because of pressure from green lobbyists like Extinction Rebellion.Cranfield has seen a significant increase in interest in sustainable aviation. This has resulted in a resurgence in research. Tim Mackley, the head of the university's Aerospace Integration Research Centre says, "We were always interested efficiency, but in the past two or three years, there has been a large push towards saying that what manufacturers were actually planning was not enough."Subscribe to Business Today's daily email or follow Guardian Business @BusinessDesk on Twitter.Safs (sustainable aviation fuels) could help reduce carbon emissions. Last month, the government announced early funding for eight UK-based projects. These projects will build plants that convert household waste, carbon dioxide from the atmosphere, and sewage into commercial jet fuel.Mackley states that Safs are only an interim measure. They can be sustainable in terms of production, but they still produce CO2. Mackley says that Safs are only an intermediate measure. This is due to the huge carbon impact of replacing entire fleets of aircraft worldwide with newer types.Short-haul hops could be made with something as strange as the craft found in Mackleys' Cranfield. This experimental eVOTL, an electric vertical takeoff-and-landing aircraft, is a joint development project with Rolls-Royce. While partial footage of this plane generated some excitement when it was posted online last year, the complete picture shows a problem: It moves by being attached to a large truck.Tim Mackley and I look at an eVTOL plane at Cranfield University. Photograph by David Levene/The GuardianMackley says that this model was not intended to fly. The model was designed to show how the rotors react to the transition between vertical liftoff or forward thrust. Because the model is too large to be placed in a wind tunnel it is attached to an ex-German firetruck and driven down Cranfields runway. It was the only thing that could accelerate the aircraft to 80 mph, and also the power to propel it.Cranfield is just one of the many people involved in eVTOLS. They work often in isolation and produce very unique designs. Mackley sometimes admits to the audience during the big reveal: Yes, I do believe that.He says, "To make electric the best it can be we must be creative about how that looks."He says that planes will change, whether they are electric or hydrogen, and may fly slower than ever before. Designers must consider how passengers will use their planes, as well as the environment. He warns that if you don't create the type of concept airlines love, it will not succeed.
