It’s a predictable fact that future aircraft won’t be as polluting as today’s aircraft is, but where technology will take us is yet to be decided. For that matter, Boeing is predicting that the future fuel for planes will be liquefied natural gas (LNG), and their idea is being supported by NASA, whose specialists think that by 2045 airlines will be using this technology.
They chose LNG because it outputs less carbon dioxide and other greenhouse gases and its overall price is lower. They called the concept SUGAR Freeze (Subsonic Ultra Green Aircraft Research), and you may have already guessed where Freeze comes from (cryogenically stored LNG).
Boeing designed the propulsion system to burn LNG in unducted-fan hybrid engines. These, in turn, will be connected to a fuel cell that would produce electricity for a rear-mounted thruster that would reduce drag by re-energizing the wake of the aircraft. This would all result in a 64% efficiency improvement over a 737-800.
For the moment, SUGAR Freeze is being designed for commuter aircraft, because of the relatively low performance needs, but the need to green up aviation is perpetual, so it will eventually move to long distance travels. If fuel cells are already included in the menu, it’s highly possible that the plan will ultimately change, so that they’ll end up with an electric airplane powered by methane fuel cells – a very plausible solution, in my opinion.
Anyway, any idea regarding any modification to aircraft has to be thoroughly tested, and that’s why this technology can’t be adopted sooner than 20 years from now. At the current rhythm of technological development, it’s a sure fact that things will change.