Ashley Dove-ay writes:  The aircraft industry is expecting a seven-fold increase in air traffic by 2050, and a four-fold increase in greenhouse gas emissions unless fundamental changes are made. But just how “fundamental” will those changes need to be and what will be their effect on the aircraft we use?

The crucial next step towards ensuring the aircraft industry becomes greener is the full electrification of commercial aircraft. That’s zero CO2 and NOx emissions, with energy sourced from power stations that are themselves sustainably fuelled. The main technological barrier that must be overcome is the energy density of batteries, a measure of how much power can be generated from a battery of a certain weight.

Tesla CEO Elon Musk says that once batteries are capable of producing 400 Watt-hours per kilogram, with a ratio of power cell to overall mass of between 0.7-0.8, an electrical transcontinental aircraft becomes “compelling”.

Another aspect is an exponential fall in the cost of solar panels, which have already become the cheapest form of power in most US states. The expected 70% fall in cost of lithium-ion batteries by 2025, and the rapid rise seen in the cost of kerosene-based jet fuel means that there will be a large and growing disparity in the costs of running aircraft that will greatly favour electrification.

Once electric aircraft are established, the next step will be to integrate a gimballed propulsion system, one that can provide thrust in any direction. This will remove the need for the elevators, rudders, and tailplane control surfaces that current designs require, but which add significant mass and drag.