The effect of air travel on global warming has remained a major concern, which has forced the aviation industry to search for alternative technologies that can help reduce emissions and thereby, improve the environmental impact of air travel. Presently, air transportation accounts for about 4% of the global greenhouse gas emissions. This the reason why the aviation sector is giving a serious thought to the hybrid electric aircraft.
A hybrid aircraft is basically an aircraft that has gas turbine engines and electrical propulsors. The main advantage of the hybrid-electric propulsion system is that it has the potential to lower fuel consumption and emission levels while also reducing vibrations and the take-off noise.
The hybrid-electric propulsion system contains both electric motors and internal combustion engine to get the best of both worlds. A hybrid aircraft is mainly powered by electricity, while the turbine generators are used during take-off and climb when the aircraft requires a huge amount of power.
Several important players in the aviation sectors have already taken initiatives to develop and operate electric-hybrid aircraft. For example, Boeing and JetBlue are backing Zunum Aero, which has been working on a family of hybrid electric regional aircraft since 2013. The company began the development of a 6 to 12-seat aircraft in 2017, which is expected to fly in 2020. Airbus has also teamed up with Siemens and Rolls Royce plc. to develop E-Fan X hybrid-electric airliner demonstrator, which too aims to fly in 2020.
However, the main limitation of such aircraft is the amount of power that needs to be generated on-board, which necessitates a significant increase in on-board power generation capability. This in turn, will require developments not only in the design of aero-electrical power systems but also in appropriate technologies. So, the hybrid systems will have to improve rapidly in order to be adopted in a large scale. As of now, the potential of such aircraft is limited for general aviation.
But since the airline industry aims to cut down its carbon dioxide emissions to half by 2050 from 2005 levels, we can expect the introduction of some really disruptive technologies and innovative aircraft in the coming decade.
The market for hybrid aircraft was valued at around 540 million USD in 2016 and is expected to reach around 1,200 million USD by 2025, fuelled by factors like environmental concerns and also due to the fact that these aircraft require less fuel than the conventional aircraft.