7th December 2017

Having become commonplace among cars, hybrid, electric and other powertrains are now being explored for planes

This year has seen conventional non-plugin hybrid car sales leap by almost 50% in the UK1, with a smidgen short of 58,000 of them registered by the end of October 2017. Whereas fully electric cars don’t provide the mileage ranges and fast refuelling capabilities that many drivers require, hybrid cars combining a petrol or diesel engine with a battery and electric motor have wide-ranging benefits, from lower CO2 emissions and relatively decent fuel economy credentials to hushed operation, making life more pleasant for cyclists, pedestrians and people enjoying a coffee sat outside a café.

Focussing the gaze upwards to the skies, air travel has long been cited as a major contributor to global warming, pollution and other environmental concerns, with just a return flight between New York and Los Angeles reported to generate around a fifth of a typical car’s annual greenhouse gases2. Per person, it has admittedly been calculated that an air passenger flying from Heathrow to Edinburgh would be apportioned 79kg of CO2 emissions, while someone driving a diesel Mondeo would be responsible for emitting 98kg of CO2, but it was reckoned that one plane would equate to over 330 cars3. Vapour trails can be seen in the skies above many global locations, while planes consume a huge amount of aviation fuel, and noise is a major gripe for people and businesses situated near airports and along flightpaths.

While air travel is used by fewer people than cars, vans, lorries, buses and trains, many aircraft manufacturers forecast that orders for large planes are set to double over coming years4. It’s encouraging to see rival aviation firms joining forces with the appreciation that cleaning up the planet is more important than other traditional business objectives. Airbus and Rolls-Royce along with Siemens have announced a collaboration to develop hybrid electric plane technology into a viable wider application as swiftly as possible.

Just like electric cars and vans are held back by their limited ranges and weighty batteries, the aviation industry knows that electric planes are a long way off a reality, but the trio’s E-Fan X programme will hopefully see a Bae 146 aircraft take to the skies in just a couple of years, one of its usual four jet engines replaced by an electric one. Hybrid-electric technology in ‘series’ formation is seen as the saviour of air travel in the near future and the E-Fan X plane will feature a Rolls-Royce electricity generator at the rear, while Siemens will fit the 2MW electric motor, cooling fan and electronic systems, and Airbus will look after the energy storage, power distribution and user interface angles5.

Hybrid cars have long been synonymous with intelligent energy usage and techniques, such as topping up their batteries via regenerative braking – and hybrid planes are set to act similarly. Their turbines will run on jet fuel and will supply power to the electric engines, with surplus power stored in battery banks for use in take-off and landing, which account for a good chunk of a flight’s overall fuel, emissions and also noise pollution. Component amalgamation will also ensure that hybrid planes are lighter than conventional aircraft, contributing towards improved fuel economy and a reduction in harmful gases outputted.

Boeing, another of the world’s leading aircraft manufacturers, is also pouring resources into developing hybrid-electric plane technology, its Horizon X arm having invested along with JetBlue Airways/Technology Ventures in a startup from Seattle called Zunum Aero6. They’re being realistic, freely acknowledging that they probably won’t be the first to bring a fully ready and certified plane to market, but their aim is clear – to fill a gap in the regional air travel sphere by making private jets and commercial jetliners cheaper to use, obviously in a very relative sense.

Just like the Airbus effort we opened this article with, Zunum’s hybrid-electric plane will initially be modest in size, seating just 12 passengers plus crew, power coming from a brace of electric motors fed by batteries, with a supplementary jet-fuel engine and electrical generator topping power up when required. Think of it in a similar way to BMW’s i3 Range Extender. In the States, where the plane will initially be launched, less time-consuming security checks are required for travel on small aircraft, and Zunum reckons that by combining this advantage with its efficient technology, it’ll be able to help regional flight operators to finally become profitable. Within 12 years, Zunum believes it will have been able to develop and certify a 50-seater plane with a range of 1,000 miles and significantly reduced emissions and noise pollution credentials.

Once again reflecting what is happening in the world of cars, vans and trucks, aviation firms have also been experimenting with hydrogen fuel cell technology to make their planes more environmentally friendly, Boeing conducting a test in 2008 involving a light aircraft. In early 2016, EasyJett7 unveiled plans to trial a larger hybrid plane featuring a photovoltaic blanket, water tank, hydrogen fuel cell store, regenerative braking and a green taxiing system. After much digging we’ve not unearthed the trial’s results, but EasyJet is now passionately championing fully electric power and as a start is using Heathrow’s revolutionary new electric, towbar-less, remote-controlled tugs to manoeuvre its planes8. Within twenty years, the budget operator wants to see its short-haul routes flown by all-electric aircraft and is developing a prototype in conjunction with Wright Electric, the plane reportedly having a range of 335 miles, allowing it to take London to Paris in its stride as an example9. To make its creations as aerodynamic as possible, Wright places the electric motors inside the planes’ wings rather than underneath them.

NASA10, meanwhile, is developing a series of X-planes that will boast rather different efficiency-boosting technology equipped with ‘turbofan jets and a boundary layer ingesting engine’, which essentially means that air flowing along the sides of the plane is collected by huge fans and then converted into thrust. A plane’s main engine is responsible for a large percentage of the power required for take-off and cruising, so NASA has fitted its Single-aisle Turboelectric AiRCraft with two separate under-wing engines that will power the trio of fans. The space exploration firm is also developing a Quiet Supersonic Technology (QuesSST) aircraft, seeking to produce green, fast and quiet planes for hundreds of passengers.

As a company rooted in automotive solutions, it’s been fascinating to see how the aviation industry has been tirelessly pioneering wide-ranging applications using similar principles to those now seen in cars, vans and even trucks, helping to make travelling cleaner, quieter and faster for all.


1. https://www.express.co.uk/life-style/cars/865937/electric-car-uk-hybrid-cars-sales-petrol-diesel-ban
2. https://www.nytimes.com/2017/07/27/climate/airplane-pollution-global-warming.html
3. http://www.sciencefocus.com/qa/how-many-cars-equal-co2-emissions-one-plane
4. http://australianaviation.com.au/2017/12/tourism-boom-and-rise-of-the-middle-class-to-spur-growth-in-australia-nz-and-south-pacific-airbus/
5. http://www.bbc.co.uk/news/business-42152484
6. https://www.reuters.com/article/us-aerospace-hybrid/boeing-backed-hybrid-electric-commuter-plane-to-hit-market-in-2022-idUSKBN1CA16A
7. https://www.theguardian.com/travel/2016/feb/02/easyjet-plans-cut-carbon-emissions-hydrogen-fuel-cell-trial
8. https://www.engadget.com/2017/10/03/easyjet-innovation-day-tech-electric-planes/
9. http://www.bbc.co.uk/news/business-41404039
10. http://www.greenmatters.com/news/2017/11/10/1lEgzE/nasa-aviation-renaissance-next-gen-aircraft