Limited battery power
In principal, electric planes sound like a great idea, but in reality there are a few hurdles to overcome before we’re all jetting across the world in battery-powered aircraft. The main problem is a lack of energy, as batteries cannot store enough fuel to get the jet off the ground. Making the aircraft lighter and increasing the efficiency of its propulsion can only go some way to rectifying this.
Even so, in March 2017, Wright Electric announced it was seeking backers to help fulfil its aim for “every short flight to be electric within 20 years” by building a 150-seat passenger plane with a range of 300 miles. Wright Electric is currently taking advice from easyJet on how best to develop this technology which, if it gets off the ground, will compete with the airline’s 156-seater Airbus A320 aircraft. And the hope is to do so by 2037, although experts have disputed this, claiming that advances in fuel-powered planes by then will offset the benefits of battery and hybrid.
Limited battery life
Battery life is another limiting factor, so flights will have to be short. However, if battery technology keeps improving at its current rate, battery weight and volume will shrink to allow flight length to increase. Wright Electric’s current designs show a 25-ton battery, which would never get off the ground, so clearly, improvements are required. Using a battery, the aircraft’s cruising speed will also be low, and fuel reserves will be required, which makes the current design a no-go. But it’s a start, and if battery improvements don’t materialise then the plane could be redesigned as a hybrid with electric motors.
With the help of the University of Illinois, aviation start-up Zunum has a different idea, developing a plane with its own power generator. When the battery runs low, a turbine in the plane would start running to recharge it, cutting fuel costs by 40-80%. The hope is to have a short-haul version in flight within 10 years or so, with a projected range of 175 miles, a number that will increase as battery technology improves.
Meanwhile, NASA is working on five separate research projects to create more efficient planes. One idea is to use Lithium-Air batteries, which create a current through oxidation of lithium and reduction of oxygen. Another plan is to replace the battery with a fuel cell, or even use a highly efficient cell that would produce electricity through the combination of oxygen from the air and hydrogen from jet fuel. While the latter method does still involve fossil fuels, it is cleaner and more energy efficient way to use them. The fourth proposal involves using a 3D printer to build the engine or to improve manufacturing techniques to make smaller, lighter and more power-dense motors.
Of course, if losing bulk is an issue, why not lose some of the plane itself? One weight reduction possibility is the tail fin, which could be replaced with less bulky wing stabilisers. The final of the five NASA projects is to track planes by satellite rather than radio, thereby reducing the size of the antennae required.
In comparison to the electric car
Despite these promising projects, there are a number of hurdles to jump before the electric plane becomes a viable option. Can all these issues be overcome? Well, let’s look back at the electric car. When they first appeared in the mid-19th century, electric cars had the same problem as planes: with high costs, low speeds and short battery lives they just didn’t go very far. Fast forward to the beginning of the 21st century and hybrid electric vehicles appeared, increasing the car’s range, although this came at a price. Tesla then revolutionised the market with their lithium-ion battery cells and now, in July 2017, there are 105,000 electric cars on the road in Britain. Tesla also runs a huge solar-powered battery plant in California, charging up batteries ready to power the electric cars of the future, as well as homes and businesses. If cars can do it, why can’t planes?
Current fuel-efficient aircraft
There are already some planes out there that are more fuel-efficient than others. Examples include the A320 NEO, which entered service in 2014 and burns 15% less fuel than previous A320s. The model is used by Virgin America, AirAsia, IndiGo, Lufthansa, Norwegian and American Airlines, among others. Meanwhile, the Airbus A3250 XWB, used by Emirates, Qatar Airways, Singapore Airlines and Cathay Pacific is made of lightweight materials, saving on weight and increasing efficiency. Within this, the A350-1000 burns 25% less fuel than its B777 equivalent. But one of the most efficient of all is the Airbus A380. Used by six carriers – Singapore Airlines, Qantas, Emirates, Lufthansa, Air France, Korean Air and China Southern – the A380 burns 20% less fuel thanks to more efficient engines and use of lightweight materials.
Perhaps the future of commercial aircraft is green after all.