With the Solar Impulse 2 journey across the world coming to an end, it seems the new buzz in renewables revolves around aircraft. Innovative new electric aircraft are starting to find their way on runways and promise cleaner, quieter and safer flights than jets, with a fraction of their carbon footprint.
Commercial aviation currently accounts for 2% of all man-made CO2 emissions, and is expected to rise to 22% by 2050 – however electric aircraft could slow these figures, or even roll them back.
Nasa recently announced that it would be building a research aircraft called ‘Maxwell’ that would use electric motors to drive 14 propellers. The aircraft should be able to seat four and fly at speeds of up to 175mph whilst using a fifth of the energy of a normal private plane.
“Eventually, Nasa would love to replace airplanes like the Boeing 737 or Airbus A320 that represent a large fraction of civil aviation,” says Jack Langelaan, a professor of aerospace engineering at Penn State University. “A huge proportion of today’s emissions and fuel burn comes from these kind of planes.”
“There are a lot of things we need to get sorted out to make this work,” says Langelaan. “Collision avoidance and traffic management are important. It’s a big sky but once a lot of these little airplanes start flying around, the sky will start looking an awful lot smaller.”
There are other technical challenges for electric aircraft to overcome too, not least the state of battery technology. Range anxiety takes on a whole new meaning when you’re worried about reaching the next runway. “Lithium ion batteries are not at the point where you have the power density to build an aircraft with long range,” says Schaefer. “You’re limited to about an hour’s flight.”
Aerospace company Aurora Flight Sciences gets around this problem by using a hybrid system, where three one-megawatt generators, powered by jet fuel, drive the Lightning Strike’s electric motors. Lightning Strike is being developed as an electric drone for the US Military.
“A greener solution is to generate power as you need it, using photovoltaic cells. Solar Impulse 2 recently became the first aircraft powered solely by renewable energy to cross the Atlantic, as part of a round-the-world tour. But the Solar Impulse can carry only one person, has a top speed lower than most cars and costs millions of dollars to develop.
“As solar cell efficiencies get better; you’re going to see solar-powered airplanes with more traditional dimensions.”
The good news is that all the technologies behind electric planes, from batteries to solar cells to the motors themselves, are getting better, lighter and cheaper all the time. The large jet makers are paying attention. Boeing and Airbus have experimented with electric aircraft, and even Tesla boss Elon Musk has hinted that he is considering building an all-electric plane.
Just like today’s Tesla, Prius and Leaf cars, hybrid and electric planes will have much lower running costs than traditional propeller or jet aircraft. The maker of the solar-powered Sun Flyer electric plane says it uses just $1 of electricity for each hour of flying time, compared to $40/hour for a fossil-fuel powered light aircraft.” The Guardian.
The sky is set to look a lot cleaner with the innovative use of renewable energies to develop electric aviation. Solar PV does not only help to save the planet; it now helps us to travel around it.