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Aviation has come a long way since the Wright Brothers first took to the skies early in the 20th Century. Gone are the flimsy glider assemblies that carried a single person: today’s aeroplanes are gargantuan structures that can transport hundreds of people from A to B at almost 600 miles an hour.
Effects of Modern Aviation
Modern aviation is, however, incredibly polluting, accounting for approximately 3% of the human global warming footprint. This is likely to grow as countries become more developed and people jet off for holidays or on business trips. It has been suggested that we need to think about how we fly, and the aviation industry is under enormous pressure to reduce carbon dioxide emissions post-2020 to help mitigate climate change.
The good news is that steps are already being taken: older planes reaching retirement are replaced with ones that are more fuel efficient; and flights are being scheduled to ensure fewer empty seats.
But what more can be done? Should aircraft be slimmed down or redesigned, or could air traffic operations become more streamlined? Other ideas under investigation include the use of biofuels over jet fuels, fuel cells, or solar-powered planes.
In 2015, Solar Impulse 2, a solar-powered single-seat aircraft with a wingspan wider than a Boeing 747, became the first solar aeroplane to complete an oceanic crossing, flying from Japan to Hawaii using nothing but solar power. This is the ultimate goal for solar-powered aircraft - achieving continuous flight.
It’s a simple concept: the wings are covered in solar cells – Solar Impulse 2 has 17,000 across its jumbo-jet sized wings – which harvest the sun’s energy. Some of this energy is used immediately to power the propulsion system and onboard instruments, the rest is harnessed in a rechargeable energy storage system – four lithium-polymer batteries in the case of Solar Impulse 2 – to power flight at night. This is enough to carry around two tonnes of weight – including a single passenger at a top speed of 43 miles per hour.
Furthermore, it releases no harmful exhaust gases, there is no contamination of the atmosphere and it is eco-friendly.
That may seem impressive – and perhaps it is for this early stage technology – but when you consider a Boeing 747-400 although heavier and more polluting, can transport 400 passengers at 570 miles per hour, not so much. There still needs to be some huge advances made before a solar-powered aircraft can be used commercially.
However, is the idea of using solar-powered aeroplanes a good one? Yes and no – perhaps for those who fly recreationally, the slow speed of the light-weight solar-powered aircraft isn’t a problem. However for those who need to get from one side of the world to the other, the traditional jet-fuelled plane is still the better option.
Advances in Aircraft Design
If not solar power, what? Redesigning current planes is an option being explored – the next generation of planes could have open rotor engines, and complete carbon fibre frames. NASA and Boeing are currently exploring the design of the wings suggesting longer, thinner wings supported by a truss could cut fuel use by up to 50%. Their current design performs incredibly well in wind tunnel experiments, but changing the whole design is a big risk – especially if it turns out to be wrong – so it’s unlikely to be seen in new aircraft just yet.
The use of low-carbon biofuels is another option, and it is hoped that it could replace up to 30% of jet-fuel by 2050. The fuel is likely to be made of cellulosic biomass – grasses and inedible parts of plants – or algae. While some planes have already flown on experimental fuels made from green sources, its not certain that the required quantities of such fuel would be available for its widespread use. Scaling up the process used to create the fuel is difficult, and biofuels are still expensive – approximately 3-4 times more than jet fuel, although this price may decrease as production increases.
Solar-powered aircrafts may not be the future of commercial aviation – redesigned planes powered by greener fuels are more likely to take the crown, but could it have a place in recreational flight – time will tell.
References and Further Reading