Will flying ever be sustainable?
Will flying ever be sustainable?
BETH BARKER: Making aviation green is a huge challenge. Flying is such a big part of our lives and we have to balance that with the fact that it contributes hugely to global warming. CAIT HEWITT: We've left it a long time. We've now got a very short window within which we need to get emissions from this sector down to nearly zero. We need to be throwing everything at this problem that we can think of. (CAN FLYING EVER BE SUSTAINABLE?) (CAIT HEWITT Policy Director Aviation Environment Federation) CAIT HEWITT: There are two big reasons why aviation presents a unique challenge in terms of climate change. The first is that more and more people are flying, and the second is that flying remains almost totally dependent on fossil fuels. We haven't got green technologies available yet for the aviation sector. (In 2019, aviation produced one gigaton of CO2 emissions) And that's roughly equivalent to the total emissions from the UK and Germany combined. BETH BARKER: In 2019, airlines carried around 4.5 billion passengers on flights. and we're really expecting that to grow. (BETH BARKER Project Manager, Aviation Impact Accelerator University of Cambridge) (By 2050, passenger numbers are expected to reach 10 billion a year.) (But not everyone flies...) CAIT HEWITT: Globally, just 1% of the population, many of whom are frequent flyers, generate half of all emissions from the aviation sector. (40% of the population in high-income countries take at least one flight a year...) (...whilst only 1% of the population in low-income countries fly) BETH BARKER: There is no silver bullet to get aviation to become green, but rather a whole set of different options, each with pros and cons. (1. Design tweaks) SILVESTRE PINHO: Winglets are vertical-looking extensions that we've added at the end of the wings. (SILVESTRE PINHO Professor, Department of Aeronautics Imperial College London) And what they do is to increase the efficiency of the wings. These winglets were inspired by birds and we are currently looking at much more features from bird wings and bird flights and incorporating them into our aircraft. (GUY GRATTON Pilot and Professor of Aviation Cranfield University) GUY GRATTON: The aviation industry is really good at making itself more efficient through a mixture of improving technology and learning to fly the aircraft more efficiently. SILVESTRE PINHO: If you look at history, we are improving the efficiency of our aircraft at about 2% per year. That is definitely very little and it cannot continue forever, so we definitely need to change our aircraft fuels. (2. Alternative fuels) GUY GRATTON: Jet engines at the moment run on fuel made from fossil fuels, so it's really important that we find ways to replace that in aircraft. (BIOFUELS) SILVESTRE PINHO: Biofuels are a form of fuel which is made from plant-based materials. The one possible example is vegetable oil, which exists in very large quantities and can be transformed into a biofuel. (But sourcing biofuels is a big challenge) For instance, if we were to replace the entire jet fuel used in the UK with biofuels, we would be using about 68% of the land that we currently use to grow our food. GUY GRATTON: Another possibility is what we call e-fuels, which is scrubbing the carbon dioxide from the air and putting it through chemical processes that turn it back into jet fuel again. So it turns into a circular process where it's all going into the atmosphere and then coming back out again. SILVESTRE PINHO: One big disadvantage of e-fuels is that they are very expensive, not only in terms of their cost, but also in terms of the energy that they use. (What about hydrogen?) GUY GRATTON: Hydrogen is a gas that, if you react it with the oxygen in the air, can release a lot of energy. (H2) That makes it potentially a really good aviation fuel, but it's not without its problems. (Simulation courtesy of Airbus) For a start, we can't store it in the current designs of aeroplanes. Secondly, at the moment, about 95% of our hydrogen comes from fossil fuels. SILVESTRE PINHO: Hydrogen is very explosive, which poses serious safety considerations. (Courtesy of Airbus) Designing, manufacturing and licensing hydrogen-powered aircraft is something that is bound to take decades and cost in the region of tens of billions of pounds. (3. Could planes go electric?) GUY GRATTON: Electric airplanes are still incredibly rare. So, I'm one of the very few people in the world who has had a chance to pilot an electric airplane. (Electric planes are powered by batteries) Whilst it's possible to make an electric car that works well, if you put those same batteries into an airplane, it's simply too heavy to fly. (So, what will it take to make aviation sustainable?) BETH BARKER: There's no doubt that it's going to take a lot of resources, particularly energy. It's going to cost a lot and it's going to require a huge amount of effort from business and from government working together, with the cooperation and support of the public. CAIT HEWITT: It would be great if there was one kind of fix-it-all solution that we could put in place for this sector. Unfortunately, we're going to have to do everything we can think of, and it's all probably going to be quite challenging. SILVESTRE PINHO: A lot of the technologies that we need for greening aviation are still some decades apart. (Flight simulator) They are very expensive, and the electric energy that would be required from a renewable source will also be very expensive and time-consuming to set in place. CAIT HEWITT: Alongside that, just as importantly, we're probably going to have to fly less. Because we've left it so long, there just isn't time left. The aircraft coming off the production line today will probably still be flying in 2050, which is the date by which we have to be at net zero emissions. We need to be building the kind of society in which there are good alternatives to flying. So if you choose to take holiday domestically in your own country, that will start to create that kind of demand that will help make a more sustainable future. INTERVIEWER: Do you fly? CAIT HEWITT: I last took a flight before my daughter was born and she's going to be a teenager this summer.