With people taking more flights than ever and the air industry set to grow, can tech advances really help us achieve net zero?

When you think about things that are quintessentially British, you probably would not immediately put “flying” into that category – but you should. We Brits don’t just like flying, we love it.

Data from the International Air Transport Association (IATA) shows that more Britons flew abroad last year than any other nationality. Roughly one in every dozen air passengers was British. Britons took to the skies 126.2m times in 2018, beating Americans and Chinese people into second and third place. Needless to say, this comes at an environmental price.

The UK aviation industry pumped 37m tonnes of carbon dioxide (CO2) into the atmosphere last year alone. That’s about 4% of the 918m tonnes that the global aviation industry emitted in 2018. And it’s an upward trend. The aviation industry is currently growing at between 4% and 5% a year, at which rate passenger numbers will double every 15-20 years.

“UK CO2 emissions from aviation have doubled over the last 20-25 years and are predicted to grow into the future,” says Tim Johnson, the director of the Aviation Environment Federation, an environmental campaigning organisation that represents communities who are affected by noise and emissions, primarily around UK airports.

The problem this creates for the aviation industry is acute, especially since in June 2019, the UK government signed into law a commitment to make the UK a “net zero” greenhouse gas emitter by 2050. By “net zero” this means that any greenhouse gases that are still used will have to be offset in some way. Schemes include buying and preserving parts of the world’s rainforests or planting new trees somewhere in the world, or more radical technology to literally pull the CO2 out of the air.

Currently, aviation is responsible for about 2.5% of the world’s CO2 emissions. That may seem a small percentage, but this share of the total could increase significantly with the expected growth of air travel and the drive to greener operations in other industries. Accordingly the industry is looking to technology and engineering to help make aircraft more environmentally friendly. At the forefront of this is the electric engine.

Facebook Twitter Pinterest The Airbus E-Fan X, a collaboration between Rolls-Royce and Airbus, is an electric hybrid test aircraft with one electric and three kerosine engines. The plan is to develop a 100-seater electric hybrid short-haul plane that could be operational in the 2030s. Photograph: Airbus S.A.S

Electric engines for aircraft come in two forms. Rather like their motor car equivalents, there are hybrid electric engines, which would still burn fuel but can switch to battery power when appropriate, and there are fully electric engines that derive all their power from batteries.

To Rob Watson, director of Rolls-Royce Electrical, the move to electric engines is a revolution that will usher in not just a more sustainable industry but a whole new era of flight.

“A third era in aerospace is emerging around us now, and it is enabled by electrification,” he says. “From our perspective, it’s a really exciting opportunity for us to help pioneer this third era.”

According to Watson, these eras of flight are driven by the available engine technology. First, it was piston engines to drive propellers, then it was jet engines, and now the electric engine promises to bring savings in both operating costs and environmental impact.

“We are determined to play the part that you would expect from a company with Rolls-Royce’s engineering pedigree,” says Watson.

To that end, Rolls-Royce has partnered with Airbus and Siemens to develop the E-Fan X, the latest in a series of hybrid electric demonstration aircraft. Following the successful flight of the E-Fan, a two-seater fully electric aeroplane that flew across the English Channel in 2015, the E-Fan X project received a large share of the £255m that the government committed to investment in the field last year, and is on course to begin test flights in 2021.

This time instead of a fully electric personal plane, the company is adapting a small commuter aircraft based on the BAE 146 design into a hybrid electric. One of the aircraft’s four engines will be replaced with an electric engine running off batteries.

“It is going to be the highest power hybrid electric aircraft that we have flown,” says Glenn Llewellyn, VP of zero emissions technology at Airbus. Following this, Llewellyn imagines one more test plane to demonstrate full electrification of all the engines, and then the plane can enter service.

The bottom line is clear: long-haul flights will have to use traditional fuel-burning engines

“Our target for the early 2030s is to have zero CO2 emission aircraft. This means completely eliminating CO2 per passenger,” says Llewellyn. To do this, he explains that the electricity stored in the batteries will come from renewable means such as solar panels and wind turbines.

If all goes to plan, the first all-electric flights are likely to be small, island-hopping journeys, progressing to domestic and then short-haul flights. But unless there is a major breakthrough in the amount of charge a battery can hold, the batteries will simply be too heavy and take up too much space to be practical for long-haul flight.

The bottom line is clear: however you approach the problem, long-haul flights will have to use traditional fuel-burning engines. But that doesn’t mean they will need to use the traditional fossil fuel, kerosine. Airlines are developing and testing Safs – sustainable aviation fuels.

Facebook Twitter Pinterest Nasa’s all-electric X-57 Maxwell replaces combustion engines with 14 electric motors. The first test flight is planned for 2020. Photograph: Nasa

When the industry began investigating these a number of years ago, it was first thought that they would be biofuels, extracted from crops or plants, such as palm oil. However, the temptation of local farmers to cut down tropical rainforest to plant palm trees to sell to the fuel companies has seen airlines withdraw pretty quickly from that route. Instead British Airways and a number of others are turning to something that we make far too much of every day: rubbish.

The fuel produced by chemically processing this rubbish is an artificial kerosine. Present rules allow it to be mixed in a 50/50 ratio with fossil kerosine. This is unlikely to change because the fossil kerosine contains naturally occurring chemicals that cause the rubber seals on a jet engine to swell, making them tight. Engine manufacturers rely on this process to make the engines Safe. Artificial kerosine does not contain these special molecules in anything like the same quantity and so cannot be used exclusively in current engines.

Even if they could, Tim Johnson is sceptical that Safs would make a real difference. Last year, 7m litres were used on flights. “That sounds like a reasonable amount by volume but it’s enough to power the global aviation industry for 10 minutes,” he says, “so in terms of scaling up Safs, we’re a long way from making that a reality.”

The airlines make money through volume. This means the growth of the industry is essential

Added to this, they are twice the price of ordinary kerosine – a cost airlines may have to pass on to their passengers.

There are other things that airlines and aircraft designers may be able to do to increase carbon efficiency. More effective air traffic control could prevent aircraft having to take detours to avoid congested skyways. Better wing design could reduce the drag of aircraft. Better carbon fibre manufacturing techniques could result in lighter airframes. And airlines could always squeeze more seats in. All of these together can offer small percentage-level improvements that will contribute towards reaching the 2050 target.

It remains a big challenge, however, with a lot of risk. A delay in any one of the proposed technologies coming online, such as the electric engines or the sustainable aviation fuels, could torpedo any hope of hitting the net zero carbon emissions the law requires by 2050. If it becomes clear during the next decade that the target is unreachable on the current trajectory, some real pain may have to be endured by the industry and the people who use it.

At the heart of the predicament is the fact that the airlines operate on very small profit margins, making their money through volume. This means that the growth of the industry is essential, yet this very growth is the chief obstacle in halting the environmental impact. At present, technological innovation is delivering a 1% per annum saving in carbon efficiency, but this is completely outstripped by the industry growing at 4-5% a year.

Unfortunately, says Johnson, carbon offsetting schemes are little more than a temporary fix. Those schemes rely on some form of preserving or planting trees, but as the 2050 deadline approaches, all the countries we traditionally use for carbon offsetting, such as India, China and others in South America, are going to need those hectares to offset their own rising carbon emissions.

“This is the fundamental obstacle to us reaching our environmental objective,” says Johnson. “If this industry were static in terms of people flying, all the improvements we’ve discussed would be improving the industry on an annual basis.”

Facebook Twitter Pinterest Eviation Alice was unveiled at this year’s Paris air show. The Israeli manufacturers claim it is ‘the world’s first all-electric commuter aircraft’. Photograph: Eviation Alice

But they’re not. And that means only one thing according to Johnson: restricting the demand for air travel. It’s a conversation that an increasing number of people may already be having with themselves. The Swedish concept of flygskam or “flight shame” entered the lexicon this year. The Swiss bank UBS surveyed 6,000 people in the US, Germany, France and the UK and found that 21% of respondents said they had cut the number of flights they took during the last 12 months.

A 2014 survey of 1,000 UK residents revealed that just 15% of Britons were responsible for 70% of flights and this led to calls for a frequent flyer tax. Some sort of carbon pricing scheme has also been suggested by the Energy Transitions Commission (ETC), an international organisation dedicated to roadmapping ways to a low carbon future. Under such schemes, carbon could be priced at up to £200 per tonne, and a proportionate contribution added to each plane ticket.

Even if passengers in the west do think more carefully about flying, and the price of tickets goes up to deter them further, the decrease in passenger numbers will probably be outstripped by rising demand in developing economies such as India and China. That means globally the number of us flying will still rise, and that means to achieve net zero by 2050, airlines may have to expand into the carbon capture market, developing commercial technology to pull CO2 out of the atmosphere.

Such technologies do exist but they are small-scale devices used to keep the air breathable on submarines and spacecraft. To scale these up to something capable of making a global impact will require serious investment in green startup companies and probably government incentives. To delay the investment in this technology almost certainly means having to abandon net zero carbon emissions by 2050, or the introduction of draconian measures to limit air travel in the coming decade, no matter what economic damage that does to the aviation industry.

When it comes to aviation and the environment, one thing is certain, says Johnson. “We are going to have to have difficult conversations about how we hit our net zero targets.”