Can we ever really have truly ‘green’ aviation?

Airline seats

Can we even have ‘green’ aviation?  Today’s aircraft burn large quantities of fossil fuels after all – that’s not especially green, let’s face it.

The aviation industry has long had a reputation as a significant contributor to global warming.  Prior to COVID, the amount of air traffic globally had been rising steadily for the past couple of decades.  And, with more traffic, comes more emissions.   

In the future, with many Asian economies continuing to develop apace, we may well see the level of aviation traffic increase even further.  That could well lead to the industry contributing even further to future global warming.

But could it be that new technology can help to deliver a much greener future for this industry? 

The growth of air travel

Before COVID, aviation had witnessed a steady rise in global traffic over the past decade.  Between 2010 and 2019, there has been a 2.7 fold increase in domestic and international passenger flights globally.  This increase was particularly notable in developing economies in Asia.  The trend was clear – as emerging economies become more developed, so the level of air traffic will increase.

COVID, of course, brought this inexorable rise to a sudden halt.  The trend was put into a sudden reverse almost overnight; so much so that global air traffic in 2020 was 34% down on 2019.

But now, as vaccination programmes roll out, we are likely to see air travel recover.  If the longer-term trends are re-established, the next decade is likely to see an ongoing rise in air travel.

So, how much of a problem is it?

In 2019 aviation accounted for an estimated 2.8% of global CO2 emissions.  This may be less than many people might have thought, but it’s significant nonetheless.

Improvements in the efficiency of fuel consumption have minimised the impact of rising aviation traffic to an extent.  Since 2000, despite the overall rise in air traffic, thanks to technology, the level of CO2 emissions has risen by just 50%.  However, these efficiency savings have tapered off in recent years and, without a significant technology breakthrough, further emission increases will inevitably follow any increase in air traffic.

In fact, the level of impact on global warming is potentially more significant than the 2.8% contribution to CO2 emissions.  This is because of what is known as the ‘aviation multiplier’.  Put simply, this reflects the fact that aircraft produce emissions other than CO2 that also contribute to global warming.  The impact of these emissions is less well understood but the discharge of nitrous oxide, water vapour and soot also contribute to global warming.  Thus, the overall contribution to global warming for the aviation industry is likely to be higher than 2.8%.  Estimates vary but it could be as high as 5%-6%.

In a developed economy like the US or the UK, where air travel is more frequent, the true contribution aviation makes to global warming could be a lot higher.  Some have estimated, for example, that in the UK, 13%-15% of the UK’s contribution to global warming comes from air travel.  The same is likely to be true for many developed economies.

At present, the most developed economies account for 62% of aviation CO2 emissions but represent only 16% of the world’s population.

Is there an alternative future?

No doubt aviation engineering will continue to develop more fuel-efficient aircraft.  However, further fuel efficiencies can only go so far, and it is unlikely to be enough to prevent emissions from rising overall.  Some sources estimate that if we continue as we have been, then even with more fuel-efficient technologies, we could see aviation emissions double by 2050.

COVID has temporarily limited the amount of passenger air traffic and forced many would-be business travellers to rely more on remote video meetings by Zoom or Teams.  Perhaps this will mean that many businesspeople will be encouraged to travel less in future.  This might serve to slow the increase in aviation traffic, but it would seem very unlikely that we would see any significant long-term reduction in demand.

If we are to reduce aviation emissions in future, the only realistic answer is likely to come from the development of new, greener, technology.

Electric Planes

We already have electric cars – so why not electric planes?

Actually, we do already have electric planes.

In 2010, Airbus developed the world’s first all-electric, four-engine aerobatic aircraft, CriCri.  Since then, it has developed a couple more, small, electric powered planes that feature vertical take-off capabilities.  The Vahana is a small, single seat, aircraft that has made over 100 test flights.  The CityBus is another small aircraft (capable of seating four) that made its first flight in 2019.

Both these aircraft are small and have a limited range (50 km in the case of the Vahana).  They are a first step but a long way from offering the capability to transport large numbers over long distances.

Airbus have also experimented with hybrid aircraft – combining traditional fuels with electric power in the form of the E-Fan X (based on a 100-seater Bae 146 short-haul airliner).  This was tested between 2017 and 2020 and features a single electric engine used in combination with three conventional ones. 

Whilst a lot was learnt from the E-Fan X project, it is just a first step in the journey to developing a viable hybrid electric aircraft.  The E-Fan X itself is not yet a viable commercial proposition.

Boeing and NASA are also experimenting with hybrids.  The SUGAR Volt initiative represents an ongoing attempt to develop a hybrid plane.  As with the Airbus projects, it is currently at an early stage of experimentation.  One related project is the STARC-ABL (single-aisle turbo-electric aircraft with an aft boundary layer propulsor).  This concept aircraft will have two conventional engines mounted on the wings and an electric engine in the tail. It will be capable of carrying 150 passengers.

The eCaravan

However, if you want to look at a pure electric plane that is capable of flying today, then we need to look at something like the eCaravan.

At the end of May 2021, a modified Cessna, capable of carrying nine passengers took off near Moses Lake in Washington State.  It completed a 28-minute flight, reached a speed of 100 mph and achieved an altitude of 2500 feet.   The plane was the eCaravan.  It was powered entirely by lithium-ion batteries.

At the time of writing the eCaravan is the largest purely electric powered plane ever to fly.

The current limitation (the catch as it were) is, of course, the range.  With the existing configuration it would be possible for four or five passengers to complete a journey of no more than 100 miles.  That is enough for a short hop but clearly not viable for most commercial domestic flights, let alone international travel.

The challenge, at present, lies mainly in the limitations of battery technology.

The Battery Challenge

The challenge we now face is that lithium-ion battery technology is reaching its upper limits.  This has proven enough to enable electric cars to achieve significant performance improvements, but it is unlikely to be sufficient to do the same for aviation.

New, experimental, forms of battery technology may eventually provide the answer. 

The current front runners are likely to come from either silicon anode technology or lithium-metal.  A number of people are looking into developing these but the ones to watch would include Dr Richard Wang of Cuberg and, perhaps inevitably, Elon Musk. 

Musk recently tweeted that he thought he was not far away from having something viable for aviation appliations – “probably 3 to 4 years”.  Cuberg also anticipates making some significant advances over a similar time period.

Perhaps, then, the technology might be there to allow commercially viable electric powered planes to be developed during the late 2020s.  Only time will tell.

Hydrogen Fuels

However, electricity is not the only game in town.

Greener aviation might also be achieved through the development of hydrogen fuelled planes.  This is a technology that Airbus now appears to be focusing a lot of energy on.

In September 2020, Airbus unveiled three new concept planes that would use hydrogen fuel technology: all under the ZEROe brand.  This includes a turbofan design, carrying 120-200 passengers with a 2000-mile range. There is also a turboprop design that can carry 100 passengers with a 1000-mile range and a blended-wing body design that will carry 200 passengers, with a range of 2000 miles.  Airbus believes these concepts can be brought to market at scale by the mid-2030s.

Of course, hydrogen also currently has its issues as an alternative fuel source.  The main barrier is the cost of the fuel – currently high compared to conventional alternatives.  This is likely to change as more industries look to utilise this fuel as a greener alternative.  The other challenge would be to develop the infrastructure needed to produce, transport and store hydrogen fuel at airports.

Looking to the Future

We still have a long way to go before aviation technology has progressed to the stage where greener commercial aircraft with either no or ultra-low emissions are a reality.

However, the technology is now being developed that will eventually deliver that vision.  The question is one of when rather than if.

It is quite possible that within the next 10 to 15 years we will see either electric and/or hydrogen powered aircraft become a commercial reality; enabling us to finally achieve the kind of dramatic reduction in the environmental impact of air travel that we so badly need.

About Synchronix

Synchronix is a full-service market research agency.  We believe in using market research to help our clients understand how best to prepare for the future. 

Helping our clients understand the impacts of new innovations, science and technology markets is a key specialism for us.  You can read more about us on our website.  

If you wish to follow our weekly blog you can view all out past articles on our website here.

Sources

Aerotime

Airbus

Aviation Today

Boeing

Guardian

ICAO

IEA

NBC

Scientific American

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