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Friday, 30 December 2011

The Sustainable Future of Aviation – Biofuel at 38,000 Feet

The ambition to be able to go from anywhere to everywhere probably is as old as mankind. Thanks to technological advances it has turned into more than just a fantasy. Victorian traveller Phileas Fogg still used ships for long passages, but the transformation from journeys for those blessed with infinite patience into global accessibility was down to the aeroplane. Mind you, if you ask people stuck in a queue for security checks at an airport now, they will tell you that everything has gone into reverse and endurance is a desirable trait once more if you want to get farther than the end of your street.

Not that this seems to discourage too many people. Even in these commercially difficult times for airlines some might fail but many survive and the next growth phase for air travel is said to be on the horizon. At the moment the five percent of global carbon dioxide (CO2) emissions that aviation is responsible for looks small in comparison to heating and electricity generation. Once the financial problems in Europe and America will be over, buoyed additionally by demand in growing economies, this will increase, though. So what is someone supposed to do who wants or needs to travel and is concerned about the environment?

‘Don’t fly’, is the straightforward answer some environmentalists give. As usual, it is not that simple. Nothing exists in isolation these days, especially not something extending across the globe like aviation. Drastic changes, therefore, have effects in places far away from the cosiness of board rooms, committee meetings or activists’ gatherings. The travel industry provides millions of jobs, often in places where there is little else.

As this is about renewability, could biofuel help? Increasingly, governmental and non-governmental organisations, airlines and private enterprises appear to think so. Many foster research into alternatives to fossil fuels that is showing tangible results already. Whether that is enough is a different matter.

Aircraft on final


I am not suggesting that the aviation industry is doing all this because it has found its environmental conscience all of a sudden. The odd determined traveller might choose to look for less polluting ways to get from A to B, taking his custom to other forms of transport. However, there are real economic factors that will play a significant part in the question how flying will survive commercially.

Brent Crude oil prices hit a record high in July 2008 at $147 per barrel. For a world that used to moan about less than half that it was a shock. Markets calmed down afterwards but the cost of the raw materials for aviation fuel have crept up again and have hovered around the $100 mark for a while now. Generally, predictions are that we should get used to that, which will mean higher overheads for airlines confronted by their obvious dependency on fossil resources.

At the political end governments have started to raise taxes for air travellers in the name of the environment. In Britain an official website recommends ‘Try to travel less often [by air]’. The real punch, though, was delivered by the European Union (EU) and the European Parliament (EP) when regulations for emission trading were extended to airlines with effect from 1st January 2012. Based on averages from the period 2004 to 2006 CO2 will be limited to a total of 97% of these historical figures in 2012. More importantly, the emissions that are free are capped at 85%. The rest will have to be bought by operators. This has led to protests from countries like America and China that have refused to join this trading directive. A lawsuit filed by Airlines for America was rejected by the European Court of Justice in October 2011. Therefore, all non-EU operators can be included in the trading agreement. Refusal of compliance will result in fines or, eventually, the revoking of licences.

Apart from the obvious opportunity to make more money out of travellers governments have another pressing reason to keep CO2 in check. Rising emissions from air traffic will jeopardise the already shaky reduction of greenhouse gasses many have pledged. For now Europe is leading the field.

People don’t like change, especially if it means they have to pull more money out of their wallets. What airlines and travel operators are afraid of is that a growing number of customers will think twice before they buy a ticket not so much for environmental reasons but because the cheap ‘going from everywhere to anywhere’ we all have become used to will turn into a ‘nowhere without the dosh’.

Carbon Emission Trading vs. Carbon Offset

Please be aware the above mentioned carbon emissions trading (CET) is not the same as carbon offset (CO). CET means charging for pollutants above a certain limit. In contrast, with CO you can pay someone else to do an environmental good deed (e.g., planting trees or setting up solar panels) while carrying on as before.

I used to be very positive about these schemes, as I normally think it is better to take small steps than none at all, but it has become a sore point on which I agree with organisations like Friends of the Earth. For the polluter it is a free ticket to avoid inconvenient adjustments, while there is no guarantee a project that is supposed to counteract the emissions will be carried through or, if so, survive.

From Kerosene to Algae

So the aviation industry has very good reasons to look for alternative, cleaner fuels. Fossil sources

  • are going to run out
  • will become more expensive
  • are constantly at risk of being interrupted by conflict or political upheaval
  • will be used by governments as a political tool

Some figures reveal the size of the problem. The International Civil Aviation Organisation (IACO) estimated in its report Aviation and Climate Change   that globally about 240 million metric tonnes of fuel were burned in 2011. According to the Jet Fuel Price Monitor of the International Air Transport Association (IATA) that added over $60 billion to the bill compared to 2010. When times are tough and money is in short supply that is not what you want to hear if you are trying to keep your planes aloft.

Technical Basics and Challenges

With such a demand biofuels cannot become a total replacement overnight and turn flying into a green tinted magic carpet for the traveller with a conscience. Apart from renewable fuel having its own troubling issues, which I touched upon in my article on biodiesel , the capacities do not exist and research is on-going.

Aircraft engines and fuel

In order to make the specific requirements that aircraft have easier understandable, here is a brief introduction to some technical fundamentals. First of all, there are two basic types of engine.

  • Piston engines
    • These are very similar to the power unit in your car or motorbike
    • They come in normally aspirated or turbo-charged form
    • Fuel is Avgas, Mogas or Diesel (please see below)
    • They usually power propellers
    • Only used in small private and commercial planes or vintage aircraft
  • Turbines
    • Here the combustion process acts on fan blades that either
      • Turn a propeller = Turboprop
      • Or create thrust by accelerating gas = Jet Engine
    •  Fuel is Jet Fuel (please see below)
    • Used in only a small number of private planes but as the main propulsion in many business aircraft and all modern passenger or freight transport

Of course, this is a simplified description but it serves the purpose. The examples above are what you will find most commonly. Types of fuel are:

  • Avgas
    • Short for Aviation Gasoline
    • This is leaded fuel, just as it used be for vehicles
      • 100LL is available with a lower lead content
  • Mogas
    • Short for Motor Gasoline is simply that – petrol as it is in cars
    • Can be used by many piston engines in planes
  • Diesel
    • Once again this is pretty much the same fuel, as you would use in cars or lorries/trucks
    • Especially small sports planes are coming to the market with diesel engines or they are offered for aftermarket fitting      
    • Fossil diesel is very similar to kerosene
  • Jet Fuel
    • Related to, or based on, kerosene
    • Therefore, chemically quite close to diesel
    • Types are
      • Jet A (only available in America)
      • Jet 1A (rest of the world)
      • Jet B (only used in areas with extremely low temperatures)

As you can see, there are a number of substances that can provide the energy for running an aircraft engine. The challenge for biofuel is to replicate the attributes of each one. Consequently, there won’t be just one renewable fuel that will fit all the requirements.

One such quality is to perform at altitude. It might sound obvious but it needs to stay liquid for a start. Jet fuel has a freezing point of -47oC (-52.7oF). Do you think that sounds pretty low and nothing to worry about? Think again! A Boeing 787 Dreamliner has a cruising altitude of 38,000 feet (» 11,600 meters). Sitting on one of the wings you’d enjoy a ‘balmy’ -60oC (-76oF) – not counting the chill factor, of course. Under those conditions anti-freeze additives and heated fuel lines are mandatory in addition to the inbuilt capability to withstand very low temperatures.

With roughly 23,000 commercial planes around the world it is ridiculous to plan for anything else but a straight ‘drop in’ of an alternative fuel, i.e. without having to alter engines and fuel management systems significantly. It will have to match flash point, viscosity, energy content, freezing point and density (weight to volume ratio) if it is to be a viable replacement.

Renewable Alternatives for Aviation

Quite clearly, life is tough at altitude and creating biofuels for that application isn’t as easy as making a straight transition from what we know in other areas, such as cars or household heating. So what is happening? As David Strathan wrote in 2008: “Until recently it was widely thought that using biofuels in aviation was a complete non-starter. The natural freezing point of vegetable oils is too high, so they would congeal at thirty thousand feet, and they contain too much oxygen, which adds weight to the fuel but not energy. But now those technical problems seem to have been cracked. The Finnish oil company Neste has devised a way to produce an oxygen-free biodiesel called NExBTL, which could in theory be applied to jet fuel. And Imperium Renewables {…} has developed a method of reducing the freeze point {…}.”

Biofuel scientist

It might still seem a proposition for the future to the uninitiated but by now, a number of tests (e.g., by Virgin Atlantic) have taken place successfully and commercial flights have covered thousands of miles already. At least, the question whether biofuels are suitable for use in aeroplanes has been answered with a resounding ‘Yes’. Large airlines, including KLM and Lufthansa are actively involved in research and the implementation of practical solutions, as are suppliers like SkyNRG.

Naturally, such fuels cannot come from first generation sources, such as rapeseed or palm oil, because they would have very negative consequences. The focus can only be on second generation supplies and technologies, including waste, although even here caution is recommended. Some raw materials included under the ‘Second Generation’ umbrella, e.g. Jatropha, are fraud with environmental disadvantages.

A better way is something like algae. We know them already as producers of oil that can be converted to biodiesel but there is another surprising way to use them. Why not dry them and use the powder as fuel? Surely, that must be some joke? Apparently not, as the United States Air Force Research Laboratory takes it seriously indeed. Robert Fulton of Compact Contractors for America (CCA) who developed the product was delighted and claimed a lower capital expenditure plus reduced energy requirements as additional benefits.

Dead Duck or ‘Fly Me to the Moon’?

There is no quick way out of aviation’s environmental unfriendliness. It will take years to switch to biofuels and other alternatives completely. In addition production and maintenance processes will have to make use increasingly of renewable energy and recyclable materials. However, to say ‘Stop flying’ is as dumb and short-sighted as resisting change and do nothing. Too much is attached to being connected to the rest of the world for such naïve pseudo-fixes. We have to think beyond slogans and arguments that are bare of any practical solutions.

Yes, we all have to adapt - rich or poor. If someone is hungry the environment is not high on his agenda but if pollution isn’t curbed everywhere the results will usually hit the underprivileged far harder than the affluent parts of the world. However, that is no justification to ride our carbon-neutral zeal on the back of those for whom flying means something completely different to a cheap holiday. Aviation helps to build links – to income, cultural and political exchange, jobs, business and sheer connectedness. Whether it is freight or passenger transport, aircraft create far more than just emissions wherever they go.

Thankfully, it has been proven that biofuels are viable for use in aviation, although, it must not be overlooked that production capacities will compete with demand from road transport and shipping. Only new technologies will help to provide the volumes necessary to sustain air travel now that the basic technical problems have been solved.

Airlines, like other businesses, will only react to political and economic pressure. They are doing this already for three main reasons:

  1. People the world over are becoming more aware of the negative effects that we have on our natural environment. More and more choose to act on this.
  2. These people do not only travel, they also vote. Now that climate change and carbon footprint are topics that have entered the mainstream politicians listen and will take action where they think it is most opportune. Even if that means kicking providers of jobs and tax revenue for now.
  3. Rising costs of conventional fuels are a real headache for operators and have no chance to come down significantly ever again.

Reducing your own travelling by air will certainly help to curtail CO2 emissions but other factors will contribute too. Aircraft are being made more efficient continuously by reducing weight and improving aerodynamics. It must not be overlooked that the industry has taken important steps already. There is even a Sustainable Aviation Fuel Users Group

Keep Calm and Carry On

Are you still sceptical? Well, you should be. As yet, neither are technologies perfected enough nor capacities sufficient worldwide to keep us going on modern biofuels, and the fossil equivalent is running out. However, what if we could just carry on as before but without the environmental cost?

Read here about a fascinating option.


This article has focused on commercial aircraft. I will look at alternatives for General Aviation, i.e. business and leisure flying, in the near future.

I will see you next week




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