Go'in Green - Aviation Biofuels

Like many industries today, the airline industry is also looking at ways it can be more environmentally friendly or "green"   Whether driven by a desire to be more corporately responsible or by the pressure of governments, regulatory agencies, or environmental groups, a reduction of aircraft carbon dioxide (CO2) emissions can only be good thing for the earth we live on.

According to the International Air Transport Association (IATA) the airline industry contributes about 2 percent of all CO2 emissions globally. Since 2009, the industry has been working  to cap carbon emissions and improve fuel efficiency in order to cut CO2 emissions by 50 percent relative to 2005 levels by 2050. The main focus of becoming carbon neutral is the use of sustainable aviation biofuels. IATA estimates biofuels could reduce the aviation industry's carbon foot print by 80 percent. 

Photo: United Airlines

To understand what makes an aviation biofuel viable, it is important to understand what makes current aviation fuels practical. Traditional jet fuel is a hydrocarbon derived from the kerosene fraction of crude oil.  Jet fuel has a much higher flash point than gasoline-based fuel, meaning that it requires significantly higher temperature to ignite. It must also have a very low freeze point due to very cold ambient temperatures at altitude.  The two types of fuels used in commercial aviation are Jet-A and Jet A-1. The primary difference between them is the lower freezing temperature of A-1. Specifications for aviation fuels are also very stringent - another big challenge facing the use of biofuels in aviation.

At present the use of biofuels in aviation has been in the form of a few flights using drop-in biofuels, to create a blended fuel containing traditional jet fuel and biofuel. These biofuels have the same properties as jet fuel so they can simply be blended in. These "drop-in" biofuels are known as second generation biofuels or advanced biofuels manufactured from various types of biomass.  Biomass consisting of the residual non-food parts of current crops, such as stems, leaves and husks that are left behind once the food crop has been extracted, as well as other crops that are not used for food purposes as switchgrass, grass, and jatropha, does not affect the world food supply.

As the aviation industry continues to find newer more advanced biofuels there is little doubt that a 100 percent aviation  biofuel  can be produced from sustainable materials. The real challenge is producing it in a cost effective way and on a scale that the industry would require. On the cost side, the economics for the airlines just don't add up.  Even when carbon costs are added to the price of the jet fuel, it is still far cheaper than switching to a biofuel.  According RDC Aviation Economics, at present costs, one tonne of jet fuel emits three tonnes of carbon, the cost of the fuel and the carbon penalty is approximately 700 Euros/ tonne. When compared to the 2200 Euro/ tonne cost of bio-jet fuel  it is  easy to see the economic challenges of switching to a bio-jet fuel.

The second challenge is the scale of production required for the aviation industry. There is almost no chance that biofuels from biomass can be produced at a reasonable cost unless large scale cultivation of non-food sources takes place.  The idea of converting agricultural land from producing human or animal food supplies into fuel production is obviously not possible. Therefore any crop based biofuel must come from land not used for food crops. It must also be able to produce a predictable amount on a regular basis. Jatropha is one such crop that can grow on "marginal" lands however, the crop yield is unpredictable.  Again, the amount of land alone required to produce fuel crops is great and the amount of water required is also huge! 

So will you fly on a biofueled commercial jet soon? The answer is no. There is no doubt that researchers will continue to develop more advanced and reliable biofuels. Airlines will continue to help with the development by the odd flight for research etc. but the fact is, the economics are not here yet. The challenge of balancing the economics of running an airline and the cost to travelling passenger with the current economics of production and scalability of biofuels is just too great. 


Examples of Commercial Biofuel Flights

wikipedia