Biofuels for the Aviation Sector

Solution or Perpetual Challenge?

Carbon dioxide emissions of aviation are increasing at two to three percent per year, contrasting international sustainability goals to reduce global emissions by 80 percent during the 21st century. The Air Transport Action Group (ATAG) proposes "climate neutral growth" through energy efficiency improvements, carbon trading, and large scale shifts to biofuels.* In 2050, ATAG envisages 60 to 70 percent of emission reductions to be delivered by biofuels, assuming an 80 percent lower carbon footprint of biofuels compared to fossil oil-based jet fuel.

Biofuels are all fuels made from geologically recent carbon fixation (as opposed to fossil fuels) in all sorts of biomass. Such biomass, or feedstock, may be agricultural products like grains or palm oil seeds, or biological waste (like waste fats, waste from the food industry or forestry by-products). The term ‘agrofuels’ is also used frequently. These are biofuels made from crop or tree feedstocks (as product or by-product). Most biofuels are thus also agrofuels.

But can they be produced sustainably at such a large scale? First generation feedstocks, like sugar or oil seeds, have low spatial efficiency and would require large amounts of agricultural lands, thus competing with food production and creating all the environmental problems that agriculture also causes, including pesticide runoff, water and air pollution, deforestation, and soil degradation. Biofuels are vulnerable to hypes. For instance Jatropha, a ‘wonder bean’ advocated in the 2000s, did not live up to expectations at all. The life-cycle carbon reduction was only 50 to 55 percent, as calculated by Robert Bailis in 2010. Socially, N. Wadhams found in 2009 that Jatropha has caused very negative effects, for example in India and Kenya, depriving local populations of lands for their own food production and not delivering any economic benefits. A 2010 study by P. Ariza-Montobbio even showed Jatropha causing poverty. The failure of Jatropha was already predicted by K. Sanderson in 2009, while the industry kept trumpeting its opportunities in 2011 and still continues to do so in their websites (e.g.

Algae as a new hype

The current ‘hype’ is algae, with high yield claims and the ability to be grown on wastelands in water tanks, thus not competing with food production or natural ecosystems. A European study by J. Skarka published in 2012 showed algae potential in the EU to be limited, because most wastelands are located on too steep terrain. The potential could be 1,000 petajoule of energy, which might cover about 50 percent of current EU aviation energy use, disrespecting the needs of other sectors. Research by L.G. Coplin published in 2012 shows major concerns with algae production, like high water use, low life-cycle emissions efficiency, high nutrients requirements, land use and a range of environmental problems including ecosystem disturbance, air pollution, and toxic substances releases.

No biofuel feedstock has shown competing cost with oil based jet fuel so far. Even the industry, for example the International Air Transport Association (IATA), expects aviation biofuels to become price competitive only in the medium term. Until this moment, aviation emissions growth can only be slowed to a marginal extent, by means of additional efficiency gains (above the normal commercially driven efficiency improvements) and operational measures. Thus, the built-up of total aviation emissions heading towards 2050 is immense.

Waste as an option?

A recent Qantas Airlines report concludes that natural fats and oils waste as feedstock has sustainability problems, while general (agricultural) waste still has major technological problems.

Overall, we conclude that the prospects for large scale biofuel use in aviation to sustainably reduce aviation’s carbon emissions by up to 80 percent around 2050 are very low. Biofuels will certainly not allow for combined emission reductions and unrestrained air transport growth. The latter is the crux of the future sustainability of aviation: unlimited air transport growth is beyond sustainable development.

*The right flightpath to reduce aviation emissions. A position paper presented by the global aviation industry, ATAG, November 2010.…

Paul Peeters is an associate professor at the Centre for Sustainable Tourism & Transport, NHTV Breda University of Applied Sciences, Netherlands, specialising in tourism transport and its impacts on climate change and other environmental issues. Eke Eijgelaar is a principal researcher there, searching for both the impacts of tourism on climate change and ways to mitigate and manage these impacts.

(TW 74, March 2014)