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Forestry byproducts the aviation fuel of the future

Air traffic is responsible for releasing large amounts of carbon dioxide, with increasing passenger numbers placing high demands on technical solutions to reduce emissions. In collaboration with the aerospace industry, researchers are currently developing fossil-free fuels from Swedish forests.

One of the Swedish Government’s environmental goals is that the country should be fossil-fuel free by 2050. Achieving this goal will involve a reduction in carbon dioxide emissions and a major area of focus is the aerospace industry, whose fuel is almost exclusive fossil-based. Researchers at RISE are developing methods and technical solutions for the manufacture of fuels from renewables, including aviation fuel from lignin.

“Wood consists of cellulose, hemicellulose and lignin; the latter being a waste product of chemical pulping and paper manufacture. This lignin is often incinerated to provide process steam and heat; however, it would be a better use of this renewable resource if we were to manufacture biofuel instead,” says Johanna Mossberg, focus area manager for fossil-free transport at RISE.

Emissions can be reduced by 50 percent

If we could replace all fossil-based aviation fuel with biofuel, it would be possible to halve the climate impact of the airline industry. It will be difficult to completely eradicate the climate impact of air travel – among other things due to the high-altitude effects of flying above 10,000 metres, which impact the climate differently and contribute to higher levels of emissions. From a global perspective, we also face another limitation; there is simply insufficient biomass to replace all of the aviation fuel we consume, never mind the fuel used for marine and road traffic. However, for Swedish flights the possibilities are greater. 

“Our domestic flights account for a tiny percentage of total air travel, meaning that Swedish biomass would be more than sufficient for these. From a resource perspective, it would therefore be no problem for us to switch to lignin-based biofuel for domestic flights,” says Johanna Mossberg.

Sweden showing the way

Because Swedish domestic air travel accounts for such a small proportion of total emissions from the airline industry, global carbon dioxide levels will not be noticeably affected, even if we succeed in replacing all fuel used for our domestic flights. However, Johanna Mossberg points out the symbolic value of doing so, rather than the concrete figures for greenhouse gas emissions.

“It is of the utmost importance that we develop new fuels to replace existing fossil fuels. At the rate we currently use resources, we would need four Earths if the entire global population consumed the same amount as us. Sweden must demonstrate that it is possible to change direction, by being at the forefront in developing technologies and expertise that we can then export to other countries. We can then exert real influence and make a real difference!”

The reality in 15 years

One of the challenges in developing biofuels is the economics.

“Aviation fuel is currently tax-exempt, meaning that, unlike the road haulage sector, the industry lacks the economic incentive to change to biofuels. The manufacture of fuels form renewables is an advanced, and therefore more expensive, process. If we can elicit a willingness to pay, then in 10 to 15 years there is every possibility that we will see lignin-based fuels in aircraft fuel tanks,” concludes Johanna Mossberg.