17 Mar Sustainable flying on poo and food scraps
Research from the American University of California shows that food residues and puddles and poo from animals and humans can be used as jet fuel. By refining the remains, a fuel is created that airlines can mix with kerosene. It would save huge amounts of CO2 emissions for the aviation industry.
‘Wet waste’ is a raw material that is still little used for biofuel. Unlike wood or other biomass, it needs a lot of preparation before it is suitable as fuel; after all, the moisture has to be out before you can burn it.
The researchers found a way to extract the useful raw materials from the wet waste. By fermenting it without oxygen, and stopping the process before biogas is produced, you get fatty acids. These can be used with chemical processes to develop into sustainable jet fuel.
Easy to transport
The advantage of this method: after fermenting, you can transport the fatty acids more easily than the wet raw material itself. You also don’t have to use energy to dry food scraps, poo and manure before using it as a raw material. The researchers see a world where the remains are locally fermented into fatty acids, after which they can go through existing pipelines to central factories, in order to be upgraded to fuel.
The idea could make aviation significantly more sustainable, the researchers believe. According to them, making this fuel is CO2-negative, saving 165 percent greenhouse gases compared to kerosene. It is CO2 negative because manure, human waste and food normally cause CO2 emissions while rotting in a sewer or landfill. By using it usefully, you prevent those CO2 emissions, and although reprocessing to jet fuel costs CO2, it is still a CO2-negative process at the bottom of the line.
In their scientific study, the researchers show in detail how they arrive at the calculations. However, it must be said that there are many optimistic assumptions in the research about the existing infrastructure and the efficiency of the entire process. For example, there needs to be many more bio digesters. That is quite apart from the question of whether aviation would ever switch to this fuel; even the (high-quality) sustainable aircraft fuels that are already there are only mixed with kerosene.