Kerosene made from algae oil to make jet fuel sustainable. An article from Aloft - An Inflight Review.
The idea: mix fossil fuel with ever increasing amounts of kerosene from renewable algae. This could significantly improve the carbon footprint of air traffic. Experts say that technological progress in turbine construction or in aerodynamics alone cannot sufficiently reduce the emissions per kilometre flown.
The problem: celebrated a decade ago as renewable resources and as a substitute for all kinds of fuel, oil from rapeseed and other crops is no longer acceptable from an ecological point of view. Huge monocultures have emerged all over the world, damaging biodiversity, destroying the naturally grown vegetation in developing countries, as well as competing with food production. “Fuel instead of food” is a highly undesirable development.
Algae researchers have resolved to change this situation. The experiments are still in their infancy, but Airbus is following this approach with great interest. Their participation in the research has resulted in the establishment of the “Algentechnikum” algae pilot plant, a worldwide unique laboratory located on the Bölkow Campus next to the Airbus premises in Munich-Ottobrunn, which organizationally belongs to the Technical University. The aim is to develop aviation kerosene on the basis of algae biomass.
It appears as though they have thought of everything. The target is a simple technology that can produce the largest possible quantities. The algae will be kept in open basins, will grow twelve times faster than land plants and have a an oil yield thirty times higher than rapeseed and similar plants.
Production will take place on fallow instead of agricultural land. To avoid a conflict over freshwater, they are using “saline algae”, i.e., algae that live in salt water. This resource is available in unlimited quantities along the coasts. Algae farms are also conceivable in nitrogen-rich, over-fertilized waters, or in the vicinity of sewage plants or dairies. From a technical point of view, it is even imaginable to include growth-stimulating CO2 from gas firing facilities or other industrial processes. The water-bound form of carbon dioxide remains available in salt water longer than in fresh water, where it quickly outgases and stops feeding the algae. The claim is that sufficient space is available in southern Europe to cover 30 per cent of the total consumption of kerosene in Europe – 1.7 billion litres a year. The researchers have turned their attention to Greece and Albania in particular. The parameters required are sunlight, temperature and humidity. The basins, open because of the need for sunlight, will be 100 hectares in size. Storm, dust and rain cannot do much harm when farming saltwater algae.
This process is regarded as being particularly robust, whereas farming algae in freshwater would constantly be threatened by such contamination. In addition, the content of the basins does not endanger the surrounding environment; even if living beings were introduced together with the salt water, they would not be able to survive.
The end product is a gooey mass with a water content of 60 per cent. The separation and processing of the oils is effected with chemicals, so-called “green solvents”. Their job is to separate 92 per cent of the oils. The residual materials will be used to produce biogas, hydrogen and methane, which in turn can generate energy. Ideally, no residuals remain from the whole process.
There is no solid information available yet about the CO2 and energy footprint. It is still unclear how much land is needed to produce a given amount of kerosene. The yield after all production steps could be set at 25 grams per square metre. In comparison: if biomass is converted into fuel, the yield is about 2.5 litres per square metre per year. However, an algae harvest cycle is much shorter than that of rapeseed or maize.
More research has to be done to determine which algae strains can achieve this goal. Biologists are aware of a total of 120,000 strains, 37 of which are on the shortlist. To study their growth in more detail, sunlight is simulated on the Bölkow Campus using LED lights. The algae can therefore behave as if they were growing in Hawaii or California. Combined with the current data of a geographic information system, real weather patterns can even be simulated. Under favourable conditions a commercial use could be viable in seven to ten years.
