How food scraps will power airplanes in the future
World's first plant to produce fuel from biogas put into operation
Photo by Kevin Woblick on Unsplash
Reformer, Fischer-Tropsch reactor and electrolyzer combined
To test these approaches in practice and build a pilot plant, the research institutes Fraunhofer IKTS, TU Bergakademie Freiberg and TU Dresden joined forces with the Saxon companies Ökotec-Anlagenbau GmbH, Sunfire GmbH and DBI Gas- und Umwelttechnik GmbH to form a development alliance. Ökotec-Anlagenbau made its existing biogas plant available. There, the partners additionally installed a reformer, a Fischer-Tropsch reactor and an electrolyzer. In the first step, the expanded plant feeds biogas and steam into the reformer, which produces synthesis gas from it - a mixture of hydrogen and carbon monoxide. The Fischer-Tropsch unit then converts this synthesis gas into methane, liquid hydrocarbons and wax. The methane is fed right back into the process to heat the plant equipment. What remains is the wax and the liquid products in a 50:50 ratio. The latter can then be further processed in refineries to produce synthetic diesel or kerosene.
As an alternative and additional source for the synthesis gas, a container is docked with the electrolyzer mentioned above. This is switched on when there is little biogas available or when there is a particularly high supply of electricity from solar or wind power plants. This electrolyzer breaks down water vapor and carbon dioxide into hydrogen and carbon monoxide, i.e. synthesis gas again. It also ensures a continuous supply to the Fischer-Tropsch synthesis plant, which only works really efficiently if there is always enough synthesis gas available.
Producing green electricity or petroleum-free fuels or waxes depending on the market situation
A biogas plant equipped in this way thus has several options for responding to market fluctuations: The operator can continue to convert the biogas into electricity, for example by gas engine and generator, when electricity purchase prices are high. If feed-in tariffs are low, he switches to producing biogenic wax and synthetic fuels. And when plenty of renewable electricity is available, he switches on the electrolyzer.
The petroleum-free fuels and waxes obtained are still more expensive than corresponding fossil-based products. For example, the synthetic fuels and waxes have a production cost of around €2.50 per kilogram. However, the current energy price crisis has already greatly reduced the once immense cost differences compared with petroleum-based products. And even if we assume that prices on the oil and gas exchanges will fall again, the demand for sustainably produced energy sources and materials is growing in many sectors of industry. The airlines in particular are under pressure due to more restrictive environmental protection laws. The German government has announced plans to introduce significant blending of electrically generated kerosene (e-kerosene) with conventional aviation fuel as a mandatory quota from 2026.
Further demand could also come from other sectors in the future, for example from paint and coatings manufacturers, who could use the wax obtained to produce additives. There will also be enough customers in the cosmetics and lubricants industries, says Erik Reichelt. In this respect, biogas plant operators who quickly equip their operations with the new technology can be the first to meet this market demand for biogenic waxes. And if this submarket becomes oversaturated, the wax can also be liquefied into fuel using additional plant technology.
Transfer to industrial scale planned
On the agenda now is the step from the pilot plant to the larger industrial scale. For this transfer phase, Fraunhofer IKTS is currently seeking funding from the structural change support program for the coalfields. In the next stage of the project, a plant capable of producing several hundred liters of synthesis products per hour is to be planned.
Note: This article has been translated using a computer system without human intervention. LUMITOS offers these automatic translations to present a wider range of current news. Since this article has been translated with automatic translation, it is possible that it contains errors in vocabulary, syntax or grammar. The original article in German can be found here.