DESULPHURIZATION. Biogas Bruck produces methane from biowaste for feeding into the natural gas grid as well as fertilizer. Donau Chemie products play a key role in the sustainable recycling cycle.
What Bernadette Mauthner, Managing Director of Biogas Bruck/Leitha, is holding in her hand looks like a horse's tail or a raffia skirt: light beige coarse fibers attached to a piece of metal. It is the exposed inner workings of a filter membrane - perhaps the heart of the biogas plant in Bruck an der Leitha, Lower Austria. The membrane, which costs around 20,000 euros, separates carbon dioxide from the raw biogas so that it can be fed into the gas grid as biomethane.
“We are one of only 14 plants in Austria that process the raw biogas from waste materials so that it is of natural gas quality,” explains Bernadette Mauthner with pride. The plant in Bruck produces 3.3 million m3 of biomethane per year. The sustainable energy is produced by fermenting 34,000 tons of waste from the food and animal feed industry, agriculture and canteen kitchen and cafeteria waste every year. The by-product is 34,000 m3 of fertilizer (“Terra Juva”).
The plant, which was built in 2004, was converted from electricity and heat production to biogas in 2014, when a green electricity tariff expired and electricity generation was no longer economically viable without support.
“Lubricant” for a smooth process
However, the fundamental decision in favor of biomethane was made earlier in Bruck: since 2007, a small pilot plant has been researching whether it is possible to make raw biogas suitable for feeding into the natural gas grid. “A lot of tests were carried out. We saw what needed to be done during processing and what shouldn't be done at all,” recalls Werner Gerhold. The consultant from Donau Chemie Wassertechnik has been working with the Bruck biogas plant since 2009.
Since 2014, he has ensured the supply of a number of substances that are essential in the biogas upgrading process. This is because before the raw gas can be freed from CO₂, it must first be desulphurized. Four substances from three Donau Chemie departments are used: Donau Bellamethan binds the main load of sulphur in the fermenter during fermentation, while caustic soda and hydrogen peroxide ensure fine desulphurization in the chemical-oxidative gas scrubber. Finally, activated carbon removes other volatile organic substances before the gas is pressed under pressure into the membrane for CO₂ separation.
The Managing Director explains why Donau Chemie's products are so important: “Everything we use here in terms of operating materials from Donau Chemie also serves to protect the plant components so that we can operate them safely and well in the long term. It's similar to the oil in an engine. It's definitely worth changing the oil before you have to replace the engine.”
Werner Gerhold says of his job: “My department supplies liquid substances in the order of four to five tankers, each with a filling weight of 23 tons per year. I make sure that the delivery and filling of the tanks runs smoothly and safely.”
A perfect cycle
The efficient, dual use of residual materials as biogas and fertilizer could serve as a model for all biogas plants in Austria, which currently only generate electricity and heat - after all, that's 95 percent. There is only one small flaw, regrets Bernadette Mauthner: “Biomethane is the only renewable form of energy on the market for which there is no support scheme.” A legal basis for feeding biogas into the grid has also been a long time coming.
As a gaseous energy source, methane can be used in many ways, can be stored, is independent of weather conditions and seasons and could therefore make a contribution to greater sustainability and energy self-sufficiency in Austria.
(ALMOST) ALONE AMONG MEN
Bernadette Mauthner is one of very few women in the “biogas scene”. Mauthner's interest in chemistry manifested itself early on. After graduating from HBLVA Rosensteingasse in Vienna, the Lower Austrian moved to Germany, where she studied chemical engineering and completed a master's degree in environmental protection. She worked as a process engineer for large power plants, but at some point decided: “Ten years in Germany is enough”. Back in Austria - after a trip around the world - she had an interlude at Siemens in Linz when someone whispered a tip to her in 2013: “They're looking for a new manager at Biogas in Bruck.”
“My spontaneous answer was: 'No, I'm not interested in that, but I'd like to see what happens there',” says Mauthner. During the quickly organized tour of the company, four of the twelve shareholders “happened” to be present: “That's how the tour turned into a - ultimately successful - job interview.” What initially made Mauthner hesitate was her lack of commercial knowledge: “Up until then, I hadn't had anything to do with economic figures, only with kilojoules. However, I was given the time to familiarize myself with the new role - according to the principle of learning by doing.” Bernadette Mauthner received the ÖGUT Environmental Award in the “Women in Environmental Technology” category in 2018 for her successful work in the circular economy.
graphics: Stefan Diesner Photography