Stable operation of biogas plants through the use of sugar-beet slices

‘Novy Dvor’ and ‘Vrbina’ are the flagship plants of EnviTec Biogas AG in Slovakia. The special feature of the two biogas plants situated close to Bratislava is the fact that their input contains a large proportion of sugar-beet residue, which is a waste product created by the nearby sugar factories. The sugar-beet residue makes up two-thirds of the input material that is fed into the 1-MW plants, while the remaining third consists of maize silage and manure. Both plants were designed to run on an input mixture consisting purely of corn and manure. This was the input material that was used to activate the plants. Thanks to the flexible input-technology of the EnviTec plants, ‘adapting’ them for an alternative input material was no problem.

‘Alternative input materials such as sugar-beet slices are interesting with respect to every single market, as they reduce the raw material costs’, according to Christian Ernst, who is a sales manager at the industry leader from the town of Lohne in Niedersachsen. The two biogas plants in Slovakia have been using this input-mixture to operate in a stable manner since 2011. Against the backdrop of the fact that the current year is scheduled to see the introduction of new feed-in tariffs in the Czech Republic and Slovakia, the flexibility of the input material represented tremendous foresight on the part of EnviTec: In this case, the legislative authority expects a co-fermentation process to be in play from 2013 onwards, which could be realised, for example, through the addition of production residue and off-specification batches from food industries.

In order to prevent a situation wherein the sugar beets can only be used at the time of the harvest, the sugar-beet slices must be stored properly. In this regard, EnviTec’s Slovakian customers are putting their faith in the technology of hose-silaging. Hose-silaging represents a flexible and economical (compared to the construction of containers) option for storing and thereby conserving, biogas substrates such as sugar-beet slices without using fixed structural facilities. A running hose made from a rigid plastic film is filled with the slices, packaged and set aside. ‘We have been using this storage technique at our ‘Vrbina’ facility over the last two years, and the results have been extraordinary’ states Miroslav Kovácik, director of EnviTec Slovakia s.r.o.

The sugar-beet is taking on even greater significance as an input material for biogas production in the German market. Consequently, some of EnviTec Biogas’s clients operate facilities that run on input materials in which sugar-beets represent a share of 25 percent. The edible root speeds up the fermentation process and thanks to its high sugar content, it degrades faster than conventional input materials. ‘Since the energy is available in the form of pure sucrose and can be converted easily by the bacteria, turnips optimise the fermentation process’, adds Ernst. Thanks to the substrate’s high water content, it is easy to stir. Furthermore, the cultivation of sugar-beets results in a loosening of the crop rotation in regions dominated by the cultivation of maize. However if sugar-beets are to be used, the high sand and stone contents need to be taken into consideration. Consequently the turnips must be cleaned in advance, as clinging sand and stones can interfere with the technology used in the biogas plants.

Two more EnviTec biogas plants are currently being built in Slovakia. However, the company has not restricted itself to construction of biogas plants. EnviTec also runs EnviTec Biogas Service (which is a self-regulating organisation), which operates in the Czech Republic and Slovakia. It is headquartered in Velké Mezirící and is a firm pillar of the services offered by the organisation. The unit has seven employees who are always ‘on call’ and ready to provide reliable and prompt service to EnviTec customers.

About EnviTec Biogas AG

EnviTec Biogas AG covers the entire value chain for the production of biogas: including the planning and turnkey construction of biogas plants as well as their commissioning. The company takes charge of biological and technical services on demand and also offers full plant and operational management. In addition, EnviTec also operates its own biogas plants. In 2011 EnviTec Biogas established EnviTec Energy GmbH & Co. KG and its 100% subsidiary EnviTec Stromkontor GmbH & Co. KG, expanding its business operations into the direct marketing of upgraded biomethane as well as the marketing of green electricity and balancing energy. Today, EnviTec Biogas AG is represented in 15 countries throughout Europe, as well as in India and the USA. In 2011 EnviTec generated revenues of € 243.9 million and an EBIT of € 10.8 million. The EnviTec Group currently has 470 employees. EnviTec has been listed on the Prime Standard segment of the Frankfurt Stock Exchange since July 2007.