The watery residue from bioethanol production used to be disposed of on farm fields. Verbio, a Leipzig-based bioethanol producer, is now using it in a new procedure to produce biomethane in natural-gas quality as well as organic fertilizer. The company has thus added two new, high-quality products to its portfolio while improving its greenhouse balance sheet. 12/2010

Verbio is the first producer in the world to combine on a commercial scale the production of bioethanol with the generation of biogas and organic fertilizer. It does this at its Zörbig plant, which produces 90,000 tons of the biofuel from grain annually. The watery residue, or so-called stillage (Schlempe), used to be mixed with liquid manure and spread on crop land. But the company is now using a state-of-the-art fermentation plant to turn its stillage into biomethane. Nitrogen and other minerals are isolated in the process and made into raw materials for fertilizer production. The biomethane produced is refined to natural-gas quality then fed into the network of regional supplier Mitgas.

Verbio plans to produce 240 gigawatt hours of biomethane annually in the start-up phase and later increase production to 370 GWh. The new procedure is helping the company make a clear improvement in its greenhouse balance sheet in bioethanol production, ensuring that it meets the requirements of Germany’s new Biofuel Sustainability Ordinance. At the same time it is adding two new commercially viable products to its portfolio: biomethane and organic fertilizer. The German Energy Agency dena has honored Verbio with its “2010 Biogas Partner Innovation Prize” for this concept.

The integrated procedure has likewise been implemented by Verbio at its second bioethanol plant in Schwedt. Thirty million euros were invested at each site for this purpose. Verbio has already found customers for its biomethane: the energy suppliers Eon Bioerdgas and Lichtblick, as well as Munich City Utilities (Stadtwerke München - SWM). SWM mixes this relatively environmentally friendly fuel with fossil fuels at its nine natural-gas filling stations at no added cost, creating a fifty-fifty blend. The carbon balance sheet of vehicles running on this blend is supposed to improve by up to 60% compared to gas and diesel burners.

A more detailed version of this article is available in German. To order an English translation, please use the contact form.

Read also:

Biomethane in every corner of Europe

Energy efficiency is becoming a competitive factor

Solar modules head for grid parity