Development Of Sustainable Heat Markets For Biogas Plants In Europe

European Biogas Association’s position on digestate drying

May 23rd, 2013 | Posted by admin in News - (Comments Off on European Biogas Association’s position on digestate drying)

In several European countries effective use of the heat  generated during processing of biogas to power is obliged  by law  and/or supported  by public funds.  In this context,  EBA would like to  draw attention to  possible unnecessary wasting of heat in the digestate (fermentation residue from the anaerobic digestion process) drying process, which could be considered as economically justifiable heat consumption eligible for funds.

Drying of digestate is a relatively old technology  and  was  first  introduced  (and tested)  in  1980‘s.  The technology was supposed to  transport  concentrated mineral content  of digestate  from areas with intensive agricultural production to areas with shortages of organic and mineral supply in agricultural land.  However, this concept was shortly rejected because of the dramatic reduction of nitrogen content during drying , which resulted in the degradation of fertilising effect of the digestate.

Nowadays,  we  observe  an effort to reintroduce the digestate treatment technology  in several countries in Europe.  This phenomenon  is  related  to  an artificial  promotion  or obligation to use heat produced at biogas plants. The technical, economic and environmental scarcities of digestate drying are presented here .