Biofuels on organic farming

Summary

Organic agriculture is one sustainable alternative to avoid negative environmental effects often caused by conventional agriculture. The area for organic farming in Europe is increased rapidly in the last decades and Denmark is one of the top-ten countries in Europe as regards the organic share of the total cultivated area.
The production of bioenergy from local biological resources and the maintenance of soil fertility seem to have been opposing aims in organic agriculture. In organic farming, there is a strong effort to reduce the reliance on fossil fuels and decrease greenhouse gas emissions in organic agriculture.
Cheese whey is a by-product from the dairy industry, which has the highest market share of organic foods in Denmark. It generates approximately 9 l of cheese whey for each kilogram of cheese produced, yielding an important source of environmental pollution all over the world. However due to its valuable sugars (lactose) content production of bioethanol as a valuable resource represents an alternative way.
The aim of our study was to find the best way of utilizing whey and to design a process for conversion of organic whey into bioethanol by fermentation using Klyveromyces marxianus yeast strain. Ethanol production by K. marxianus in different kinds of whey from organic cheese production was examined. The results showed that pasteurization was not necessary prior to the process, which is a great advantage from an industrial point of view. Batch and continuous fermentation with immobilized yeast were also performed with high ethanol yield.
Other cereal products from organic farming were also involved in our research by applying inherent autoamylitical enzyme activity. Whey permeate was incorporated into the grain Simultaneous Saccharification and Fermentation (SSF) process by using as a cheap nutrient source. The fermentation efficiency by inherent enzymes was 60% of the theoretical, only 10% lower when commercial enzymes were used.
The presented process is planned to be part of developing a concept for a decentralized biorefinery concept to be used in the organic agricultural industry in Denmark, by integrating energy production (biogas and bioethanol) in organic farming to increase the sustainability and self-reliance of energy utilized in this industry. Therefore effluent from ethanol production was further studied in biogas experiments. Co-production of these two biofuels in coordinated bioenergy plant seems to be an optimal solution for organic farms. New innovative process configurations, like linking of bioethanol and biogas production can be resulted in (1) reduced production costs, (2) less utilization of fossil energy sources, (3) the reuse of excess materials and by-products of employed technologies and (4) increase a sustainability of the organic farms.