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Decentralized production of bioethanol from sweet sorghum experimental evaluation of the technical and economical feasibility. Development of the ethanol-farm concept within the sweet sorghum European network


To assess the technical and economical feasibility of a decentralized processing of Sweet Sorghum and production of bio-ethanol and co-products (mainly derived from the bagasse). The work will be implemented with strong cooperation with all the other participants of the European sweet sorghum network.
Experimental campaigns have been performed to check the feasiblity of the Sweet Sorghum (SS) industrial processing. The area investigated is the ethanol farm (ie ethanol production) but integrated within the whole network, thus paying much attention to the bagasse. A decentralized approach was also used in the evaluation of the overall flow schemes, and its relevant economics. Only intermediate conclusions can be taken since the general block diagram of the a priori technologies is complex.

The following activities have been carried out;
preliminary technical studies and planning;
small prepilot equipment realization;
experimental campaign for basic data collection;
truck mounted juice concentration unit design and realization production of concentrate by processing juice in a 100 lh{-1} skid mounted concentration unit;
testing of the storage stability of the juice concentrate;
determination of the physical properties and reaction kinetics (concentrates of differing storage times were fermented upon dilution).

The main arrangement of the other integrated activities involved, harvesting, SS varieties preliminary screening, juice extraction equipment and operations arrangement, bagasse specification and dispatching, etc. The sweet sorghum processed was (wray breed) grown in the experimental fields; several varieties have been evaluated concerning sugar yield. The juice has been fermented and distilled and the raw alcohol obtained has been dehydrated by pervaporation. 2 different extraction technologies have been used as well as different flow schemes. The bagasse obtained is to be used as raw material for pulp and paper production.

The SS to ethanol process steps are well known, and considered individually present no particular problems. Nevertheless the feasibility for large integrated projects can be assessed only when the overall system is tested on a large scale.
The project includes the following activities groups :

1) Experimental campaigns for the sugar-juice concentration will be implemented by means of a movable plant, installed on a truck. This unit will be moved to different sites and tests will be carried out. The juices and the concentrated juices obtained will be analyzed and a significant amounts of concentrate will be submitted to storage stability tests in different storage conditions.

2) Pilot facilities will be designed and built to process the concentrated juices in order to obtain fuel-grade ethanol particularly : storage, fermentation, distillation and dehydration units (ethanol-farm). The ethanol-farm will be designed according to the model that will be recognized, after the experimental campaigns, the most suitable for large agro-industrial integrated projects. Experimental campaigns will be carried out to verify the ethanol-farm concept also by processing the concentrates previously obtained and stored.

3) The experimental data collected will be elaborated, in consultation with the European Network Contractors, in order to assess the technical economic feasibility of large integrated project and to define the "Sweet Sorghum best technology" for the European Community.

4) As a complementary activity :
Extensive camera-ready scientific-photographic documentation will be elaborated, collected and provided to the Commission for a specific publication (at a later stage) on the sweet sorghum, as it appears a very promising new crop for the entire European Community.


Costruzioni Industriali Frilli SpA
Località Cusona
53037 San Gimignano Siena