Innovation provider

Estonian University of Life Sciences Institute of Agricultural and Environmental Sciences


Katrin Heinsoo
Riia 181
51014 Tartu
Tel: +372 731 1882
Fax: +372 738 3013


An innovative technical approach was developed to produce solid fuel with improved combustion characteristics through hydrothermal conditioning and mechanical dehydration of the biomass from NATURA grasslands that cause problems in conventional biogas or combustion systems (because of low degradability of hay and its high mineral and nitrogen concentrations).

The mobile bioenergy plant is installed in two standard ISO freight containers which are permanently fixed on a semi-trailer. Technical feasibility of the approach is investigated by the prototype plant that processes about 400 kg silage per day. By means of a screw-conveyer the silage is continuously brought forward to the hydro-thermal conditioning. The conditioner consists of a band-conveyor, on which the silage stays over a defined retention time under constant percolation with circulating mash water at about 40° C. After the conditioning process the biomass is fed into the screw press, where it is mechanically separated into a press cake and a press fluid. The press cake that still contains 50% water is collected in a box for drying to a storable dry matter content of 85%. The press fluid is transferred to the second container into a storage tank. Digestion of the press fluid takes place in three solid-state fermenters. The biogas is used by a burner to produce heat for the water mashing process, the digestion and drying of the press cake. High biogas yield is due to high digestibility of the press fluid. Unused waste heat of combined heat and power plant is prevented through year-round drying of the press cake.


Innovative aspects (ecologic, social and economic)

The PROGRASS project is demonstrating in European regions with a high proportion of extensive grasslands and NATURA 2000 habitats (due to rich diversity in both flora and fauna), not only the feasibility of the innovative approach, but also proves that the approach may become a cornerstone in the protection of these grasslands biotopes by developing a sustainable solution consisting of nature protection and socio-economic development of disadvantaged, marginal rural regions.

Thus PROGRASS will serve to:

  • Protection of NATURA reserves through continuous extensive grassland management with regular harvesting

  • Securing livelihood for small farmers in retreated areas

  • Saving/Compensating costs for the conservation of grassland biotopes

  • Increasing the acceptance for the compulsory and sustainable management and maintenance of these biotopes

  • Promoting distributed, effective and sustainable energy production

European wide creation of awareness and transfer (after testing in PROGRASS partner regions: Germany, Estonia, Wales) of the approach for the sake of European NATURA habitats

Application examples



Current stage of development

Available for demonstration – field tested
Already on the market

PROGRASS is a European demonstration project. As such the main activities will be carried out in Germany, Estonia and Wales. The PROGRASS demonstration plant will be shipped in a double circle round the three project sites within a period of approximately 28 months. After that period the plant will be shipped to interested partner regions that would like to implement the PROGRASS procedure, methodology and technology and to convince regional stakeholders on the spot.

Intellectual Property Rights

Country of origin


Country of application

Germany, Estonia



National Contact Point

Antti Roose
Tartu Ülikooli, Geograafia Osakond
Vanemuise 46
51014 Tartu

Tel: +372 737 6841
Fax: +372 7375825