Innovation provider

BEKON Energy Technologies GmbH & Co. KG

Contact

Feringastraße 9
85774 Unterföhring
Germany
Tel.: + 49 (0) 89 / 90 77 959 - 0
Fax: + 49 (0) 89 / 90 77 959 - 29
E-Mail: kontakt@bekon.eu
Web: www.bekon-energy.de

Description

The BEKON Dry Fermentation process allows treatment of biowaste with a high dry matter content and is highly insusceptible towards undesired contaminants (sand, stones, wooden particles, fibers, etc.). Costly and elaborate dehydration of the digestate after fermentation is not necessary.

Process description
The organic matter is inoculated with substrate that has already been fermented. It is then filled into the digester and fermented under airtight conditions. The further inoculation with bacterial matter occurs by recirculation of percolation liquid, which is sprayed over the organic matter in the digester. No mixing of the organic matter is necessary during the fermentation process like in conventional wet fermentation systems.
The temperature of the process (35 – 38°C) and of the percolation liquid is regulated by a built-in floor heating system in the digester and a heat exchanger in the tank of the percolation liquid.
The different degrading reactions (hydrolysis, acid and methane formation) take place in one digester. This reduces process energy consumption and the maintenance costs. During the fermentation process, no further mixing, pumping or stirring is necessary inside the digester. The highly specialized BEKON process technology of dry fermentation accounts for an extremely low energy input. The gas yields vary depending on the substrate from 100 m³/t for meadow grass (first cut) up to 180 m³/t for maize silage. For organic wastes, gas yields are similar to those of conventional liquid fermentation systems. The low sulphur content and the high methane content in the biogas from the BEKON dry fermentation process are particularly interesting features of this system.

Technical construction
The digesters are made of gastight concrete and can be filled and emptied with a wheel loader. The digesters are elongated and garage shaped, with a large gate on the front. After the biomass has been filled in, the gates are closed and shut gastight. The system is equipped with an especially developed safety device preventing an explosive atmosphere while the digester is opened for emptying and refilling. The generated biogas is dried in a gas-processing chamber, where gas quality and amount are measured. It is then pumped through a gas-regulating device with the respective safety installations into a combined heat and power unit. An especially designed biogas gas engine in the co-generation unit generates electricity. The process heat is partly used for maintaining the optimum temperature in the digesters.

Advantages

Stable, robuste and low cost waste management

  • No pretreatment of the biowaste required.
  • Residuals, e.g. plastic, wood, sand can be handled without problems.
  • No dewatering oft the digestate needed.
  • Simple low cost filling oft the digesters by a wheel loader.
  • Safe use of the wheel loader during the refilling of the digester by means of the upward opening hydraulic doors.
  • The percolate penetrable inner door protects the digester door and the additional drainage plates allow optimal flowout of percolate.
  • Automatic filter systems for the percolate allow low maintenance and reliable operation of the plant.
Stable biological process with maximal biogas yields

  • The inoculation of the fresh mass with the digestated material allows high process stability and maximal biogas yields.
  • Heating system in the floor and in the walls of the digester boxes and in the percolate tank allow short heating time of the substrate and ensure therefore optimal environment for the methanogene bacteria.
  • The computer controlled percolation allows the optimization of the biological degradation in the digesters and therefore maximal biogas yield.
High safety measures

  • The flushing of digesters with the exhaust gas from the CHP units guarantees high safety.
Minimization of the emissions

  • Burning of the gases from flushing of the digesters with a flair system.
  • Collection of the air from the reception hall which is subsequently cleaned via a biofilter.
High energy efficiency based on low energy consumption

  • The electrical energy consumption of the dry fermentation plant reaches less than 3% of the produced electricity (excluding the CHP units and the air conditioning of the reception hall).

Innovative aspects (ecologic, social and economic)


Environmental aspects:

Dry fermentation plant Erfurt

  • The digestate is hygenized on roofed composting area and used in the agriculture.


  • Burning of the gases from flushing of the digesters with a flair system.


  • Collection of the air from the reception hall and cleaned in a biofilter.


  • The electrical energy consumption of the dry fermentation plant reaches less than 3% of the produced electricity (excluding the CHP units and the air conditioning of the reception hall).


  • The water from the  ranking area is collected and added into the percolate tank.




Economic aspects:

Dry fermentation plant processing 15,000 tpa of biowaste

  • Investment costs are specific for each project.


Operating costs:

  • Operating staff: 1 person


  • Renting of the wheel loader plus diesel consumption per year: approx. 20.000 €


  • Maintenance of the CHP unit: 14 € per MWh (electric)


  • The electrical energy consumption of the dry fermentation plant (excluding the CHP units and the air conditioning of the reception hall): approx. 120.000 kWh/a


 
Dry fermentation plant processing 30,000 tpa of biowaste

  • Investment costs are specific for each project.



Operating costs:

  • Operating staff: 3,5 persons


  • Renting of the wheel loader plus diesel consumption per year: approx. 40.000 €


  • Maintenance of the CHP unit: 14 € per MWh (electric)




The electrical energy consumption of the dry fermentation plant (excluding the CHP units and the air conditioning of the reception hall): approx. 200.000 kWh/a

Application examples

Biowaste plants in Germany (Further digestion plants in Italy and Switzerland)
 
Munich

  • 25,000 tpa of Green & Biowaste


  • Electrical power 570 kW


  • In operation as of Nov. 2007




Saalfeld

  • 20,000 tpa of Biowaste


  • Electrical power 1,050 kW


  • In operation as of Nov. 2007




Rendsburg

  • 30,000 tpa of Biowaste


  • Electrical power 1,050 kW


  • In operation as of Nov. 2008




Vechta

  • 10,000 tpa of Biowaste


  • Electrical power 330 kW


  • In operation as of Dec. 2008




Erfurt

  • 20,000 tpa of Biowaste


  • Electrical power 660 kW


  • In operation as of Nov. 2008




Pohlsche Heide

  • 40,000 tpa of Biowaste


  • Upgrading of 500 Nm³/h of biogas


  • In operation as of Nov. 2009




Bassum

  • 18,000 tpa of Biowaste


  • Electrical power 625 kW


  • In operation as of Nov. 2009






Cost

Downloads

Current stage of development

Already on the market

Intellectual Property Rights

Patent granted

Country of origin

Germany

Country of application

Year

2007

National Contact Point

Daniel de Graaf
Umweltbundesamt
Wörlitzer Platz 1
06844 Dessau-Roßlau

Tel. +49 (0)340 21033407
Fax. +49 (0)340 21043407

» daniel.degraaf@uba.de
» www.uba.de