The High Efficiency Digester (HED) is an anaerobic digestion system, available in different sizes depending on the requirements of the farm.

Biogas Technology

Biogas is generated by an anaerobic digestion process, which is the decomposition of organic matter in absence of oxygen by different bacteria. Biogas is produced during three phases.


Fermentative bacteria convert insoluble material as carbohydrates, fats and proteins into soluble substances (smaller molecules). However, some fibrous material cannot be fermented. These can accumulate in the fermenter or pass through the fermenter even though it is intact.


At this stage, the products of the hydrolysis are converted by acetogenic bacteria into acetic acid, hydrogen and carbon dioxide.

Methane formation

The products of the acidification stage are converted into biogas by the methane forming bacteria.

The biogas produced has around 60% methane, 40% carbon dioxide, and traces of water vapor, hydrogen sulfide and ammonia.

This biogas can be introduced into a CPH unit (Combined Heat and Power), to produce electrical energy and thermal energy. The anaerobic digestion process can reduce the odour of liquid manure. The liquid after the digestion, known as digestate, is equal in volume to the initial substrate, but low in odour and with a high content of nutrients.

Therefore, it can be used as fertilizer or dried using the excess heat of the CPH unit to decrease the volume and obtain better storage conditions with high nutrients content.


The system consists of:

  • Pre-dump (for manure storage)
  • Main fermenter
  • Follow up fermenter
  • Storage tank
  • CHP Unit


  • Each fermenter only has one big mixer. Frequency controlled  (15kW connected wattage)
  • Mixing system: Giant paddle mixer (7 revolutions/minute)
  • No pre-dumps (only small storage tank for the daily manure)
  • All fermenters have double membrane roofs
  • Gas storage and desulphurisation inside the fermenter
  • One central pump unit
  • Air controlled valves connected to pipes
  • Mesophilic system operationg; Temperature fermenter: 39°C – 40°C
  • Computer control system; PLC controlled
  • Low energy self consumption (less than 5%)
  • CHP Unit (150-700kWe) 


An important advantage of the HED, is that it can be constructed in different sizes, depending on the availability of the substrates and requirements of the farm.

  • Capacities from 150 kWe to 700 kWe


The High Efficiency Digester (HED) is able to work with several substrates, such as:

  • Animal manure (swine manure, cattle manure, poultry slurry)
  • Energy crops (maize silage)
  • Food waste (food waste from cattle)
  • Organic waste