Biogas production plants for generating electricity
Methanation of waste is an organic process of matter degradation by organic microorganisms.
This process allows a natural transformation of a regular landfill site that receives Municipal Solid Waste (MSW) into a methanation plant.
Methanation happens in anaerobic cells of 50,000 tons, used as bio-reactors. After five years of accelerated maturation and controlled degassing, waste no longer produces biogas or leachate.
The optimization of the degradation process of organic matter leads to a biogas production greater than that of a conventional landfill. Biogas, composed of 55% methane, is a source of renewable energy.
The recovery of biogas through cogeneration gives:
- Electricity (in France equivalent to the consumption of over 2000 households with an installation treating 1,00,000 T/year of waste)
After the full methanation process (4 to 5 years) MSW are extracted from the cell and screening allows segregation and further recovery of:
- metal parts / glass
- plastics (energy recovery) from the final waste,
- and a fine recoverable fraction used as soil enricher.
The total of reclamation rate is more than 70% including the lost mass by biogas production.
Generally a cell is planned to receive around 50,000 tons of daily waste feeding. Once the first cell is closed, the process carries on in sequence for the next five years. After five years the first cell is opened up, the material is screened, inert is sent to the landfill, recyclables are sold in the market and soil enricher is sold or used as landfill capping layer. The same cell is then repaired (even part of the HDPE covering membrane will be reused for the next cycle of MSW treatment) and ready for use again. It will be thus seen that extracting biogas through landfill bioreactor cells is a process allowing valuable land to be reused, without the endless need for always more land.