If you have arrived here it is because you want to know what biogas is and how it is produced.
Biogas is a combustible gas formed from the decomposition of organic matter (biomass), through the action of certain microorganisms.
Biogas is composed of 50-75% methane (CH4), which is the compound that gives it its energy value.
In addition to CH4, biogas is composed of other compounds, mainly carbon dioxide (CO2). The main sources of biogas generation are livestock and agro-industrial waste, sludge from urban wastewater treatment plants (WWTP) and the organic fraction of urban waste (USW).
Where is biogas produced?
Biogas is produced by biological decomposition processes in the absence of oxygen (anaerobic). These processes allow biogas to be produced from organic matter, which commonly occur in landfills or in closed reactors known as anaerobic digesters.
Degassing landfills by capturing the biogas generated allows for improved operating safety conditions in these landfills; in many cases, the captured biogas is also used for energy.
In the case of anaerobic digesters, organic matter (substrates) is fed and certain operating conditions are maintained (residence time, temperature, etc.).
In order to maximize biogas production in digesters, it is common to mix different types of substrates (co-digestion). It is important to take special care to ensure that the mixture chosen allows the biological processes to occur without inhibition.
What are the uses of biogas?
Biogas is the only renewable energy that can be used for any of the major energy applications: electrical, thermal or as a fuel.
It can be used:
- Directly into a boiler adapted for combustion and/or electrical cogeneration.
- Injected after purification to biomethane into existing natural gas infrastructures, both for transport and distribution.
Since CH4 has a global warming potential 21 times higher than CO2, appropriate use of biogas has great potential to contribute to reducing greenhouse gas emissions.
How biogas is produced
As we have mentioned, these bio-reactors produce biogas through anaerobic digestion of organic matter and this process has four phases, according to biochemical and microbiological studies:
Phase I: Hydrolysis
To start digestion, organic materials must pass through a cell wall where hydrolytic agents act. These agents act as extracellular enzymes, converting polymeric material into soluble organic compounds.
Hydrolysis is one of the most careful stages, since it is usually affected by external factors such as pH, the biochemical composition of the substrate, temperature, etc.
Phase II: Acidogenesis
Acidogenesis is the phase in which soluble molecules are converted into simpler compounds. These compounds are then used by methanogenic agents, including hydrogen and volatile fatty acids such as formic, propionic and lactic acids, among others.
At this stage, microorganisms also eliminate any trace of oxygen in the digestion process.
Phase III: Acetogenesis
In acetogenesis, bacteria use other compounds that are not metabolized by bacteria. These include fatty acids, ethanol and aromatic compounds, which are converted into simpler compounds such as acetate and hydrogen.
Phase IV: Methanogenesis
In this phase, methanogenic bacteria act on the above compounds and complement the anaerobic digestion process with the production of methane. 70% of the methane produced in the biodigester results from the decarboxylation of acetate and acetic acid, since only two families of bacteria are capable of using acetate.
SMALLOPS and Biogas
Biogas as a renewable energy has great potential and at Smallops we are working on improving the production of this gas. With a focus on innovation, we have created OPS, zero-valent iron nanoparticles encapsulated in a carbon matrix. The application of OPS in a digester allows the production of biogas in a plant to be increased by 20%, making the biogas generation process more profitable. In addition, iron nanoparticles help to improve the quality of the digestate resulting from production, obtaining better results when applied to soils.
See other applications of encapsulated iron nanoparticles
