Biogas upgrading is the process of the separation of methane from the carbon dioxide and other gases from biogas, in order to convert biogas to biomethane, completely comparable to natural gas.
The adoption of the Ministerial Decree of 2 March 2018 represents a fundamental step for development of the biogas / biomethane sector in Italy. Considering an oil price rising today compared to the two years ago and a more and more green optics, the demand for biofuels will always be greater. The new decree aims to boost development of biomethane focusing on an area of intervention considered a priority for the national system: the achievement of the biofuel target to be used in the transport sector by the year 2020. The Decree contains interesting connecting measures with the existing world of biogas in the perspective of allow the current production a progressive alignment to the biomethane sector.
The biomethane production starts from biogas: biogas from anaerobic digesters (wastewater treatment facilities) or from landfill sites contains, in addition to a high percentage of methane, variable percentages of carbon dioxide (CO2), water vapor,
sulfur compounds (hydrogen sulphide), nitrogen, oxygen and siloxanes. In fact, biogas must be purified to eliminate compounds that could damage mechanical components, causing rapid corrosion, wear and malfunction.
ATProX’s activity focuses on the purification of biogas to obtain high purity biomethane, maintaining absolutely competitive plant and operating cost conditions.
Removal of sulphurous compounds (included hydrogen sulfide) is of crucial importance for the technological and economic feasibility of a plant. In fact, hydrogen sulphide is a dangerous and corrosive gas. A high concentration of H2S, for example,
can cause acidification of the lubricating oil, excessive wear of mechanical parts and corrosion of metal components due to the condensation and the formation of sulfuric acid (H2SO4).
Removal of carbon dioxide (CO2) and water vapor is of crucial importance in order to avoid formation of hydrates
(aqueous hydrocarbon structures) that would compromise the operation of the compressors and clog up the pipelines.
Main technologies for biogas upgrading are:
- Absorbtion by mean of solvents, this technology is used in oil&gas sector for large plants
- Adsorption by mean of towers filled with adsorbent material able to “stop” the bulk component
- Permeation by mean membrane.