Biogas vs Biomethane

From biogas to biomethane

Biogas is mostly made up of methane (between 50-70%) and is produced by the digestion of organic waste from agricultural biomass (dedicated crops, by-products, agricultural waste and animal manure), agro-industrial biomass (waste from the food processing chain), industrial processing waste, municipal wastewater sludge and organic fractions of municipal solid waste (OFMSW).

Biomethane is a biogas that has undergone a refining process to get a concentration of methane equal to or greater than 97%, which can be used in the same way as natural gas by being injected into the network or as biofuel in gaseous or liquefied form for transportation.

How to make biomethane

The conversion from biogas to biomethane occurs through a process of upgrading, which removes carbon dioxide through a multi-step molecular separation process. The various stages of the process (pre-treatment, dehydration, compression, etc.) are optimised depending on the upgrading technology chosen and the composition of the biogas to be treated.

In addition to carbon dioxide, other gases are also removed, such as hydrogen sulfide, ammonia, siloxanes, volatile organic compounds (VOCs), contaminants and other inert substances present within the biogas. It is essential to remove these substances because, if they remain present, they could give rise to different problems: they could end up being released into the atmosphere, or they could remain in the biomethane and alter its quality specifications, as well as affect the proper operation of the plant itself. In addition, the presence of VOCs leads to negative effects on the odorability of biomethane.

What happens after biogas upgrading

Biomethane obtained after the upgrading phase is eligible to undergo the various stages of controls over the quality, metering, compression, regulation and possible odorisation. These stages must necessarily be completed before one of the possible next stages:

  • Network injection stage – it could be transport or distribution network – to be executed in compliance with the specifications laid down by the applicable legislation. This stage requires dedicated solutions
  • Production of liquefied biomethane (LNG), which requires dedicated quality analysis and fiscal metering solutions

Focus

Biomethane
Unlike other renewables, biomethane requires limited investment in terms of infrastructure. Moreover, regarding emissions, it is considered to be neutral as it is produced via the digestion of biomass from by-products, industrial processing waste and organic material. Specific incentives promoted at the European level are making its use economically sustainable, and as a result production and use of this source are being strongly encouraged.
PF experience in biomethane

Pietro Fiorentini realises integrated and customised solutions along the entire biomethane chain, including the treatment of raw biogas, the feeding of biomethane into the grid, methane and CO2 liquefaction. Pietro Fiorentini is a member of the Board of Directors of the Italian Biogas Consortium and is founding member of the Biomethane Industrial Partnership.

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Biomethane: the advantages of this gas

Biomethane is a valuable ally in the energy transition process: it is a sustainable gas produced from the digestion of biomass, a raw material considered as waste that starts a virtuous circle in which the final by-product also finds a new use.

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