What Is Biomethane and How Does It Differ From Biogas?
Biomethane is biogas upgraded to over 95% methane, equivalent to natural gas. Key differences from biogas, how it is produced and what it is used for.
Biomethane is biogas that has been purified (upgraded) to a methane (CH4) concentration above 95%, with a quality equivalent to pipeline natural gas. It is obtained by removing carbon dioxide (CO2), hydrogen sulfide (H2S), moisture and other traces from biogas. The result is a renewable fuel that can be injected into the gas grid, used as vehicle fuel (bio-CNG/bio-LNG) or feed industrial processes without the limitations of raw biogas.
The key difference is purity: biogas has 50–65% methane; biomethane exceeds 95%. It is literally the "refined" version of biogas.
Biogas vs. biomethane: the difference in one table
| Feature | Raw biogas | Biomethane |
|---|---|---|
| Methane (CH4) | 50–65 % | > 95 % |
| CO2 | 35–45 % | < 3 % |
| H2S | up to thousands of ppm | < 5–10 ppm |
| Calorific value | ~5–6.5 kWh/m³ | ~9.5–10.5 kWh/m³ |
| Uses | Heat, on-site CHP engine | Gas grid, vehicle fuel, industry |
How it is produced: the upgrading process
It all starts with anaerobic digestion in a biodigester, which generates the biogas. To convert it into biomethane you must remove the CO2 and clean up contaminants. The most common upgrading technologies are:
- Pressurized water scrubbing (PWS): CO2 and H2S dissolve in water at high pressure.
- Pressure swing adsorption (PSA): molecular sieves that retain CO2.
- Selective membranes: separate CH4 and CO2 by permeability; widely used for their modularity.
- Chemical absorption (amines): very high methane purity, ideal for grid injection.
Before upgrading, desulfurization (removing H2S) is essential, because H2S is corrosive and toxic. That is why H2S control is a critical step in any plant aiming to produce biomethane.
Why it matters
Biomethane turns an agro-industrial residue into a tradable, transportable fuel. By matching natural gas, it no longer depends on on-site consumption: it can be sold, injected into the grid or compressed for transport. For a country like Paraguay, with strong agribusiness (slaughterhouses, dairy plants, starch mills, ethanol), it represents a concrete route to energy valorization and to reducing methane emissions, a greenhouse gas far more potent than CO2.
Where it fits in Tech Tank projects
The road to biomethane always starts from a solid base: a well-sized biodigester and stable biogas production. Within its biogas and biodigesters line, Tech Tank integrates the reactor, the gas-holder storage and the covers that stabilize the gas flow before upgrading. To understand the starting point, it helps to review what an industrial biodigester is and the potential of biogas in Paraguay, its regulatory framework and its uses.
Each project defines whether it is better to use biogas on site (CHP) or scale up to biomethane. To evaluate the most profitable route for your substrate and energy demand, contact our engineering team.
Frequently Asked Questions
Are biomethane and natural gas the same?
Chemically they are almost identical: both are high-purity methane. The difference is the origin. Biomethane is renewable (from biomass) while natural gas is fossil. That is why biomethane can replace natural gas in the same applications.
Can biomethane be injected into the gas grid?
Technically yes, when it meets the grid quality specifications. It requires upgrading to over 95% methane and strict control of H2S and moisture. Feasibility depends on local infrastructure and regulation.
How much biogas is needed to produce biomethane?
Since biogas loses its CO2 during upgrading, 100 m³ of biogas with 55–60% methane yields roughly 55–60 m³ of biomethane, with a small methane loss in the process.
Is it worth moving from biogas to biomethane?
It depends on scale, the reference gas price and access to the grid or vehicle market. Small plants usually use biogas on site; biomethane makes sense at larger scale and with secured commercial offtake.
Why must H2S be removed?
H2S is corrosive and toxic: it damages engines, piping and upgrading equipment. Its removal (desulfurization) is a mandatory step both to use biogas in CHP and to produce biomethane.