Biogas & Biomethane

Biogas is a promising bioenergy alternative to be recovered from organic waste/wastewater in the context of environmental sustainability & circular economy [SD, 2022] , w/ apps including electricity and heat generation, and on-site fuel use.  After biogas purification processes, methane is isolated, reaching concentrations typically above 94% (often exceeding 96%).  The resulting product, known as biomethane, is an important renewable fuel for transportation.  Figure 1 shows biogas & biomethane production flow.

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Biogas

  

Biogas is a renewable energy source composed of a mixture of gases, mainly methane (45-65%), but also contaminants, such as CO2 (30-40%) & H2S (gas composition depends on the type of feedstock & production pathway).  It is produced from raw materials such as agricultural waste, manure, municipal waste, plant material, sewage, green waste, wastewater, and food waste by anaerobic digestion of organic matter in an oxygen-free environment, a proven way & efficient method.

  

A biogas system is typically made up of a biodigester, which are airtight systems (thru the use of containers or tanks) in which organic material, diluted in water, is broken down by naturally occurring micro‑organisms.  In addition to biodigesters, landfill gas recovery systems & wastewater treatment plants are also used to produce biogas.

  

Each normal cubic meter (Nm³) of biogas has a calorific value ranging from 5,000 to 7,000 kcal, corresponding to approximately 5.8–8.1 kWh, which is equivalent to about 0.66 liters of diesel or 0.7 liters of gasoline.

  

Materials & devices used in the construction of biodigesters include coats for gas-holder, piping systems (pipes, valves & accessories), and pumps.  The piping system has to be reliably gas-tight during the life-span of the biogas unit.  Galvanized steel or PVC pipes are most commonly used for this purpose.

  

Biogas in Europe and the U.S.

 

Europe is the largest producer of biogas today: Germany is by far the largest market, home to around two-thirds of Europe’s biogas plant capacity, and accounting for roughly 40% of total European biogas and biomethane production in 2024, at about 9 bcm.  Energy crops were the primary choice of feedstock that underpinned the growth of Germany’s biogas industry, but policy has recently shifted more towards the use of crop residues, sequential crops, livestock waste, and the capture of methane from landfill sites.  In parallel, Denmark, France, Italy, and the Netherlands have actively promoted biogas production, further strengthening Europe’s leadership in this sector [IEA, 2023].

  

In the U.S., the primary pathway for biogas has been through landfill gas collection, which today accounts for nearly 90% of its biogas production.  There is also growing interest in biogas production from agricultural waste, since domestic livestock markets are responsible for almost one-third of methane emissions in the U.S. (USDA, 2016).  The country is also leading the way globally in the use of biomethane in the transport sector, as a result of both state and federal support [IEA, 2023].

  

Almost 2/3 of biogas production in 2018 was used for electricity & heat, with an approximately equal split between electricity-only facilities and co‑generation facilities (Figure 2).  And, in short, in Europe most biogas production today comes from crops; and in the U.S., from municipal wastewater (Figure 3). Biomethane, in turn, is produced by upgrading biogas and represents a major source of future growth, with around 90% (100% in Brazil) of current biomethane output originating from biogas upgrading.

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Biogás in Brazil

  

According to the CIBiogás Panorama 2024, biogas feedstocks in Brazil are classified into three main categories: i) agricultural & livestock residues (animal manure and farming effluents), ii) agroindustrial waste (industrial effluents and organic by-products from food, biofuel and processing industries), and iii) sanitation & urban waste (municipal solid waste (MSW), food waste & wastewater).  These three streams form the backbone of Brazil’s biogas supply chain [CIbiogas, 2025].

  

In 2021, the agricultural sector accounted for 80% of the biogas plants in operation in Brazil, while the industrial and sanitation sectors represented 11% and 9%, respectively. In terms of production volume, however, the sanitation sector dominated, contributing 74% of total biogas output, followed by industry (16%) and agriculture (10%)

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Biomethane

  

One possible use of biogas is in the form of biomethane, a.k.a, renewable (or sustainable) natural gas (RNG).  The methane (CH4) content of biogas typically ranges from 45% to 75% by volume, with most of the remainder being CO2.  Biomethane is obtained by upgrading biogas, which could be a major source of future growth (around 90% of today’s biomethane production is from upgrading biogas).

 

Although most of the biomethane production comes from upgrading biogas (using feedstocks described above), the gasification route to biomethane can use woody biomass (in addition to MSW & agricultural residues) as a feedstock, which consists of residues from forest management and wood processing.  Most biomethane production today is in Europe and the U.S., although these regions upgrade only a small share of their overall biogas output [IEA, 2022].

  

Only biomethane is considered suitable for use in the transport sector.  The U.S. is also leading the way globally in the use of biomethane in the transport sector, as a result of both state &federal support [IEA, 2022].

  

Key Takeaways

  

The rise of biogas has been shaped by two main factors: Policy support and feedstock availability [IEA, 2022].  Biogas & biomethane today account for less than 3% of total bioenergy demand, and represent an even smaller 0.3% share of total primary energy.  However, global combined biogas & biomethane production is expected to grow by around 22% between 2025-2030, reflecting strong medium-term expansion prospects [IEA, 2025].

  

In Brazil, Raízen (RAIZ4) plans to build biogas units in all its sugar & alcohol plants (nearly 40) by 2030 (w/ a budget of BRL 300 million per biogas unit), where the (bio) gas will be produced from sugar-cane waste (vinasse & filter cake) [PH, 2022].

  

Biogas & biomethane can play an important part in waste management, improving overall resource efficiency.  Where it displaces gas transported or imported over long distances, biogas & biomethane also yield energy security benefits.  Brazil’s biogas sector ended 2024 with 1,587 operational plants, representing an 18% year-on-year increase, and total production reached 641 Mi Nm³. Although biomethane production in Brazil remains incipient, it is highly promising: in 2024, the country had 54 operational plants, with an installed capacity of 2.7 Mi Nm³ by year-end [CIBiogás, 2024].

  

There are also broader non‑energy considerations, such as nutrient recycling, rural job creation or reductions in the time spent in low-income communities collecting firewood.  Both biogas and biomethane can also be developed at scale thru partnerships btw energy & agricultural industries.