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An introduction to biogas and biomethane

• Biogas supply potential and costs
• Biomethane supply potential and costs
• Outlook for biogas
• Focus: The role of biogas as a clean cooking fuel
• Outlook for biomethane
• Focus: Biomethane and the future of gas infrastructure
• Energy security
• Reductions in CO2 and methane
• Considerations for policy makers

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IEA (2020), Outlook for biogas and biomethane: Prospects for organic growth , IEA, Paris https://www.iea.org/reports/outlook-for-biogas-and-biomethane-prospects-for-organic-growth, Licence: CC BY 4.0

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What are biogas and biomethane.

Biogas is a mixture of methane, CO 2 and small quantities of other gases produced by anaerobic digestion of organic matter in an oxygen-free environment. The precise composition of biogas depends on the type of feedstock and the production pathway; these include the following main technologies:

• Biodigesters : These are airtight systems (e.g. containers or tanks) in which organic material, diluted in water, is broken down by naturally occurring micro‑organisms. Contaminants and moisture are usually removed prior to use of the biogas.
• Landfill gas recovery systems : The decomposition of municipal solid waste (MSW) under anaerobic conditions at landfill sites produces biogas. This can be captured using pipes and extraction wells along with compressors to induce flow to a central collection point.
• Wastewater treatment plants: These plants can be equipped to recover organic matter, solids, and nutrients such as nitrogen and phosphorus from sewage sludge. With further treatment, the sewage sludge can be used as an input to produce biogas in an anaerobic digester.

The methane content of biogas typically ranges from 45% to 75% by volume, with most of the remainder being CO 2 . This variation means that the energy content of biogas can vary; the lower heating value (LHV) is between 16 megajoules per cubic metre (MJ/m 3 ) and 28 MJ/m 3 . Biogas can be used directly to produce electricity and heat or as an energy source for cooking.

Biomethane (also known as “renewable natural gas”) is a near-pure source of methane produced either by “upgrading” biogas (a process that removes any CO 2 and other contaminants present in the biogas) or through the gasification of solid biomass followed by methanation:

• Upgrading biogas : This accounts for around 90% of total biomethane produced worldwide today. Upgrading technologies make use of the different properties of the various gases contained within biogas to separate them, with water scrubbing and membrane separation accounting for almost 60% of biomethane production globally today (Cedigaz, 2019).
• Thermal gasification of solid biomass followed by methanation : Woody biomass is first broken down at high temperature (between 700-800°C) and high pressure in a low-oxygen environment. Under these conditions, the biomass is converted into a mixture of gases, mainly carbon monoxide, hydrogen and methane (sometimes collectively called syngas). To produce a pure stream of biomethane, this syngas is cleaned to remove any acidic and corrosive components. The methanation process then uses a catalyst to promote a reaction between the hydrogen and carbon monoxide or CO 2 to produce methane. Any remaining CO 2 or water is removed at the end of this process.

Biomethane has an LHV of around 36 MJ/m 3 . It is indistinguishable from natural gas and so can be used without the need for any changes in transmission and distribution infrastructure or end-user equipment, and is fully compatible for use in natural gas vehicles.

There are multiple production pathways for biogas and biomethane

Note: Only biomethane is considered suitable for use in the transport sector.

A range of different feedstocks can be used to produce biogas and biomethane

A wide variety of feedstocks can be used to produce biogas . For this report, the different individual types of residue or waste were grouped into four broad feedstock categories: crop residues; animal manure; the organic fraction of MSW, including industrial waste; and wastewater sludge.

• Crop residues: Residues from the harvest of wheat, maize, rice, other coarse grains, sugar beet, sugar cane, soybean and other oilseeds. This report included sequential crops, grown between two harvested crops as a soil management solution that helps to preserve the fertility of soil, retain soil carbon and avoid erosion; these do not compete for agricultural land with crops grown for food or feed.
• Animal manure: From livestock including cattle, pigs, poultry and sheep.
• Organic fraction of MSW: Food and green waste (e.g. leaves and grass), paper and cardboard and wood that is not otherwise utilised (e.g. for composting or recycling). MSW 1 also includes some industrial waste from the food-processing industry.
• Wastewater sludge: Semi-solid organic matter recovered in the form of sewage gas from municipal wastewater treatment plants.

Specific energy crops, i.e. low-cost and low-maintenance crops grown solely for energy production rather than food, have played an important part in the rise of biogas production in some parts of the world, notably in Germany. However, they have also generated a vigorous debate about potential land-use impacts, so they are not considered in this report’s assessment of the sustainable supply potential.

Using waste and residues as feedstocks avoids the land-use issues associated with energy crops. Energy crops also require fertiliser (typically produced from fossil fuels), which needs to be taken into account when assessing the life-cycle emissions from different biogas production pathways. Using waste and residues as feedstocks can capture methane that could otherwise escape to the atmosphere as they decompose.

Most biomethane production comes from upgrading biogas, so the feedstocks are the same as those described above. However, the gasification route to biomethane can use woody biomass (in addition to MSW and agricultural residues) as a feedstock, which consists of residues from forest management and wood processing.

The feedstocks described above were considered in this report’s assessment of the sustainable biogas and biomethane supply potential, and are further discussed in Section 3 below.

Biogas: Most production today comes from crops and animal manure

Biogas production by region and by feedstock type, 2018, the rise of biogas has been shaped by two main factors: policy support and feedstock availability.

The development of biogas has been uneven across the world, as it depends not only on the availability of feedstocks but also on policies that encourage its production and use. Europe, the People’s Republic of China (hereafter, “China”) and the United States account for 90% of global production.

Europe is the largest producer of biogas today. Germany is by far the largest market, and home to two-thirds of Europe’s biogas plant capacity. 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.  Other countries such as Denmark, France, Italy and the Netherlands have actively promoted biogas production.

In China , policies have supported the installation of household-scale digesters in rural areas with the aim of increasing access to modern energy and clean cooking fuels; these digesters account for around 70% of installed biogas capacity today. Different programmes have been announced to support the installation of larger-scale co‑generation plants (i.e. plants producing both heat and power). Moreover, the Chinese National Development and Reform Commission issued a guidance document in late 2019 specifically on biogas industrialisation and upgrading to biomethane, supporting also the use of biomethane in the transport sector.

In the United States , 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 United States (USDA, 2016). The United States is also leading the way globally in the use of biomethane in the transport sector, as a result of both state and federal support.

Around half of the remaining production comes from developing countries in Asia, notably Thailand and India . Remuneration via the Clean Development Mechanism (CDM) was a key factor underpinning this growth, particularly between 2007 and 2011. The development of new biogas projects fell sharply after 2011 as the value of emission reduction credits awarded under the CDM dropped. Thailand produces biogas from the waste streams of its cassava starch sector, biofuel industry and pig farms. India aims to develop around 5 000 new compressed biogas plants over the next five years (GMI, 2019). Argentina and Brazil have also supported biogas through auctions; Brazil has seen the majority of production come from landfills, but there is also potential from vinasse, a by‑product from the ethanol industry.

A clear picture of today’s consumption of biogas in Africa is made more difficult by a lack of data, but its use has been concentrated in countries with specific support programmes. Some governments, such as Benin, Burkina Faso and Ethiopia, provide subsidies that can cover from half to all of the investment, while numerous projects promoted by non‑governmental organisations provide practical know-how and subsidies to lower the net investment cost. In addition to these subsidies, credit facilities have made progress in a few countries, notably a recent lease-to-own arrangement in Kenya that financed almost half of the digester installations in 2018 (ter Heegde, 2019)

Most of the biogas produced today goes to the power sector

Biogas installed power generation capacity, 2010-2018, biogas consumption by end use, 2018, upgrading biogas to biomethane could be a major source of future growth.

Almost two-thirds of biogas production in 2018 was used to generate electricity and heat (with an approximately equal split between electricity-only facilities and co‑generation facilities). Around 30% was consumed in buildings, mainly in the residential sector for cooking and heating, with the remainder upgraded to biomethane and blended into the gas networks or used as a transport fuel.

Today there is around 18 GW of installed power generation capacity running on biogas around the world, most of which is in Germany, the United States and the United Kingdom. Capacity increased on average by 4% per year between 2010 and 2018. In recent years, deployment in the United States and some European countries has slowed, mainly because of changes in policy support, although growth has started to pick up in other markets such as China and Turkey.

The levelised cost of generating electricity from biogas varies according to the feedstocks used and the sophistication of the plant, and ranges from USD 50 per megawatt-hour (MWh) to USD 190/MWh. A substantial part of this range lies above the cost of generation from wind and utility-scale solar photovoltaic (PV), which have come down sharply in recent years.

The relatively high costs of biogas power generation mean that the transition from feed-in tariffs to technology-neutral renewable electricity auction frameworks (such as power purchase agreements) in many countries could limit the future prospects for electricity-only biogas plants. However, unlike wind and solar PV, biogas plants can operate in a flexible manner and so provide balancing and other ancillary services to the electricity network. Recognising the value of these services would help to spur future deployment prospects for biogas plants.

Where local heat off-take is available, the economic case for biogas co‑generation is stronger than for an electricity-only plant. This is because co‑generation can provide a higher level of energy efficiency, with around 35% of the energy from biogas used to generate electricity and an additional 40-50% of the waste heat put to productive use.

Certain industrial subsectors, such as the food and drink and chemicals, produce wet waste with a high organic content, which is a suitable feedstock for anaerobic digestion. In such industries, biogas production can also have the co‑benefit of providing treatment for waste while also supplying on-site heat and electricity.

For the moment, a relatively small but growing share of the biogas produced worldwide is upgraded to biomethane. This area has significant potential for further growth, although – as outlined in subsequent sections of this report – this is heavily contingent on the strength and design of policies aimed at decarbonising gas supply in different parts of the world.

Biomethane: Around 90% of today’s production is from upgrading biogas

Biomethane production and share of total biogas production that is upgraded in selected regions, 2018, most biomethane production today is in europe and north america, although these regions upgrade only a small share of their overall biogas output.

The biomethane industry is currently very small, although it is generating growing amounts of interest in several countries for its potential to deliver clean energy to a wide array of end users, especially when this can be done using existing infrastructure.

Currently around 3.5 Mtoe of biomethane are produced worldwide. The vast majority of production lies in European and North American markets, with some countries such as Denmark and Sweden boasting more than 10% shares of biogas/biomethane in total gas sales. Countries outside Europe and North America are catching up quickly, with the number of upgrading facilities in Brazil, China and India tripling since 2015.

Biomethane represents about 0.1% of natural gas demand today; however, an increasing number of government policies are supporting its injection into natural gas grids and for decarbonising transport. For example, Germany, Italy, the Netherlands and the United Kingdom have all introduced support for biomethane in transport. Brazil’s RenovaBio programme has a target of reducing the carbon intensity of fuels in the transport sector by 10% by 2028. Subnational schemes are also emerging, such as low-carbon fuel standards in the US state of California and in British Columbia, Canada.

The percentage of biogas produced that is upgraded varies widely between regions: in North America it is around 15% while in South America it is over 35%; in Europe, the region that produces the most biogas and biomethane, around 10% of biogas production is upgraded (although in countries such as Denmark and Sweden the percentages are much higher); in Asia, the figure is 2%.

The main co‑product of biogas upgrading is CO 2 , which is produced in a relatively concentrated form and therefore could be used for industrial or agricultural purposes or combined with hydrogen to yield an additional stream of methane. Another option would be to store it underground, in which case the biomethane would be a CO 2 -negative source of energy.

As noted above, the alternative method to produce biomethane is through thermal gasification of biomass. There are several biomass gasification plants currently in operation, but these are mostly at demonstration scale producing relatively small volumes. Some of these plants have struggled to achieve stable operation, as a result of the variable quality and quantity of feedstock. Since this is a less mature technology than anaerobic digestion, thermal gasification arguably offers greater potential for technological innovation and cost reductions. Prospects would be enhanced if incumbent gas producers were to commit resources to its development, as it would appear a better fit with their knowledge and technical expertise.

The rising interest in biomethane means that the number of operating plants worldwide (both biogas upgrading and biomass gasification facilities) is expected to exceed 1 000 in the course of 2020. Around 60% of plants currently online and in development inject biomethane into the gas distribution network, with a further 20% providing vehicle fuel. The remainder provides methane for a variety of local end uses.

For the moment, biogas and biomethane are only a small part of overall bioenergy consumption

Global bioenergy consumption by type of source and sector, 2018, however, there is a strong potential role for biogas and biomethane in the transformation of the global energy system.

Bioenergy accounts for around 10% of the world’s primary energy demand today. It can be consumed either in solid, liquid or gaseous form, and by far the most prevalent use of bioenergy today is solid biomass (around 90%).

The use of solid biomass is typically categorised as either “traditional” or “modern”, and currently demand is split roughly equally between the two. Modern biomass relies on more advanced technologies, mainly in electricity generation and industrial applications, which use upgraded fuels such as woodchips and pellets. Traditional use refers to the burning of solid biomass, such as wood, charcoal, agricultural residues and animal dung, for cooking or heating using basic technologies such as three-stone fires. With low conversion efficiencies and significant negative health impacts from indoor air pollution, many developing economies are trying to shift consumption away from traditional use.

The differentiation between traditional and modern does not apply for liquid and gaseous bioenergy, since both are produced using advanced technologies. Liquid biofuels make up around 7% of total bioenergy demand today. Biofuels are the main renewable energy source used directly in the transport sector, with around 90 Mtoe or almost 2 million barrels of oil equivalent per day consumed in 2018. About 70% of biofuels consumed today is bioethanol, which is usually blended with gasoline; most of the remainder is biodiesel.

Biogas and biomethane today account for less than 3% of total bioenergy demand, and represent an even smaller 0.3% share of total primary energy. But there are reasons to believe that these low-carbon gases could gain a firmer foothold in the future.

• They can provide the system benefits of natural gas (storage, flexibility, high-temperature heat) without the net carbon emissions. As economies decarbonise, this becomes a crucial attribute.
• Biogas provides a sustainable supply of heat and power that can serve communities seeking local, decentralised sources of energy, as well as a valuable cooking fuel for developing countries.
• The GHG reduction benefit is amplified by the processing and use of methane (a potent GHG) that could otherwise be released to the atmosphere from the decomposition of organic by‑products and waste.
• Biogas and biomethane can also play an important part in waste management, improving overall resource efficiency.
• Where it displaces gas transported or imported over long distances, biogas and biomethane also yield energy security benefits.
• 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 through partnerships between the energy and agricultural industries. By transforming a range of organic wastes into higher-value products, biogas and biomethane fit well into the concept of the circular economy.

Policies can help to unlock these benefits, but much will depend on how much biogas and biomethane is available and at what cost. These are the questions addressed in the next section.

MSW can either feed a biodigester or be disposed in landfill to produce landfill gas.

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Biogas from biomass

Biogas, which may be called renewable natural gas (RNG) or biomethane , is an energy-rich gas produced by anaerobic decomposition or thermochemical conversion of biomass. Biogas is composed mostly of methane (CH 4 ), the main compound in fossil natural gas, and carbon dioxide (CO 2 ). The methane content of raw (untreated) biogas may vary from 45%–65%, depending on the material (feedstock) used to produce the biogas. Raw biogas can be burned directly as a fuel for heating or for generating electricity for onsite use or for sale to the electric power grid. Raw biogas must be treated to produce RNG before it can be used in place of fossil natural gas. RNG can be used to produce compressed natural gas (CNG) or it can be injected into natural gas pipelines. Treatment includes reducing nitrogen and oxygen content and removing moisture; CO 2 ; and trace amounts of siloxanes, volatile organic compounds, and hydrogen sulfide. The resulting RNG has a methane content of at least 90%. RNG injected into natural gas pipelines has a methane content of 96%–98%.

Anaerobic decomposition of biomass occurs when anaerobic bacteria—bacteria that live without the presence of free oxygen—eat and break down, or digest , biomass and produce biogas. Anaerobic bacteria occur naturally in soils, in water bodies such as swamps and lakes, and in the digestive tracts of humans and animals. Biogas forms in and can be collected from municipal solid waste landfills and livestock manure holding ponds. Biogas can also be produced under controlled conditions in special tanks called anaerobic digesters . Digestate , the material remaining after anaerobic digestion is complete, is rich in nutrients and can be used as a fertilizer.

Thermochemical conversion of biomass to a gas can be achieved through gasification . The U.S. Department of Energy supports research on biomass gasification for hydrogen production .

Most of the biogas consumed in the United States is produced from anaerobic decomposition and is used for electricity generation. Biogas may qualify as a renewable fuel for electricity generation in state renewable portfolio standards . It also qualifies under the U.S. Renewable Fuel Standard Program as an advanced or cellulosic biofuel and under California’s Low Carbon Fuel Standard as a feedstock for low carbon fuels . On June 21, 2023, the U.S. Environmental Protection Agency (EPA) announced a final rule that established biofuel volume requirements and standards for cellulosic biofuel for 2023–25 as part of the RFS program. The cellulosic biofuel category primarily applies to RNG. RNG is fully interchangeable with fossil-based natural gas and can be injected into natural gas pipelines or used to fuel natural gas vehicles.

Collecting and using biogas from landfills

Landfills for municipal solid waste are a source of biogas. Biogas is produced naturally by anaerobic bacteria in municipal solid waste landfills and is called landfill gas . Landfill gas with a high methane content can be dangerous to people and the environment because methane is flammable. Methane is also a strong greenhouse gas . Biogas contains small amounts of hydrogen sulfide, a noxious and potentially toxic compound when in high concentrations.

Source: Adapted from National Energy Education Project (public domain)

In the United States, regulations under the Clean Air Act require municipal solid waste landfills of a certain size to install and operate a landfill gas collection and control system. Some landfills reduce landfill gas emissions by capturing and burning—or flaring—the landfill gas. Burning the methane in landfill gas produces CO 2 , but CO 2 is not as strong a greenhouse gas as methane. Many landfills remove moisture, siloxane, and sulfur from the biogas to generate electricity and some treat the biogas further to produce RNG.

EIA estimates that in 2022, about 216 billion cubic feet (Bcf) of landfill gas was collected at 334 U.S. landfills. That landfill gas was burned to generate about 8.5 billion kilowatthours (kWh) of electricity, or about 0.2% of total U.S. utility-scale electricity generation in 2022. 1

Biogas from sewage and industrial wastewater treatment

Many municipal sewage treatment plants and manufacturers, such as paper mills, food processors, and breweries, use anaerobic digesters as part of their waste treatment processes. Some sewage treatment plants and industrial facilities collect and use the biogas produced in anaerobic digesters to heat the digesters, which enhances the anaerobic digestion process and destroys pathogens. Some facilities use biogas to generate electricity to use at the facility or to sell to the electric power grid. EIA estimates that in 2022, 102 waste treatment facilities in the United States produced about 1 billion (972 million) kWh of electricity.

Anaerobic digesters at the Lincoln, Nebraska wastewater-treatment facility

Source: Lincoln, Nebraska government (copyrighted)

An anaerobic digester at a dairy farm

Source: Michigan State University (copyrighted)

Using biogas from animal waste

Some dairy farms and livestock operations use anaerobic digesters to produce biogas from manure and from used bedding material from their barns. Some livestock farmers cover their manure holding ponds (also called manure lagoons ) to capture the biogas that forms in the lagoons. The methane in the biogas can be burned to heat water and buildings and to generate electricity for the farm in diesel-engine generators. EIA estimates that in 2022, 23 dairies and livestock operations with anaerobic digesters in the United States produced about 0.1 billion (121 million) kWh of electricity from biogas.

1 Utility-scale power plants have at least 1 megawatt (1,000 kilowatts) of electricity generation capacity.

Last updated: December 15, 2023, with data available in the EIA-923 survey database for 2022.

• Electric Power Annual data on landfill gas for electricity: Tables 5.6.A–F
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What Is Biogas? Is It Sustainable?

Discover the benefits and consequences of this renewable fuel.

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• Renewable Energy
• Fossil Fuels

How Is Biogas Made?

• Environmental Benefits
• Consequences

Is Biogas Carbon Neutral?

• Frequently Asked Questions

Biogas is fuel gas made from biomass, either by decomposition or chemical processes. Biogas is 50% to 75% methane , while the remaining percentage is carbon dioxide and traces of other compounds.

When it is reduced to nearly pure methane, biomethane can replace fossil fuel-based " natural gas " for electricity generation, transportation, heating, and home cooking. In the United States, nearly all biogas is produced for use in electricity generation.

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Natural organic matter such as crop residues, animal manure , as well as forestry and wood processing waste, are broken down in biodigesters, which use anaerobic (oxygen-free) digestion to produce biogas. Biogas can also come from recovering methane from landfills and from wastewater treatment plant sludge.

What Is Anaerobic Digestion?

Anaerobic digestion uses microorganisms to break down biological material without oxygen. It is a multi-step process: Bacteria turn organic material into soluble derivatives, which are broken down by other bacteria into simple sugars, amino acids, and fatty acids. Then, they are converted further into acetic acid, ammonia, hydrogen, carbon dioxide, and other compounds, then finally into methane, carbon dioxide, and other trace compounds.

Most biogas in the United States comes from municipal solid waste (landfills), while in Europe it comes from crop waste and animal manure, and in China primarily from manure.

Environmental Benefits of Biogas

Biogas can have environmental benefits, some more obvious than others. For example, unlike wind and solar energy, biogas is able to be used on demand when other renewable resources are unavailable. Developing renewable biofuels as a backup energy supply allows for the development of carbon-free wind and solar energy while eliminating, or at least reducing, the need for non-renewable fossil fuel energy.

Reducing Landfill Emissions

Landfills contribute up to 20% of anthropogenic methane emissions and, in the United States, are the third leading source of methane emissions. Capturing landfill gas and converting it to biogas is part of many countries' efforts to reduce their greenhouse gas (GHG) emissions. But transforming those sources of landfill gas into biogas before they reach the landfill is a more efficient use of resources and reduces other pollution problems as well.

For example, turning wastewater sludge into biogas takes less energy than converting it into compost. Converting animal manure and crop wastes to biogas prevents runoff of these potential pollutants into waterways. Burning biogas from pre-treated leaves also produces fewer GHG emissions than composting them. The trade-off is a decrease in the availability of an important organic fertilizer.

Dinodia Photo / Getty Images

Roughly 30% to 40% of food is wasted and ends up in landfills, making food waste the single largest category of landfill material. Giving wasted food an economic value decreases its presence in landfills and reduces municipal costs and methane emissions from rotting food.

Combatting Deforestation

Biogas can help reduce deforestation in areas of the world where firewood is the main source of home cooking and heating fuel. Half of all forest wood production worldwide is for fuelwood, one-third of which is harvested unsustainably. In sub-Saharan Africa, an estimated 70% of deforestation is due to fuelwood collection.

Switching to biogas can reduce fuelwood consumption by nearly half. As a result, it also reduces by up to half the amount of time spent collecting firewood, a task most frequently performed by women and school-age children, reducing the labor burden on the former and increasing the educational opportunities of the latter.

Cleaner Than Fossil Fuels

Compared to diesel, using biomethane as a vehicle fuel reduces GHG emissions and particulate matter by up to 75%. Compared to burning fossil methane for electricity generation, biomethane reduces GHG emissions by 62% to 80%. Coupling a biogas-burning power plant with carbon-capture technology can reduce GHG emissions even further (up to 87%), though carbon capture and storage technologies have yet to reach commercial viability.

Consequences of Burning Biogas

While it can be renewable and have environmental benefits, burning biogas still emits greenhouse gases and other pollutants into the atmosphere.

Renewable, but How Sustainable?

Transportation and storage of both biomass and biogas result in emissions of CO 2 and particulate matter. As with fossil fuel methane, fugitive emissions are a concern at biogas plants. In both cases, methane emissions result when biogas is incompletely burned. When the storage of anaerobic digestion tanks goes uncovered, the GHG emissions benefits of biogas over fossil methane disappear.

The carbon cycle involved in using agricultural products to produce biogas may be renewable. However, considering the entire life cycle of biogas production—including agricultural emissions, transportation, refining, and combustion—the use of biogas as a fuel source is by no means carbon neutral.

Air Pollutants

Biogas combustion can also lead to the emission of sulfur dioxide, carbon monoxide, volatile organic compounds (VOCs), and, most significantly, nitrous oxides, where biogas emissions are higher than those of natural gas combustion. Trace components of other pollutants at biogas plants, including carcinogens such as arsenic, have been found at higher levels than at natural gas plants as well.

Manure-to-biogas and other biogas projects based on industrial animal agriculture are often cited adjacent to low-income communities or communities of color, exposing them to pollutants and discharging nitrates into the local groundwater. These instances make biogas production an environmental justice concern.

Land Use Changes

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As the market for biogas grows, so too do negative land use changes, where crops are grown specifically for biogas production. In Italy and Germany, biogas production expanded significantly in the first decade of the 21st century, leading to higher food and land rent prices, as land clearing for intensive agricultural production increased.

In Indonesia, the use of palm oil effluent increases the profitability of the palm oil industry, encouraging the spread of oil palm plantations into one of the world’s most important old-growth forests.

Biogas is touted as "renewable," "sustainable," and "carbon-neutral," mostly by its promoters. But calling biogas carbon neutral doesn't look at the whole life cycle of the product.

The carbon that is released when biogas is burned comes from plants and other sources that originally pulled that carbon from the atmosphere, making the mere burning of the material itself carbon-neutral. But looking at the entire life cycle of biogas, including its production and transportation, as well as all the carbon embedded in the equipment used in those processes, makes the biogas industry a net contributor of carbon to the atmosphere.

No, it is not different. Methane is CH 4 , whatever its source. But neither biogas nor natural gas is pure methane. Each contains other gaseous compounds.

No. Once it's burned, it can't be recycled, and any unburned methane released when turning biogas into energy remains a potent greenhouse gas.

There is currently less financial incentive to grow crops specifically for biogas, as the market is less predictable than traditional food crops. Farmers are able to grow and sell their main food crops, then sell their waste products to supplement that income.

Li, Yin, et al. “ Composition and Toxicity of Biogas Produced from Different Feedstocks in California .” Environmental Science & Technology , vol. 53, no. 19, 2019, pp. 11569–11579., doi: 10.1021/acs.est.9b03003

" Biogas explained: Landfill gas and biogas ." U.S. Energy Information Administration .

" Biosolids Technology Fact Sheet Multi-Stage Anaerobic Digestion ." United States Environmental Protection Agency .

" An introduction to biogas and biomethane ." International Energy Agency .

Arasto, A., et al. “ Bioenergy's role in balancing the electricity grid and providing storage options: An EU perspective .” IEA Bioenergy : Task 41P6 Vol. 2017 No. 1.

Singh, Chander Kumar, Anand Kumar, and Soumendu Shekhar Roy. “ Estimating Potential Methane Emission from Municipal Solid Waste and a Site Suitability Analysis of Existing Landfills in Delhi, India .” Technologies 5:4 (2017), 62–78. doi: 10.3390/technologies5040062.

" Greenhouse Gas Inventory Data Explorer. " United States Environmental Protection Agency .

Morsink-Georgali, Phoebe-Zoe, et al. “ Compost versus biogas treatment of sewage sludge dilemma assessment using life cycle analysis .” Journal of Cleaner Production 350 (2022), 131490. doi: 10.1016/j.jclepro.2022.131490

de Jesús Vargas-Soplín, Andrés, et al. “ The potential for biogas production from autumn tree leaves to supply energy and reduce greenhouse gas emissions – A case study from the city of Berlin .” Resources, Conservation & Recycling 187 (2022), 106598. doi: 10.1016/j.resconrec.2022.106598

" Food Loss and Waste ." U.S. Food and Drug Administration .

Hagman, Linda, et al. “ The role of biogas solutions in sustainable biorefineries .” Journal of Cleaner Production 172 (2018), 3982–3989. doi: 10.1016/j.jclepro.2017.03.180

Bailia, Robert, et al. “ The carbon footprint of traditional woodfuels .” Nature Climate Change 5 (2015), 266–272. doi: 10.1038/NCLIMATE2491

Subedi, Madhu, et al. “ Can biogas digesters help to reduce deforestation in Africa? ” Biomass and Bioenergy 70 (2014), 87–98. doi: 10.1016/j.biombioe.2014.02.029.

Desta, Getnet Alemu, et al. “ Biogas technology in fuelwood saving and carbon emission reduction in southern Ethiopia .” Heliyon 6 (2020) e04791. doi: 10.1016/j.heliyon.2020.e04791

Meeks, Robyn, Katherine R. E. Sims, and Hope Thompson. “ Waste Not: Can Household Biogas Deliver Sustainable Development? ” Environmental & Resource Economics 72:3 (2019), 763–794. doi: 10.1007/s10640-018-0224-1.

Pérez-Camacho, María Natividad, Robin Curry, and Tomas Cromie. “ Life cycle environmental impacts of biogas production and utilisation substituting for grid electricity, natural gas grid and transport fuels .” Waste Management 95 (2019) 90–101. doi: 10.1016/j.wasman.2019.05.045

Feiz, Roozbeh, et al. “ The biogas yield, climate impact, energy balance, nutrient recovery, and resource cost of biogas production from household food waste—A comparison of multiple cases from Sweden .” Journal of Cleaner Production 378 (2022) 134536. doi: 10.1016/j.jclepro.2022.134536

Esquivel-Patiño, Gerardo G., and Fabricio Nàpoles-Rivera. “ Environmental and energetic analysis of coupling a biogas combined cycle power plant with carbon capture, organic Rankine cycles and CO 2 utilization processes .” Journal of Environmental Management 300 (2021) 113746. doi: 10.1016/j.jenvman.2021.113746

Buratti, C., M. Barbanera, and F. Fantozzi. “ Assessment of GHG emissions of biomethane from energy cereal crops in Umbria, Italy .” Applied Energy 108 (2013), 128–136. doi: 10.1016/j.apenergy.2013.03.011

Paolini, Valerio, et al. “ Environmental impact of biogas: A short review of current knowledge .” Journal of Environmental Science and Health 53:10 (2018), 899–906. doi: 10.1080/10934529.2018.1459076

Li, Yin, et al. “ Composition and Toxicity of Biogas Produced from Different Feedstocks in California .” Environmental Science & Technology 53 (2019), 11569–115769. doi: 10.1021/acs.est.9b03003

Gittelson, Phoebe, et al. “ The False Promises of Biogas: Why Biogas Is an Environmental Justice Issue .” Environmental Justice (2021), doi: 10.1089/env.2021.0025

Britz, Wolfgang, and Ruth Delzeit. “ The impact of German biogas production on European and global agricultural markets, land use and the environment .” Energy Policy 62 (2013), 1268–1275. doi: 10.1016/j.enpol.2013.06.123

Bartoli, A., et al. “ The impact of different energy policy options on feedstock price and land demand for maize silage: The case of biogas in Lombardy .” Energy Policy 96 (2016), 351–363. doi: 10.1016/j.enpol.2016.06.018

Sodri, Ahyahudin, and Fentinur Evida Septriana. “ Biogas Power Generation from Palm Oil Mill Effluent (POME): Techno-Economic and Environmental Impact Evaluation .” Energies 15 (2022), 7265. doi: 10.3390/en15197265

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How Biogas Systems Work

Organic material.

Organic materials are the "input" or "feedstock" for a biogas system. Some organic materials will digest more readily than others.

As material is deposited in the landfill and covered, anaerobic microbes consume organic material and burb out biogas, which is vacuumed out through buried, perforated pipes.

Add organic material to these engineered tanks, which are usually stirred and heated to about 100º F, and the same anaerobic microbes produce biogas, which is captured in the digester's air-tight, flexible roof.

Biogas consists mostly of methane and carbon dioxide, plus water vapor, and other trace compounds (e.g., siloxanes)

DIGESTED MATERIAL (DIGESTATE) In addition to biogas, digesters produce solid and liquid digestate, containing valuable nutrients (nitrogen, phosphorus & potassium) and organic carbon. RENEWABLE NATURAL GAS

Biogas processed to gas pipeline quality is often called biomethane, renewable natural gas, or RNG.

American Biogas Council

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