Making it simple: How Biogas works

December 6, 2023



Carbon neutrality
Grégoire Guirauden

Grégoire Guirauden

Chief Operations Officer

Do you know what biogas is and how it's produced?

Because it's a complex topic, only the experts seem to really understand the biogas process.

Biogas is a key pillar of the EU decarbonization strategy as it has an increasingly important role in replacing natural gas. Its production is both natural and sustainable, offering a cleaner alternative to traditional fossil fuels but also helps manage organic waste efficiently.

The world needs to be aware of its power. Our challenge in this article is to make it easily and quickly understandable. So let’s get started.

Understanding The Basics of Biogas

Biogas is about turning waste into wealth

Biogas is a versatile and sustainable energy source created through the decomposition of organic matter in the absence of oxygen. It is generated through the anaerobic digestion of organic materials such as agricultural residues, food waste, sewage, and animal manure - resulting in the release of methane and carbon dioxide. The process captures these potent greenhouse gases, to be reused rather than sending them out again into the atmosphere.

Biogas is a Green Alternative to Fossil Fuels

Biogas stands out as a green alternative to traditional fossil fuels. Unlike finite resources, biogas production relies on a constant and renewable supply of organic waste. This not only addresses the energy crisis but also helps mitigate the environmental impact associated with the extraction and combustion of fossil fuels.

A biogas production site in North of France

Why Biogas is an environmental hero

Biogas has one main benefit: Greenhouse Gas Reduction

Biogas boasts an 80% smaller carbon footprint in comparison to natural gas.

One of the most significant environmental benefits of biogas is its role in reducing greenhouse gas emissions. By capturing methane - a potent greenhouse gas - during the anaerobic digestion process, biogas systems prevent its release into the atmosphere, and use it to replace natural gas instead.

The key mechanism involves the anaerobic digestion of organic materials, such as agricultural residues, animal manure, and organic waste. During this process, (see details below) methane, a potent greenhouse gas, is captured and then utilized as a renewable energy source instead of being released into the atmosphere (which is what happens with natural gas for instance).

Biogas can also enable Waste Management Marvel

Biogas systems offer a sustainable solution to the burgeoning issue of organic waste. From agricultural residues to food scraps, these systems convert waste into energy, simultaneously addressing waste disposal challenges and minimizing the environmental impact of landfills.

Biogas also can also make Healthier Soils

The solid residue left after digestion, known as digestate, serves as a nutrient-rich fertilizer, providing essential nutrients like nitrogen, phosphorus, and potassium back to the soil. It also promotes better aeration and water retention and balances PH balance. This improvement in soil structure is crucial for the health of plants, as it allows roots to penetrate easily, facilitates nutrient absorption, and reduces the risk of soil erosion. Therefore, by using digestate as a natural fertilizer, farmers can reduce their reliance on chemical fertilizers.

Biogas can enhance energy sovereignty

By promoting local energy production, biogas diminishes reliance on externally sourced energy.  Unlike centralized power plants, biogas systems can be implemented at or near the point of organic waste generation, such as farms or wastewater treatment plants, reducing the need for extensive energy-transportation infrastructure - therefore also strongly decreasing the need to import fossil fuels.

An approach that not only promotes off-grid energy access in remote areas but contributes to reducing imports and addressing countries’ trade deficits (including France's for example) in several ways. By bolstering domestic energy production and utilizing local resources, biogas helps limit energy imports and reduce the trade deficit by mitigating expenses associated with energy imports.

Biogas can strengthen the resilience of agricultural jobs

Biogas benefits farmers by turning agricultural waste into a reliable on-site energy source, reducing energy costs, and providing nutrient-rich fertilizers for improved soil health. This sustainable solution not only fosters environmental stewardship but also creates additional and diversified income opportunities through the sale of excess energy. Besides, by-products provide an alternative and often more cost-effective source of energy contributing to the overall resilience and economic sustainability of farming operations.

Biogas site are always located close to the feedstock access, and so often managed by group of farmers.

Biogas has awide range of usages & at different scales

Biogas finds applications across various sectors and can be implemented on various scales - from small-scale community digesters to larger industrial facilities. A decentralization of energy production contributes to local power generation, reducing reliance on centralized energy sources and therefore promoting energy independence.

Know that it has the same usage but releases 90% less carbon emissions than natural gas.

Did you know biogas is used to :

  • Produce heat and power systems: biogas can be burned directly for heating purposes. This is commonly used for space heating in buildings, heating water for industrial processes, or providing heat for greenhouses and agricultural applications. Industries with significant organic waste streams, such as food processing or breweries, can benefit from biogas systems both for waste management and energy needs.
  • Generate vehicle fuel (bioGNL): Biogas can be processed and upgraded to biomethane, a purified form of methane. Biomethane can then be used as a compressed natural gas (CNG) or liquefied natural gas (LNG) for vehicles. A great alternative to traditional fossil fuels for transportation.
  • Generate electricity: biogas can be used to generate electricity through the combustion process. It powers generators or engines that convert the energy from biogas into electrical power. This application is particularly useful for both grid-connected and off-grid systems.
  • Cogenerated or Combine Heat and Power (CHP): Cogeneration involves the simultaneous production of electricity and useful heat from the same energy source. Biogas CHP systems are designed to maximize efficiency by capturing and utilizing the heat generated during electricity production for various industrial processes or district heating.
  • Cook & heat : in many households, especially in rural areas, biogas is used for cooking and domestic heating. Biogas stoves and burners are employed to replace traditional solid fuel sources, reducing indoor air pollution and improving health conditions.

So, technically, how does Biogas work?

Biogas is a gaseous fuel composed primarily of methane, (CH4) which typically constitutes 50-70% of the gas, along with carbon dioxide (CO2) and trace amounts of other gases such as hydrogen sulfide (H2S). The methane content is crucial, as it determines the energy content and usability of the biogas.

Let’s go through the creation process, step by step.

STEP 1: Feedstock Collection

Biogas production begins with the collection of organic materials, known as feedstock. This can include a variety of organic waste such as agricultural residues, food waste, sewage sludge, manure, and other biomass sources. The choice of feedstock depends on availability, local conditions, and the desired output of the biogas system.

Important note: in France the rate of dedicated cultivation is capped at 15%. Dedicated cultivation involves growing crops exclusively for bioenergy purposes. In the USA, for instance, 40% of corn production is utilized for biofuel and has a primary goal of creating biogas rather than managing waste. Notably, Riverse's certification ensures that the dedicated cultivation remains below 3% even after three years of activity.

STEP 2: Pre-Treatment (Optional)

In some cases, feedstock may undergo pre-treatment to optimize the anaerobic digestion process. Pre-treatment methods can include shredding, grinding, or other mechanical processes to increase the surface area of the organic material, making it more accessible to microorganisms.

STEP 3: Loading into the Biogas Digester

The prepared feedstock is loaded into a sealed container called a digester. The digester is designed to create an oxygen-free (anaerobic) environment, allowing anaerobic microorganisms to thrive and break down the organic matter.

STEP 4: Anaerobic Digestion

Within the digester, anaerobic microorganisms, predominantly bacteria, start breaking down complex organic compounds into simpler molecules through a series of biological reactions. These microorganisms work in different stages, converting carbohydrates, fats, and proteins into organic acids, and ultimately into biogas. This digestion process is facilitated by bacteria that thrive in oxygen-deprived conditions.

STEP 5: Biogas Storage and Collection

The generated biogas is stored within the digester. To collect and utilize the biogas, the digester is equipped with a gas collection system. This system captures the biogas and directs it to storage tanks or directly to applications such as electricity generation, heating, or cooking.

To do so, first comes purification: this means separating the different types of gases. Then comes the distribution of each gas for a specific use. The focus is on separating biomethane, which is highly useful and can be injected into the regular gas network (the one that heats your water heater and powers your stove).

Meanwhile, carbon dioxide (CO2), which is generally less valuable, is often released (although it would have been emitted anyway) or occasionally collected for use in the food industry (think sparkling water bubbles) or in agricultural greenhouses (to speed up tomato growth for example).

STEP 6: Digestate Production

As a byproduct of anaerobic digestion, a nutrient-rich material called digestate is produced. Digestate is the solid residue remaining after the biogas has been extracted. This material is a valuable organic fertilizer that can be used in agriculture to replenish nutrients in the soil and complete the cycle of sustainability.

Biogas plants are the new symbols of the decarbonization landscape.

Biogas' industry needs support

As technology advances, ongoing research and innovation continue to show the benefits as well as improve the efficiency of biogas systems. Governments and organizations worldwide are recognizing the potential of biogas in achieving sustainability goals.

However, biogas represents only 0,9% of the gas consumption in France whilst its objective is 7% in 2030 and 20% in 2050. Despite supportive policies and incentives put in place, the industry still strongly requires support for several reasons.

Natural gas remains cheaper:

The production of natural gas involves extracting it from underground reservoirs, which tends to be a relatively inexpensive process. Additionally, natural gas benefits from economies of scale, with large-scale production and well-established extraction and distribution infrastructure.

In contrast, biogas production involves processing organic waste, which can incur additional costs, and often operates on a smaller scale, lacking the economies of scale that characterize natural gas production. Also, the infrastructure for natural gas distribution is already well-established, making it more cost-effective to transport and distribute compared to decentralized biogas production, which may face higher transportation and distribution costs. Things are slowly changing but sadly today, paying for natural gas even with the carbon tax still remains cheaper than purchasing biogas.

A high capital investment:

As you can imagine, setting up biogas infrastructure, such as anaerobic digesters and associated equipment, involves a significant upfront capital investment. Many farmers, small businesses, or communities find it challenging to secure the necessary funds to initiate biogas projects.

Once biogas systems are established, ongoing maintenance and operation are crucial for their success. Especially in the past years with electricity inflation, costs have increased considerably to keep the production going. Financial support, grants, or subsidies can help overcome this barrier and encourage the adoption of biogas technology.

A lack of education & awareness:

Many potential users may not be aware of the benefits of biogas or may lack the knowledge to implement and maintain biogas systems. Support for educational programs and awareness campaigns can help inform communities, farmers, and businesses about the advantages of biogas and how to adopt it effectively.

We can now say you understand more about biogas. So yes it’s not that sexy. But it’s truly efficient. As a product and for the planet.

In the quest for sustainable energy solutions, biogas emerges as a shining star, offering a clean, renewable, and locally sourced alternative. Its ability to address environmental challenges, provide economic opportunities, and contribute to a decentralized energy landscape positions biogas as a key player in the transition toward a greener and more sustainable future! So let’s share about this sector and support it- to make the world a better place.

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