When we talk about renewable gas, we often think of new energy technologies. However, there is already a real alternative that makes use of something as everyday as waste: biogas and its upgraded version, biomethane.
In this article, we answer the most common questions: what is biogas, how biogas is produced, what biogas is used for and why it is increasingly considered one of the main alternatives to natural gas in the energy transition.
What biogas and biomethane are
Biogas is a renewable gas generated from organic waste, such as agricultural, livestock or urban waste. Its main components are methane (CH₄) and carbon dioxide (CO₂).
When this biogas undergoes a refining process to remove CO₂ and other impurities, biomethane is obtained. In other words, if you are wondering what is biomethane, the easiest way to understand it is as an “upgraded” version of biogas, with characteristics that are practically identical to natural gas.
That is why both biogas and biomethane are considered renewable gases: they make it possible to generate energy from waste and reduce dependence on fossil fuels.
How biogas is produced from waste
If you want to know how biogas is produced, the process is more natural than it may seem.
It is obtained through a process called anaerobic digestion, in which microorganisms break down organic matter in the absence of oxygen. This process takes place in facilities called biodigesters.
During decomposition, two main products are generated:
- A gas (biogas), which can be used as a source of energy
- A solid residue (digestate), which can be used as fertiliser
This model turns waste into resources, placing biogas production at the heart of the circular economy.
What biomethane is and why it can replace natural gas
To fully understand what is biomethane, we need to go one step beyond biogas.
Biomethane is obtained after an upgrading process, in which impurities are removed from biogas until it reaches a methane content of more than 96%. The result is a gas that is practically identical to natural gas.
This has a key advantage: it can be used in existing infrastructure (gas networks, boilers, etc.) without requiring major changes.
That is why biomethane is one of the few renewable solutions that can be directly integrated into the existing energy system.
What biogas and biomethane are used for
When someone searches for what is biogas used for, the answer includes several key energy applications.
Use of biogas for heat and self-consumption
Biogas is usually used close to where it is produced, especially in agricultural or industrial settings.
The main uses of biogas include:
- Generating heat for agricultural or industrial processes
- Producing electricity through cogeneration systems
- Reducing external energy consumption on farms or production sites
In fact, using biogas electricity generation is one of the most common applications today.
Biomethane in the gas network and heating
Biomethane opens up many more possibilities.
Because it is compatible with the gas network, it can:
- Be injected directly into existing infrastructure
- Be used for domestic heating
- Partially replace natural gas
This makes it a real option among the main alternatives to natural gas, especially in sectors where electrification is not easy.
Biogas and biomethane in Spain: current situation
Spain has great potential to develop biogas, although it is still behind other European countries.
Currently:
- There are more than one hundred biogas plants
- Production remains limited compared to its potential
- Countries such as Germany and France are much further ahead
Even so, the context is favourable: Spain has abundant agricultural and livestock waste, as well as a gas infrastructure that is already prepared to integrate biomethane.
Opportunities and challenges for renewable gas in Spain
The development of biogas in Spain offers major opportunities, but also important challenges.
Opportunities
- Using organic waste to generate energy
- Reducing dependence on fossil fuels
- Promoting the circular economy in rural areas
- Integrating easily into the existing gas network
Challenges
- Lack of clear and stable regulation
- Need for incentives to promote projects
- Administrative complexity in developing plants
- Competition with other renewable energies
Advantages of biogas and biomethane
- They make it possible to generate energy from waste
- They reduce emissions compared to fossil fuels
- They make use of existing infrastructure
- They contribute to the circular economy
- They are a manageable solution, as they do not depend on weather conditions like other renewables
Disadvantages and challenges of biogas
- Higher cost than natural gas in some cases
- Dependence on the availability of waste
- Need for investment in plants and logistics
- Regulatory development still evolving
The role of biogas in the circular economy
Biogas does not only produce energy: it also solves a key problem, waste management.
By transforming organic waste into energy and fertilisers, it closes the resource cycle and reduces environmental impact. That is why it is a key part of the circular economy model, especially in rural areas.
Frequently asked questions about biogas and biomethane
What is the difference between biogas and biomethane?
Biogas is the gas obtained directly from waste, while biomethane is the result of purifying that biogas until it becomes equivalent to natural gas.
Can biogas be used at home?
Directly, this is not usually the case. However, biomethane can reach homes through the gas network.
Is biogas polluting?
The answer is that, although its use generates CO₂ emissions, its impact is much lower than that of fossil fuels. This is because the carbon emitted is part of a recent biological cycle, not fossil carbon accumulated over millions of years.
In addition, capturing methane from waste prevents it from being released directly into the atmosphere, where it would have a much greater climate impact.
Can it replace natural gas?
Yes, especially biomethane, as it is fully compatible with current infrastructure.
Its main advantage is clear: it can be used with the existing infrastructure, without having to completely transform the energy system.
In a transition scenario, where not everything can be electrified immediately, renewable gas plays a key role as a complementary solution.
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