Biogenic gas. What do you mean?

Biogenic gas. What do you mean?

Biogas as an energy source is becoming more and more popular, but what is biogas and how does it differ from natural gas? The difference is that natural gas is a fossil fuel, while biogenic gas is renewable.

Natural gas was formed millions of years ago, at the age of the dinosaurs, like oil or coal. The accumulation of plankton as well as animal and plant rests on the seabed, buried by layers of soil, caused it to be produced in anaerobic conditions, that is, without oxygen.

Biological bacteria decomposed the organic matter and the gases generated bubbled upwards, and where there was an impermeable layer, they accumulated, giving birth to gas pockets or reservoirs. It is therefore a finite resource; once it is exhausted, there will be no more to supply human energy demands.

Natural gas consists mainly of methane, ethane and carbon dioxide, although it usually has other components or impurities, so the energy is obtained by combustion, compared to other fossil fuels it is more efficient and cleaner in terms of emissions, although it depends on the impurities.


Biogenic gas is also produced by the decomposition of organic matter under the action of bacteria, in the absence of oxygen, which is why it is also called Biogenic Natural Gas, but in this case in a tank with controlled conditions of temperature and pressure.

But in biogenic gas, the organic matter used comes from by-products of farms, crops or industries, so it is a renewable energy. The composition of biogenic gas is similar, but with fewer impurities, as the quality is improved by upgrading, which is explained in this blog post.

Moreover, natural gas is thousands of kilometres away, but biogenic gas can be produced in small tanks for self-supply, e.g. on a farm, or on a large scale in a sewage treatment plant, and existing natural gas pipelines can be used.

It may seem to be all advantages, but this is not the case, which is why CARTIF organised the first meeting of the Community of Practice within the Horizon Europe CRONUS project on 20 March 2024.

The Communities of Practice consist of the grouping of different actors in the biogas sector, such as universities, research centres, producers or distributors, among others, and act as spokespersons for the sector for both citizens and administrations, assessing the strengths and weaknesses, facilities and barriers to the use of biogas in order to make responsible use throughout the value chain.

At this first meeting, three main challenges were addressed:

  1. Raw materials
  2. Technology
  3. Regulations: Logistical, Productive, Social

In the first challenge, the issue of raw materials was addressed. At present, there are no problems in finding them, but there are problems in obtaining supplies, the question is: is this a logistical or quantity limit? In terms of accessibility, it is not as accessible in the mountains as it is on the plateau, and in terms of plant and supplier size.

There is also concern that, in the future, due to the law of supply and demand, both raw materials and transport will reach exorbitant prices. It is necessary to start regulating and organising the market to ensure a supply where the whole value chain benefits.

It is important to consider the methanogenic potential, i.e. how much gas a plant can produce with a given raw material, this determines its viability, therefore the raw materials must meet certain standards and heterogeneity all year round, in order to obtain a constant production, both in quality and quantity.

This leads to the question of the suitability of single or multiple feedstock feeding. In some cases, it is necessary to pre-treat these feedstocks and due to the technical complexity they are not cost-effective, so having flexibility in the use of feedstocks is an advantage.

The most worrying aspect is the injection into the grid. There are problems when it comes to incorporating the gas produced into the existing national distribution network, which in some cases favours the self-consumption of gas, but in others, the waste of this energy source is wasted.

It is a mature technology, but there is still innovation to be done, especially with the bacteria, points of improvement such as new strains are still being discovered, and they make the process and therefore its efficiency is much better known.

In the end, it is an investment, so it is necessary to conscientiously measure the risk and profitability vs. administrative and legal barriers, and although more and more people are opting for it, there would be more if there was a financial push with subsidies, but they would not be the basis of the product.

The second challenge was to know the opinions about the FP5 prototype that is being developed in CARTIF within the CRONUS project. That can be seen in this video.

The expert assistants pointed out that it competes directly with upgrading, so it may not be economically viable on a large scale, but for small plants, it is a good solution, as it does not need to undergo such a large purification process.

On the other hand, it needs a hydrolysis stage, which requires energy, but it is a self-sustainable process, so it is able to be self-sufficient.  Technology must favour profitability, as money is always a constraint, both for development and production.

Its strong point was highlighted, which is that it can valorise and reduce the CO2 generated in the AD, obtaining a higher quality biomethane than through traditional processes, especially because cogeneration is more interesting than gas for sale.

As it is the first meeting only the laboratory prototype could be seen, so they perceived that there could be problems in the scaling in the electrodes, as they have to be larger, and there is no microbial electrolysis cell-assisted anaerobic digestion technology (MEC-AD) on the market, but CARTIF already commented that there are more options to integrate MEC-AD in the digester.

It also raised the possibility of problems with having to restart the plant, after a shutdown, which can be slow and complex, but it is a continuous system so it will not be so slow.

The Community is optimistic about CARTIF’s FP5 prototype and is looking forward to seeing its progress in the next calls for proposals.

This challenge is where there was the greatest participation and unanimity. It seems that the Public Administration is not advancing as fast as biogenic gas is. One barrier is the processing time, which can take up to 3 years for project approval, to which environmental authorisations must be added, and the time dedicated to the plant’s engineering project.

This could be favoured with legislation that favours self-consumption, such as premiums or payments for the generation and sale of energy. It would be interesting to map waste production throughout the country.

In the case of Castilla y León, there is the obligation to become an authorised waste manager and limitations on the maximum distance allowed for the transport of digestate, as in the transport of slurry, which shows that the administration is prepared.

But the definition of waste needs to be revised, in order to revalorise by-products for use in anaerobic digestion and also the resulting digestate as it has many potential uses, such as stripping/scrubbing or crystallisation of struvite, which can even be considered as an environmentally friendly product, as fertiliser.

Raw materials, such as slurry, must be used responsibly due to the contamination of aquifers by nitrates, so the use for biogas generation is a solution for this waste, and the resulting digestate could be revalued as fertiliser or as an ingredient for compost.

The growing demand for biogas highlights the need for the modernisation of farms to increase their income from the sale of waste and reduce energy costs by using biogas.

On the other hand, there is a need for the Administration to update its technicians with specific training, since, when evaluating a project, there is no clarity in the criteria, standards and administrative procedures to be applied, and there are differences between technicians.

In short, more support is needed from the Administration, especially with the private companies that control the distribution networks and establish the technical and economic requirements for connection and injection into the network, resulting in abusive technical and economic conditions. The Community of Practice considers this barrier easy to remove.

There is a lack of dissemination and knowledge, which is why citizens associate it with bad smells, noisy lorry movements and a lack of safety, which is why the Community of Practice is doing a good job of disseminating and raising awareness in society of how biogenic gas works and the technology associated with it.

There are both urban and rural barriers, each with its own complexity, in addition to the fact that each Autonomous Community has its regulations in this regard, so each plant in each area must be approached individually, through conferences, citizen participation, a network of interaction with citizens in other areas that already have this technology in place, but above all with transparency.

The reality is that the development of biogenic gas will contribute to rural repopulation, job creation, as well as energy production and the development of the Circular Economy, which is a pending issue in the 2030 agenda.

More information on the CRONUS Project:

Our wonderful guardians and neighbours!

Our wonderful guardians and neighbours!

People hear a lot about the decline of bees, about the lack of pollinators, but what are pollinators? more importantly, what do they do for us and what do we do for them?

The group of pollinators is very wide, not only honey bees, which belong to one specific family.  In fact, in Spain we have more than 1,000 species of bees from six different families, 75% of bees are solitary and live on the ground and with more than 20,000 species of bees in the world they have evolved and are organised in many different ways.

Other pollinators are birds, mammals and reptiles because plants are very clever – they have been on earth for many millions of years longer than we have! And that results in greater evolution and adaptation. Plants have developed sophisticated methods of attraction to achieve their reproductive purposes because the pollen has to reach its destination! They use everything from lizards to flies and bats, not forgetting air and water, which also help in pollination.

But if there are so many means for pollination, why are pollinators, in particular bees, so important? Well, at least, in this case, size and shape matter! There are all kinds of insects, small, fat, long, with very long tongues, in short, many sizes! Just as there are many shapes and sizes of flowers and pollen grains because plants are very sybaritic.

Plants have evolved in such a way that each one has developed its own system, some of them very exclusive, to avoid pollen from other plants, that is why there are so many smells, to make a first selection of “be my guests!”; and many sizes, some bees have to stick out their proboscis or “tongue” up to 20mm to get to the food; some, like the passionflower, have very large stamen and pistils, and can only be pollinated by large bumblebees; others are complicated, like the snapdragon flower, where the bee has to get inside as if it were a cave; and others are smaller, like daisies, which need a small insect and are therefore pollinated, for example, by small black and yellow striped flies, which are the hoverflies. The sunflower is a large daisy and therefore needs a larger pollinator such as the honey bee. There are thousands of families of bees of different sizes, ranging from 4-5 mm to 30-35 mm (honey bees measure between 15 and 20 mm).

Both flowers, sunflower and daisy, have large yellow or white “petals” around them (which are actually ligule) and a bunch of little yellow flowers in the centre from which the seeds come out (which in sunflowers we call pipas). Next time you pass by a park, pick up a daisy and look closely at the yellow part, they are all little flowers! With their stamens, stigmas and all the parts of a flower that we hardly remember from when we studied them at school!

Cut of solitary bee nest. Source: Luis Óscar Aguado

Colours are another attraction mechanism for pollinators to detect them from far away! With our eyesight, all colours look the same to us, but with their special vision, they see the colours of the flowers differently. In the end, plants have made insects and pollinators evolve as pollen carriers, and in return, they provide delicacies in the form of fruit, seeds, pollen, nectar, etc.  As you can see, there are numerous mechanisms to attract the right pollinator, so if the population of one disappears in a short period of time, the plant cannot adapt and even less reproduce.

Bee laying an egg on a bamboo cane. Source: Maria González

Many pollinators obtain food rewards from plants, but they do not feed exclusively on them like reptiles or birds, but bees do, they depend exclusively on plants for food. Both their larvae and the adult insect feed on floral products such as nectar and pollen. And as we have seen, not all flowers feed all pollinators.

So how can we help pollinators?

We can build them a shelter, depending on the family of bees they have different forms of housing or social grouping. Some build galleries in the ground where they live, so placing a pot in the window is enough; others in holes in logs or pieces of wood, even shells!. So a simple and space-saving way is to put up a hotel for solitary bees. It is very simple, consisting of a bundle of cut bamboo canes or a piece of wood with holes of different diameters between 5-25 mm, with a base, that is, that does not go through the wood and without cracks, as these are possible entrances for parasites and predators. There the bees will lay their eggs, which they will leave with the nectar or pollen collected and cover it up, and after a year the new bees will leave and go and look for another hole. So there is no danger of being stung. Bees don’t live there, they just lay their eggs, they are solitary, they don’t form hives, they don’t form communities, they sleep on flowers and branches.

Solitary bees don’t sting! Well yes, but not like honey bees, I mean, many bees die when they sting you, solitary bees do not form communities, as they do not have to defend it, they are not aggressive, they do not attack, they do not sting, this makes it a good idea to install this type of shelters in schools, children can get close and see how many holes are plugged, and count the bees they have helped.

Also, these bees only collect food for their own food and larvae, so they don’t need to collect so much, others need food to raise all their offspring, and others need food for the whole colony and humans, so if you disturb them with your hand, most of them leave, they don’t want trouble, attacking you costs them their lives, but others are more insistent because they need a lot of food and the closer you are to the hive, like the honey bees, the more aggressive they can become and attack.

Pollinators hotel
Bee hotel with two holes fulfill located in CARTIF. Photo: María González.

This is why there are special regulations for keeping beehives, which are considered a type of livestock farming (beekeeping or honey farming) and have to comply with requirements regarding distances to populations, etc. It even has to respect the distance between them, since, if there is little food, it attacks other pollinators, such as solitary bees, as they are competing for food.

It is also important to have flowers all year round, for them and for us, there are many native plants with different flowering periods so that they have food all year round, in different sizes for bees of all sizes.

How do they help us? The best-known part of the work of pollinators is that of pollination. 80% of plants depend on them, and many of them are responsible for providing us with food. 75% of crops currently need pollination, and this includes the crops needed to feed livestock, so the production of livestock by-products also depends on them.

Pollinators module, module with flowers during all the year located in CARTIF. Source: María González

Pollinators are therefore our allies, and it is thanks to them that a large part of natural and urban plant communities and our food is maintained. Climate change, pesticides, agricultural intensification, the continuous clearing and mowing of parks and fields, including the proliferation of beehives, are causing their population to decline rapidly. Moreover, we still have a lot to learn about them, so it is very necessary to help them consciously and rationally, and not only at the level of experts, but also at the social level, all of us can help their conservation, taking care of pollinators and cultivating more flowers around us, since without flowers there are no pollinators and vice versa.


If you want to know more you can consult the websites of great professionals such as and

Bibliography: Curro Molina & Ignasi Bartomeus. 2019. Guía de campo de las abejas de España. Esditorial Tundra, Castellón. 250pp. 19’5 x 12’5 cm. ISBN 978-84-16702-77-0.

Photos: óscar Aguado and María González.