The debate about biogas has reached Catalonia loaded with mistrust, interests, and simplifications. It is normal for it to generate debate: we are talking about organic waste, livestock manure, industrial plants, transport, energy, and territory. But precisely because the topic is complex, it is advisable to avoid diagnoses that mix everything up and end up turning a waste treatment technology into the scapegoat for all the problems of the livestock model.Biogas is an organic waste treatment technology that allows a part of biogenic carbon (of biological origin) to be transformed into methane, a greenhouse gas much more potent than CO₂ in the short term, to be used energetically or molecularly, and to obtain a digested residue that can have fertilizing use if managed correctly. This process is not only for slurry: there is also municipal organic fraction, pruning and gardening waste, sewage sludge, agri-food waste, agricultural residues, food industry waste, and other organic flows that, in the context of climate emergency, must be treated anaerobically (in the absence of oxygen).This is the first misunderstanding. Presenting biogas plants solely as “energy factories” distorts the debate. Their primary function is environmental: to reduce methane emissions, a greenhouse gas dozens of times more potent than CO₂. Once digested, the waste does not release as much methane, it is a chemically more stable fertilizer, with less risk of pathogens and fewer volatile compounds that cause bad odors. The recovery of gas in the form of energy or molecularly is relevant, but it is a consequence of the valorization of a waste that needs to be treated, just like with wastewater treatment plants or municipal organic waste.Catalonia has a real problem of livestock concentration in certain areas, external dependence on feed, and pressure on soils and aquifers. Not all the impacts of the food and livestock model can be attributed to biogas: imported soy, cereals, mineral fertilizers, maritime transport, or agricultural machinery. These impacts exist and must be reduced. But they are not caused by the biogas plant. They are part of the livestock and food system. This problem must be addressed with livestock planning, territorial limits, herd control, strict compliance with nitrate regulations, and better connection between agriculture and livestock. But this debate is not resolved by rejecting anaerobic digestion outright. It is one thing to discuss what livestock model the territory can support, and another to decide how to best treat the manure and organic waste that are already generated.

Recently, various interventions and reports have been published presenting biogas as a renewable and circular energy source. These are messages that hide the complexity of this technology. To begin with, the projected biogas plants are refineries that produce a non-renewable fuel that needs to be processed. Furthermore, the energy balance of the entire process for biogas production, from cradle to grave, is negative: more energy is consumed than is ultimately produced.The internal operation of the biogas plants themselves can absorb nearly 30% of the energy obtained. To this, approximately an additional 16% must be added for the transport of slurry, manure, and animal waste that feed the plants, as well as the resulting digestate to the farms that will accept it. However, the largest – and often ignored – energy cost is associated with the generation of slurry and manure. These materials are not free; they require a significant energy expenditure in feed, climate control, and farm operations. The meat obtained only recovers approximately 50%-60% of the energy contained in the feed, and the energy invested in producing slurry can be equivalent to 80% of the energy that the biogas plant ultimately generates.And what do these feeds contain? Primarily, soy and cereals. Soy mostly comes from America, transported by ships that consume large quantities of diesel. Both soy and cereals are produced using agricultural machinery – again, diesel – and to make them grow, chemical fertilizers and pesticides are needed. The production of these fertilizers depends on fossil fuels and minerals from mines in the Sahara, Canada, and other distant locations, all of which are finite and non-renewable resources. The expansion of these crops also entails other problems, such as deforestation in the countries where they are produced, contributing directly to climate change.To all this, we must add the industrial inputs that these plants require. The project planned in La Sentiu de Sió (Noguera), the largest currently in Catalonia, would annually require thousands of tons of nitric acid, potassium carbonate, ferric chloride, or methanol, in addition to tens of thousands of tons of water. The associated waste is also considerable: ferrous metals, plastics, and contaminated filters, among others.

"Do you agree that the Moià Town Council should promote the urban planning modification of the land in the Castellnou plan for the expansion of the slaughterhouse and the construction of the biogas plant?" This was the question that residents over the age of 16 in this municipality in the Moianès region were asked to answer this Sunday in a non-binding public consultation. With a 30% turnout, 1,487 residents voted against the projects, 151 in favor, 14 abstained, and 11 cast invalid ballots. The platform "Por un Moià Viu" (For a Living Moià), which called for a "no" vote, believes that "the will of the people is clear" in rejecting the expansion of the slaughterhouse and the biogas plant, and points out that they surpassed the 1,451 votes cast for Ara Moià. The party linked to ERC, which governs with a majority, has not taken all the necessary steps. It is the only way to regularize the industrial park and, therefore, save the companies currently located there, but environmentalists and the opposition disagree and believe there are other options.

In 2024, the Catalan government approved the Catalan biogas strategy 2024-2030 and its action plan, which is part of Catalonia's transition to a new, cleaner, more sustainable, democratic and fair energy model, aiming to achieve climate neutrality by 2050. The goal is to define and consolidate the sector by 2030.

In the context of the energy transition and environmental crisis we have been experiencing for years, the United Nations COP28 Climate Summit held in 2023 agreed to promote the reduction of fossil fuels to combat climate change and transition to renewable energies. Catalonia is committed to biogas and biomethane to reduce emissions, move towards energy independence, and promote a more sustainable circular economy.

After three years of procedures, the urban plan to build a macro biogas plant in Sentiu de Sió (Noguera) has received the green light from the Barcelona Urban Planning Commission. It is the largest facility of its kind in southern Europe—it will process around 500,000 tons annually—and could be the first in a wave of biogas factories in Ponent, as part of the rollout of the Catalan Biogas Strategy 2024-2030. However, both the approval of the urban plan and the possibility of more factories proliferating have sparked outrage among some thirty mayors in the region, who are standing firm against the project and have announced they will challenge it in court. Despite the silence of the Generalitat (Catalan Government), the mayors warn that the factory will not be able to operate solely with local slurry and that, in practice, it is a black hole for the Danish investment fund leading it—Copenhagen Infrastructure Partners—to do business with waste that will come either from Aragon or the province of Barcelona. This waste includes animal remains and slaughterhouse waste, and not just slurry.

ERC is championing the right to decide, but in Moià, where it governs with an absolute majority, it is putting every possible obstacle in the way of its residents voting on whether they want the slaughterhouse expansion and the installation of a biogas plant. On May 21, the municipal government refused to admit the consultation to promote the 200 residents in the town hall square.

The controversial Nova Tracjusa project in Juneda (Garrigues), which aims to gasify urban waste as the main source of heat to dry excess slurry from pig farms, has now passed the final administrative process. After receiving all the environmental and planning authorizations, the City Council has now granted the final construction permit. GAP, the cooperative of 160 livestock farmers in the region, associated with the Griñó Group, can begin executing its project.