The phrase “everything can be used from sugarcane” is no longer a jargon to become a reality available to all mills in the sector. Previously treated as waste, vinasse, filter cake, straw and bagasse, today, are actually by-products used as fertilizers and inputs for other industries, such as ethanol (second generation), cellulose, plastics and biogas.

Among these uses, the production of biogas has gained prominence over the last few years and it has become common to see news of large companies that seek to make their products and processes greener, replacing the use of fossil fuels and derivatives with biogas or biomethane. Automobile industries, such as Volkswagen and Scania, fertilizers, such as Yara, food, such as Liane, and animal supplementation, such as the Yes yeast factory, even fossil fuels, such as Petrobras, are examples. pioneers in this quest for a carbon-free market.

Biogas is the mixture of gases obtained by the biological degradation of organic matter in the absence of oxygen. In a simplified way, we can say that everything that naturally decomposes can generate biogas, from the organic fraction of household waste to industrial by-products. As it is an extremely adapted natural process, it occurs in the most diverse conditions. Of course, the industrial application of this process requires much more than leaving the residue to degrade in one place, but we will talk about that later.

This mixture is mainly composed of methane and carbon dioxide, usually saturated in water and having other contaminants (mainly Hydrogen Sulfate). Therefore, biogas must first be purified to remove water and Hydrogen Sulfate, and then be used directly in boilers (low efficiency and energy use) or in motor generators . After a process of removing carbon dioxide, known as upgrading, the biogas becomes biomethane, a gas that is similar, substitutes and interchangeable with natural gas, which can replace fossil fuels such as gasoline, liquefied petroleum gas and diesel.

At this point, it is already possible to talk about the many possibilities of arrangements for biogas. As it is storable and generates dispatchable energy, it can be combined with intermittent energies, such as solar and wind, making their use even more feasible. In the case of fuels, since biomethane is an excellent substitute for diesel, in a double with ethanol, it would make a fleet of light and heavy vehicles carbon neutral.

And speaking of replacing diesel, the time is also ideal for biogas. There are already tractors and trucks of different specifications commercially available, aligning the power and performance of diesel vehicles with the economy and zero carbon footprint of biomethane. Another positive aspect of biogas is the possibility of decentralized and inland production, making green natural gas available in regions far from the coast and promoting the industrial development of these regions. This inland potential is known as the caipira pre-salt.

However, it is not just its main product, biogas, that biodigestion is revolutionary. Its co-product, the digestate , a material that has undergone the anaerobic biodigestion process , has many positive characteristics. The biodigested compost has the same nitrogen, phosphorus and potassium contents as the original residue, that is, there are no losses in its fertilizing power;

What is consumed in the biodigestion process to generate biogas is compostable organic matter, which would be degraded and lost in the field anyway. The difference here is that when degradation occurs in the field, this process first takes nutrients from the soil, delaying plant development. On the contrary, when digestate is applied, it immediately begins to supply nutrients to the crop and can accelerate growth. Digestate has even greater potential to add nitrogen to the soil and promote its recovery and carbon fixation.

Amid this atmosphere of excitement, a brief pause for reflection is necessary. We need to look to the past and learn from its lessons. It is not the first time that biogas has appeared on the scene: both in the 1980s (at the time of the oil crisis and the project by the Instituto de Assistência Técnica e Extensão Rural do Paraná, which installed more than 3,000 small biodigestors in the country) and in the beginning in the 2000s (due to the carbon credit market), we have seen projects emerge in this area, and few follow through. What would be different this time? We highlight a few points here.

First, the general picture of the need to reduce dependence on the fossil matrix, both in terms of economics and availability (see gas crisis in Europe) and in terms of the environment. Renewable energy sources have never been more sought after and needed. Second, the favorable regulatory environment, which clearly defined the characteristics of biomethane and its equivalence and interchangeability with natural gas, in addition to the new regulatory framework for natural gas in Brazil, which creates a dynamic market, with more investment and infrastructure.

Last but not least, the existence of technologies for the production of biogas already adapted and proven for the by-products of sugarcane, cake, vinasse and straw. And this is where the choice of producer makes all the difference. As mentioned before, because it is a natural process, biogas can be produced in any condition, as any fruit left aside will ferment. However, just as industrial fermentation is very different from a forgotten fruit, so is biodigestion at scale.

To guarantee the achievement of the sector's biogas production potential, guarantee supply contracts and make projects viable, technology is needed. We need processes that have monitoring and control of industrial variables, such as quality and quantity of waste feed, temperature, pressure, agitation and removal of biogas from biodigesters, so that we are not simply passengers in a process that works or not regardless of our intervention.

If the present is good, the near future is even better for biogas. Its similarity to natural gas allows us to use biogas as a raw material for the chemical industry, replacing hydrocarbons and derivatives with green and renewable alternatives. Hydrogen, jet fuel, methanol, Dimethyl Ether and many other products can be produced from biogas.

Much more than residues, filter cake, straw and vinasse are raw materials for the generation of biogas, and much more than biogas, a new world of green products and hydrocarbon derivatives that only the scale of the sugarcane industry in Brazil and available industrial biogas production technology are capable of achieving.