Law 13,576 of 2017, which instituted RenovaBio, defines a bonus of up to 20% on the environmental energy efficiency score for the producer who proves to have a negative carbon footprint in the biofuel production life cycle. This can mean up to 20% more decarbonization credits issued and more revenue generated for the producer.

Currently, the most efficient ethanol producers have a carbon intensity of the order of 16 grams of carbon dioxide equivalent per megajoule. How, then, to make this number negative and receive the bonus on the issuance of decarbonization credits? Incremental gains through improvements in production processes in the agricultural and industrial areas are unlikely to lead to a negative carbon footprint. A promising path is the introduction of technology for capturing and storing geological carbon in bioenergetic production, known by the acronym BECCS.

While Carbon Capture and Storage mitigates carbon dioxide emissions in industries dependent on fossil energies, such as coal or gas thermoelectric plants and steel mills, the Bioenergy model with Carbon Capture and Storage promotes the effective removal of carbon dioxide carbon from the atmosphere. Therefore, it is one of the core technologies for achieving the carbon neutrality goals to which the world's major economies are committing.

The International Panel on Climate Change estimates that it is necessary to implement Bioenergy projects with Carbon Capture and Storage to remove 328 billion tons of carbon between 2020 and 2100, more than will be possible with the planting of new forest areas, estimated by 252 billion tons of carbon dioxide in the same period.

Briefly, with Carbon Capture and Storage technology, the carbon dioxide resulting from the burning of fossil fuels, which would be emitted into the atmosphere, is captured and injected back into the sedimentary rocks from which it came, which naturally house the reserves of carbon. oil, natural gas or coal. It has been used for over 40 years in the oil industry to inject carbon dioxide obtained from natural gas purification into producing fields and increase oil recovery. The process retains some of the carbon dioxide in the reservoir rock, but its main objective is not to reduce carbon dioxide emissions, but to increase oil production.

The first Carbon Capture and Storage project exclusively for the reduction of carbon dioxide emissions was developed in the Sleipner gas field by the Norwegian state oil company Equinor and became operational in 1996. Of the nearly 30 Carbon Capture and Storage projects Carbon operating on a commercial scale in the world, at the end of 2021, more than 70% were from advanced oil recovery, and the rest were aimed at reducing emissions.

Among them is a Bioenergy with Carbon Capture and Storage project, implemented at ADM's corn ethanol plant in Decatur , Illinois. With the ability to inject 1 million tons of carbon dioxide per year since 2017, it was developed with financial support from the US government to demonstrate the technology's feasibility on a commercial scale.

Carbon Capture and Storage technology has three main components: capture, transport and storage. The capture is done in stationary sources of carbon dioxide, where it is separated, at a high cost, from the other gases emitted in the burning of fossil fuels. The captured carbon dioxide is transported by pipelines or, eventually, ships (in the case of maritime projects), to a geologically suitable injection point in a sedimentary basin. The technology of construction and operation of pipelines and ships is the same used in the transport of natural gas, largely dominated by the oil industry.

Sedimentary basins cover most of all continents. In Brazil, there are more than 6 million square kilometers of sedimentary basins, of which 4.9 million square kilometers are on land and the rest on the continental shelf. The geological storage of carbon requires two essential conditions: the existence of porous rocks filled with salt water (saline aquifers); and, immediately above them, a layer of sealing impermeable rock.

Due to the need to compress the carbon dioxide to reduce its volume and increase its density, the injection is carried out at more than 800 meters of depth, where the pressure in the rock pores is sufficient to maintain the pressure of the injected carbon dioxide. Carbon dioxide injected into the saline aquifer laterally displaces water from the formation and tends to rise with time because of its lower density. This upward trajectory is impeded by the sealant rock, forming, then, a carbon dioxide plume around the injection well, which is completely contained in the reservoir rock and tends to stabilize over time, including the mineralization of part of its content by chemical interactions with the formation water.

The great competitive advantage of the ethanol industry is that the carbon dioxide formed in the fermentation vats has a purity of around 98%. Thus, it is only necessary to compress and dehydrate for subsequent transport to a geologically favorable location for injection. Considering the low cost of capture and the fact that most of the sugarcane ethanol plants are located in the Paraná sedimentary basin, there seems to be the perfect combination for the implementation of Bioenergy projects with Carbon Capture and Storage in this area.

There is no major technological challenge in the process of compressing and dehydrating carbon dioxide, which uses technologies largely dominated by the oil industry. On the other hand, geological studies need to define the locations and depths where conditions are suitable for the safe and permanent injection of carbon dioxide. It is important to emphasize that the projects must have an effective monitoring system to demonstrate that the injected carbon dioxide will not migrate from the reservoir rock to the surface, which would invalidate the obtaining of carbon credits.

The generation of revenue for the remuneration of the project will depend on the price conditions of the carbon market, whether regulated (RenovaBio) or voluntary. In the United States, the federal government created an incentive of 50 dollars per ton of carbon, which was recently increased to 85 dollars, which led to the emergence of several projects, especially in the ethanol industry. In Brazil, the incentive is a 20% subsidy on the issuance of decarbonization credits.

A serious problem is the lack of a legal framework that defines relevant aspects for Carbon Capture and Storage projects, such as the right of access and exclusive use of porous space (reservoir rock) and the right to issue carbon credits, among others. other points. There is a draft bill generated within the scope of the Fuel for the Future Program, being approved by the Ministry of Mines and Energy for later submission to Congress, and, in the Senate, a regulation proposal presented in May by Senator Jean Paul Prates (Partido dos Workers), who is on the Infrastructure Commission.

The implementation of Bioenergy with Carbon Capture and Storage in the ethanol industry in Brazil requires the coordination of efforts of the sector with the Federal Government, so that we have, as soon as possible, a Carbon Capture and Storage policy in the country and its infralegal regulation, unlocking the implementation of projects and the creation of a new market for services, as well as generating additional revenue for producers and decisively contributing to the fight against climate change by removing carbon from the atmosphere.