Discovered in 1766 by Cavendish as a combustible gas formed in the reaction between metals and acids and baptized as “the former of water” by Lavoisier in 1783, hydrogen is the simplest and most abundant chemical element, representing 75% of the mass of the Universe, but constitutes less than 1% of the mass of our planet Earth, almost always associated with other elements, such as with oxygen in water.

Hydrogen has different properties from other gases, which can represent advantages, such as a high calorific value, or difficulties, such as low density (less than 10% of the density of air), high flame speed and, curiously, being one of the few gases that heats up when expanding, imposing its cooling by safely supplying tanks that must withstand very high pressures, on the order of 900 atmospheres.

Although the use of hydrogen for energy purposes has long been suggested by visionaries such as Jules Verne, its high cost, compared to fossil fuels, has been an obstacle to its diffusion in these applications. However, nowadays, industrial applications of hydrogen are important, especially in petroleum refining and ammonia production, with a global demand of about 75 million tons per year, produced basically from natural gas and petroleum, with the significant emission of fossil carbon dioxide and, therefore, increasing the greenhouse effect in the atmosphere. It is, therefore, an undesirable hydrogen.

In the context of the current global energy transition, with the replacement of fossil energy sources with renewable energy sources, meeting the objectives of decarbonizing energy matrices, increasing energy security and economic rationality, the hydrogen that everyone seeks is green hydrogen, that is, hydrogen produced from renewable energy, replacing “dirty” hydrogen in uses as a raw material and opening new markets in the energy sector, as fuel in furnaces and boilers in industries, in energy storage systems (increasingly necessary due to the expansion of intermittent generation of wind and solar plants) and in the transport sector, where diesel, gasoline and kerosene still largely dominate. In this direction, several agencies project a major expansion of renewable hydrogen production, requiring investments of over 200 billion dollars, to meet an expected demand of around 550 million tons in 2050. The highlighted figure indicates the projects currently underway, especially in Europe and Asia.

Processes for the production of renewable hydrogen: The most promising technological routes for the production of renewable hydrogen are:

a) from electricity, through the process of electrolysis, in which water is separated into its components. It is the most mature and widely adopted process in projects currently being implemented, in which electricity must be produced from renewable sources;
b) from biomass, by three alternatives: (1) the reform of biomethane , the main component of biogas, (2) the reform of ethanol, similar and technologically mature endothermic processes, in which with adequate catalysts and water, the energy of these biofuels allows maintaining reactors (reformers) at temperatures between 650 and 900 degrees centigrade, and producing streams with hydrogen, which can be purified at high levels, and (3) in low-cost solid biomass gasification processes, producing gases with levels of lower hydrogens, but which can also be purified. These last processes are under development, with promising results, however, without having yet demonstrated their economic viability.

Preliminarily, comparing the costs of producing hydrogen in electrolysers and through ethanol reforming, without considering the investments in equipment and installations (certainly higher in electrolysis) and taking into account only the costs of inputs (electricity and ethanol), it is possible to obtain the parity curve indicated in the highlighted figure. In summary, ethanol is competitive in the production of hydrogen, considering the current values of electric energy, which, only at very low values, is the best option.

Initiatives in Brazil to produce hydrogen involving biomass: For Brazil, with a good endowment of natural resources and mastery of bioenergetic technologies, biomass is configured as an alternative with effective potential in the hydrogen economy and which has been the object of such innovative initiatives as interesting, presented below.

Hydrogen from ethanol reform. The company Hytron, from Sumaré, São Paulo, founded in 2003 as a by-product of the Universidade Estadual de Campinas, was incorporated, in 2020, by the NEA Neuman and Esser group, from Aachen, Germany, reinforcing its performance in the integration of systems with a focus on hydrogen. Among its products, with its own technology, Hytron offers a line of hydrogen production systems by ethanol reform, with a capacity of up to 750 kilograms of hydrogen per day, consuming 7.65 liters of ethanol and 2.35 kilowatt hours per kilogram. of hydrogen produced.     

Electric vehicles with hydrogen fuel cells generated by onboard ethanol reform. Since 2016, the automaker Nissan has been developing, with Brazilian and Japanese entities, electric vehicles in which electricity is generated in solid oxide fuel cells, fed with hydrogen produced in the vehicle itself, through the catalytic reform of ethanol. The tests showed the technical feasibility, with the prototype mounted on a van making about 30 kilometers per liter of ethanol. The project is still under development, aiming to improve performance and reduce the volume occupied by the reformer. Other automakers showed interest in this solution for the electrification of their models.

Green ammonia production using hydrogen produced by reforming biomethane generated in the biodigestion of ethanol vinasse. In 2021, the companies Raízen and Yara established a consortium for the production of green ammonia, using hydrogen produced from biomethane resulting from vinasse biogas. An interesting feature of this project is that the biomethane will be produced in Piracicaba, injected into the Gasbol pipeline and transported to Cubatão, on the coast of São Paulo, where it will be used to produce hydrogen and, from there, ammonia with a low carbon footprint.

Just as an exercise, considering that 4.85 cubic meters of biomethane produce 1 kilogram of hydrogen, which, in turn, combined with nitrogen, gives rise to 5.67 kilograms of ammonia, the Brazilian Biogas Association's recent estimate of a production of 2.2 million cubic meters per day of biomethane in Brazil, in 2027, could mean around 940 thousand tons of green ammonia per year, 40% above the apparent national consumption of fertilizing ammonia in 2017.

Although these notes are dedicated to hydrogen from biomass, it is worth mentioning that other routes connecting renewable hydrogen and biomass are advancing. As a good example, the Ômega Green project, being implemented by BSBios Paraguay, with investments of around one billion dollars, will use hydrogen produced with hydroelectricity, abundant in the neighboring country, and Paraguayan vegetable oils to manufacture green diesel and renewable aeronautical biofuel, in a volume equivalent to more than one billion liters per year, largely to expose tar. Brazilian companies are starting projects in this direction.

In conclusion
Hydrogen is not and should not be seen as a new energy source. Hydrogen is, in fact, an energy vector, perhaps a promising technology for energy transport, capable of carrying this “capacity to transform” that we call energy. It has unique properties and, when produced with a low carbon footprint, could be a relevant component of the global energy transition, expanding the space for renewable and sustainable energies.

There are technical and economic challenges to overcome, but the strong interest of some countries and companies in its development is creating favorable conditions for the effective creation of a new energy industry, focused on the production and use of hydrogen.

In this world that is coming, bioenergy finds new and relevant opportunities, as we seek to signal in these notes. Borrowing some calculations from Daniel Lopes, from NEA Hytron , who considered the various energy vectors that sugarcane is capable of providing, first and second generation ethanol, biogas and bioelectricity , each ton of cane is capable of producing 17, 8 kilograms of hydrogen.

So, just speculating, the 654 million tons of cane that Brazil harvested in the 2020-2021 harvest could, in theory, produce 11.6 million tons of hydrogen, whose production by electrolysis would consume 568 Terawatts hour, 14% above national consumption. of electric energy observed in 2022. In view of this, is there room for biomass in the hydrogen economy?