BIOFUELS: BACK TO THE PAST TO SAVE THE FUTURE

Dr. Alex M. A. Campos

Dra. Kelly Ribeiro

Prof. Dr. Paulo Santos Assis

The use of biomass is the oldest method of supplying energy to humanity, in 1850 biomass represented 85% of the world's energy consumption. Before that, it was practically the only form of energy used by man, in addition to wind power for navigation and domesticated animals in agriculture. With the Industrial Revolution that began with the use of steam engines at the end of the 18th century, the importance of coal, which was small, used mainly for residential heating, increased to 15% in 1850 and quickly grew to 50% by the end of the 19th century, from then, oil and gas became dominant (GOLDEMBERG, 2009).

The development of modern society is still mostly based on the consumption of fossil fuels, and so then, is associated with environmental issues related to climate change. The transport sector is responsible for a large quota, 25% of world energy consumption (BARNéS, 2016).

An interesting alternative to reduces greenhouse gas emissions is the use of biofuels. Brazil has an immense potential for the production of biofuels based on a more conscious and sustainable agriculture, supporting regional initiatives that are based on social and environmental benefits, such as family farming. In 2019, according to the Ministry of Mines and Energy, biodiesel and bioethanol were capable to mitigate 69.6 MtCO2 in the country′s transport sector.

One of the main challenges in the production of biofuels is the diversification of raw material sources. Another bottleneck is the technical-scientific improvement of technologies for processing more complex raw materials, such as agribusiness residues. In addition to the positive environmental effects of using biomass as a fuel source, there are several economic and social aspects to consider. Regarding the environmental issue, it can be said that greenhouse gases are emitted during the burning of these materials, but the amount is similar to that produced by the natural decomposition process. In addition, in the case of plant biomass, during its growth, carbon dioxide is consumed by photosynthesis, which can generate a positive balance when analyzing the emission of these gases (Campos, 2018).

Macauba oil has been attracting great attention from researchers and industrial sectors focused on the production of biofuel, especially biodiesel, green diesel and aviation biokerosene. The palm, native from tropical and subtropical regions, is a perennial tree capable to sequester 50% more CO2 than an annual plantation, what increase its sustainability (VIEIRA et al., 2020; COLOMBO et al., 2016). Forthermore, it is believed that macauba can help to reduce the emission of polluting gases by civil aviation by up to 80% (SILVA, 2016; ALMG, 2019).

However, for each kilogram of oil extracted, there is approximately 4 kg of residues with energy potential. Processing the residues mean add value to the entire production chain, reducing costs, opening the possibility of trading carbon credits, and provide an adequate destination for what could become en environmental liability.

In this context, one of the studies in sustentabiulty alternatives from Federal University of Ouro Preto post graduated in Materials Engineering program? is about the energy recovery of macauba’s lignocellulosic residues through thermal liquefaction. This is a thermochemical treatment in the presence of a solvent, at moderate temperatures and high pressure. It promotes the depolymerization and breakdown of complex bioplymers into smaller and easier to use compounds, providing energy density (ARAúJO, 2020). The main product, the biocrude, can be converted into biofuel, and the biochar, also obtained, can be used in the energy sector or even return to the macauba′s production chain, as it has interesting properties to be applied to the soil.

Another hand of the research group is add value of agribusines waste, converting this in fuels for differents sectors. The amount of residues after harvest can reach 50% of production by weight in some cases, such as coffee and soybeans. Considering only agricultural production in Brazil, the Brazilian Association of Biomass and Renewable Energy Industries -ABIB showed that in the 2010 harvest, around 600 million tons of waste were generated in agricultural activity.

One of the sectors that the renewable energy group has been studying is the steel industry. The steel industry is responsible for about 10% of all CO2 emitted into the atmosphere (IEA, 2020) and the absolute majority of these emissions are due to heavy consumption of coal. Campos, 2018 showed that it is possible to replace part of the coal used in the steelmaking processes, and only in the blast furnace is it possible to reduce emissions by 40% with a partial replacement of the coal used. Carvalho, 2021 used sawdust to replace 2% of coal in coke production. It was shown that in addition to the financial gain, it is possible to avoid the emission of 128 thousand tons of CO2 in the atmosphere annually.

Obviously the use of biomass in the steel industry is not so trivial. In addition to the logistical aspects, there are technological aspects that must be developed for the best use of this biofuel. From a logistical point of view, the availability of biomass is usually far from steel plants, in addition to biomass having a low density, requiring some type of compaction or carbon concentration to optimize and enable transport.

From a technological point of view, it is necessary to develop technologies for the conversion of biomass because in raw form it presents difficulties to use, such as low density and high volatile content, in addition to the low fixed carbon content. In this sense, the group's recent research has been based on the development of the production of a "Biocoal", where the biomass, waste from various agricultural products, undergo a pyrolysis process and transform into a charcoal with a higher fixed carbon content and more dense, which facilitates transport and use in processes such as the blast furnace and cokemaking.

The fact is that biomass is returning to the world scene as the short-term alternative, mainly in developing countries, viable for reducing CO2 emissions into the atmosphere and we have to be prepared for this use. The research group on renewable energies at the Federal University of Ouro Preto has doctoral, master's and undergraduate researchers in addition to partner companies to develop different applications of biofuels. Biomass has returned to be a fuel of the future and we will be ready to use it in the best possible way in all the processes that are necessary.

REFERENCES

GOLDEMBERG, José. Biomassa e energia.?Quím. Nova,?S?o Paulo ,? v. 32,?n. 3,?p. 582-587,? ? 2009 .

ARAúJO, M.F.R.S. Produ??o e caracteriza??o de biocombustíveis a partir da liquefa??o térmica de baga?o de cana-de-a?úcar. 2020. 153f. Tese (Doutorado em Química) -Universidade Federal de Minas Gerais, Belo Horizonte, 2020.

ALMG (2019). Disponível em: https://ubrabio.com.br/2019/08/28/projeto-macauba-seria-saida-sustentavel-para-economia-de-mg/ . Acessado em: 10/08/2020.

SILVA, L. N. Síntese e Caracteriza??o de Biocombustíveis Drop-in a partir dos óleos da Macaúba. 2016. 163f. Tese (Doutorado em Química) - Universidade Federal de Minas Gerais, Belo Horizonte, 2016.

VIEIRA (2020). PORTAL MACAúBA. Disponível em: https://www.portalmacauba.com.br/2020/05/macauba-e-uma-palmeira-aproveitada.html . Acessado em: 10/09/2020.

COLOMBO A.A., BERTON L.H.C., FILHO J.A.A., CARVALHO C.R.L., HERNANDEZ B.G.D., SIQUEIRA W.J. Macaúba: múltipla e sustentável. O Agron?mico. Boletim Técnico Informativo do Instituto Agron?mico. (2016).

BARNéS, M.C. Liquefaction of lignocellulose – Biocrude, char and chemistry of liqefaction. 2016. 230f. Dissertation to degree of doctor – University of Twente – Netherlands, 2016.

CAMPOS, A.M.A., ASSIS, P.S., NOVACK, K.M.?Aspectos Econ?micos E Ambientais Do Uso De Biomassas Na Siderurgia, p. 21-32. In:?48° Seminário de Redu??o de Minérios e Matérias-primas, S?o Paulo, 2018.

CARVALHO, L.A.L., CAMPOS, A.M.A., ASSIS, P.S. Quality evaluation of metallurgical coke produced with sawdust and different mixture of coal. REM, Int. Eng. J.,?Ouro Preto,?v. 74,?n. 2,?p. 219-223, 2021.?

ABIB – Associa??o Brasileira De Indústrias Da Biomassa. Inventário residual Brasil 2011. Disponível em: <https://pt.calameo.com/accounts/200968 >. Acesso em: 23/02/2021

IEA- International Energy agency. Global crude steel production by process route and scenario, 2019-2050.2020a. Disponível em: <https://www.iea.org/data-and-statistics/charts/global-crude-steel-production-by-process-route-and-scenario-2019-2050 >. Acesso em 26/02/2021.