United Nations sustainability development goals approached from the side of the biological production of fuels

Abstract

Huge economic and technological leaps have been made since the start of industrial revolution in the 18th century and through developments in the last 70 years. Improvements in the production and quality of goods, increases in food production and advances in medicine have contributed to enhance human life expectancy across the world. The increase in human population, with the trend of people moving from rural zones to cities, the vision of large companies for instant global business and, the development and expansion of terrestrial, maritime and air transportation have led to a highly connected world. The current COVID pandemic has exacerbated the global universe and the ‘internet of things’ has arrived and plans to stay. During the first two decades of the 21st century, it has been estimated that terrestrial transport represents nearly 20% of all carbon emissions, and CO2 emissions linked to aircraft were calculated to be 2% of all human emissions (www.eee.europa.eu; Becken and Mackey, 2017). The continuous increase in CO2 in our atmosphere with current levels of 420 ppm – about 20% higher than 50 years ago, and other greenhouse gases has given rise to a silent pandemic. Some aircraft builders (e.g. Boeing) are planning to fly using 100% sustainable aviation fuels by 2030 and several companies have reported successful testing of biofuel aircraft (www.biofuels-news.com/Feb 2021). Global climate change could devastate our environment if a point of no return is reached, this would result in a shortage of food that leads to massive malnutrition, famine and, eventually end our civilization. Many voices, governmental and non-governmental, are asking for measures to ameliorate first the current situation and then to restore conditions that are compatible with sustainable life. The Kyoto Protocol and the more recently the Paris Climate Agreement call for the use of clean, green and renewable fuels to replace fossil fuels in all transportation areas (United Nations, 2016). The overall goal is to reduce petroleum energy dependence by more than 80% by 2050, a goal which requires multiple approaches – eolic-, thermo-solar, photovoltaic, wave power, bioenergy and others forms of renewable energy. No single means of making energy is sufficient to cover the world’s energy demands (Chen et al., 2017); however, when developed and used concurrently, these approaches may be sufficient to meet current and future demands. These alternative sources of energy can be sourced from sunlight (i.e. photovoltaic and thermosolar), wind, ocean tides, plant biomass and microbes (Hussain et al., 2017). Significant efforts are being made to reduce the Carbon footprint related to transportation and a number of measures are being taken to introduce electric and hybrid cars, hydrogen propelled trucks, trains and other heavy vehicles. However, due to the nature of the different means for transportation (terrestrial, maritime, air), different types of fuels have to be considered. Liquid biofuels for transportation already represent an alternative to replace not only part of the fossil hydrocarbons but also as a means to save carbon emissions and reduce toxic net emissions linked to gasoline and diesel combustion motors. Below, we analyse how developments in bioethanol comply with UN SDGs, and provide suggestions for more clean energy generation. In the late 1980’s Gro Harlem, Norwegian prime Minister and chair of the Commission on Environment and Development, defined Sustainable development as ‘development that meets the needs of the present without compromising the ability of future generations to meet their own needs’ (https://en.unesco.org/themes/what-is-esd). However, it took until 2015 for the adoption of 17 multilateral and international SDGs in the 2030 Agenda for Sustainable Development, which were approved at the UN SDG summit held in New York in the fall of 2015 (https://sustainabledevelopment.un.org; United Nations, 2015). Although measures to reach SDGs are not compulsory for governments, it is true that some Governments are making efforts to design policies to reach them, unfortunately the rate of adoption of said measures is not sufficient such that the desired objectives will be reached by 2030 (Bexel and Jonsson, 2016; Barbier and Burgess, 2017). The current concept of Sustainable Development encompasses three interconnected loops: economic development, social inclusion and environmental sustainability (United Nations, 2015). The SDGs aim to ameliorate global warming, the most obvious damage of which are those from natural disasters caused by unusual atmospheric phenomena for example intensive rains and floods and extreme dry spells. The less obvious of which are unexpected biological events such as plagues, diseases and virus expansion like the current COVID pandemic (Brüssow, 2020, 2021). Biofuels are produced from biological materials, most often oils, cereal grains, sugarcane or biomass derived from plants or wastes, and they represent an alternative to fossil fuels that offers a number of social, economic, environmental and technical benefits (Koçar and Civaş, 2013; Voegele, 2013; Ramos et al., 2016; Valdivia et al., 2016; Ramos and Duque, 2019). The main drivers behind biofuels are: (i) energy supply security and reduction in fossil oil use (SDG 7: Clean energy); (ii) support of rural areas through technology development and new jobs based on technology (SDG 2, 8 and 9), (iii) mitigation of global GHG emission and reduction of particulate materials that are toxic for humans, animals and plants (SDG 7). Therefore, biofuels can contribute towards the responsible use of energies and the replacement of a fraction of fossil fuels by one of the available green renewable sources (https:www.eca.europa.eu). Achievement of SDGs requires holistic action, however, they must be deconstructed and analysed at the sector level to define how industrial activities can be modified to favour the achievement of SDGs. Biofuels are considered renewable fuels because they are derived from plant materials that are made through photosynthesis and CO2 fixation; processes which in principle reduce net emissions of GHG. However, just because a biofuel derives from CO2, fixation is not sufficient to declare it a viable alternative. The rules established by Hill et al. (2006) for ‘a biofuel to be a viable fossil-fuel alternative should be considered; namely, a viable biofuel must provide a net energy gain, have environmental benefits, be economically competitive and be produced in large amounts without reducing food supplies’ (Hill et al., 2006). Therefore, for a specific biofuel, the total carbon sequestered by plants must compensate for all the emissions linked to its production and manufacturing (Hill et al., 2006). Furthermore, the full life cycle has to be considered so that in term of emissions its production should count direct and indirect emissions derived from changes in land use, the amount of carbon sequestered and the amount of greenhouse gases emitted (Crutzen et al., 2008; Mosier et al., 2009, 2014). In general, achieving carbon neutrality for biofuels requires high plant yields and low emissions. The so-called first generation ethanol produced from cereals was the subject of controversy because the UN considered that as a consequence of derivation of cereals to ethanol the cereal prices for human consumption increased. In addition, fears arose because the use of agricultural land for biofuel production could endanger food production, these issues have been and are part of the ‘food versus fuel’ debate. Nonetheless, the field of bioethanol production in particular and biofuels in general, is an exceptionally dynamic and exciting arena and this industry can contribute positively to a number of the SDGs. Together they can help to reduce poverty (SDG 1); reduce fossil oil dependency for energy and because combustion of biofuels is cleaner than fossil fuels lead to a reduction in net toxic emission is achieved (SDG 7); through the use of agricultural residues and municipal solid wastes support a circular economy (SDG 2 and 3); facilitate land restoration and promote the use of land and marginal lands to grow energy crops, which leads to the creation of high-qualify and stable rural jobs (SDG 8 and 13); they can also promote industrial development and specialized job creation (SDG 9). In the case of ethanol, the world production of bioethanol is estimated (gallons per year) to be about 15 billion in the United States, 6 billion in Brazil and about 3 billion in Europe; which is equivalent to the replacement of about 750 million barrels of petroleum every year. Below we analyse bioethanol, the largest fermentative process for a chemical commodity in the context of UN SDGs. SDG1: ‘reduce poverty’. The petroleum market is highly volatile due to limited reserves and the distribution of these reserves in countries with unstable political situations. Reducing dependency of oil and gas supply from a few countries by self-produced renewable energies will help to recover world equilibria and create new resources for countries adopting renewable energy approaches, which in turn will help to reduce poverty (Gielen et al., 2019). At present, advances in the area of biofuels take place in more developed countries, particularly the United States, however, industrial plants located in other countries which are capable of generating energy are feasible – governments need to support their stable operation and educate the population to advance these solutions. Guaranteed energy supply promotes advances in the primary sector and will support industrial development, which in turn contributes to reduce poverty. SDG 2: ‘Zero hunger’. Goal 2 aims to end hunger and all forms of malnutrition by 2030. It also commits to universal access to safe, nutritious and sufficient food all times of the year. This requires sustainable food production systems and resilient agricultural practices, equal access to land, technology and markets and international cooperation on investments in infrastructure and technology to boost agricultural productivity (htpps./www.theexplorer.no/goals/zero-hunger/. www.jordantimes.com). Bioethanol, produced from corn grain (or other cereals) in the United States, Europe and Asia, and sugar cane (Brazil), became controversial because the UN concluded that food prices increased due to biofuel production. Although currently the corn used to produce biofuels are non-edible varieties, the land used for grain production for biofuel competes for land for grain for human use, and hence we have to take it as a negative factor because the so-called first-generation (1G) bioethanol is mainly made from food crops grown on arable land (Mohr and Raman, 2013). 1G ethanol producers have implemented a series of technological advances to reduce environmental impact, that is through harvest of CO2 for medical or industrial uses, corn oil recovery for human consumption and the use of the resulting solid residues – known as dry distillers’ grain (DDG) – that is used as animal feed, because it is rich not only in fibre but also in protein and vitamins from the yeasts used to ferment sugars in the ethanol production process. SDG 7: Energy is crucial for achieving almost all of the Sustainable Development Goals, from its role in the eradication of poverty through advancements in health, education, water supply and industrialization, to combat climate change (htpps./www.theexplorer.no/goals/affordable-and-clean-energy/). Bioethanol is the most relevant biologically produced commodity. Almost all of the ethanol used in the world for pharma, solvent industries and fuels is produced through biological fermentation. The so-called 1G bioethanol fuel is produced worldwide, although the main producers are Brazil and the United States. Ethanol is produced through the fermentation of sugars derived mainly from corn grain and sugarcane, as well as from sugar beet, wheat grain (or other cereal grains), molasses and various other plants, including fruit and fruit waste. In the case of grain, the first step of biofuel production is the hydrolysis of starch using amylases. This process produces simple sugars – mainly glucose – which are then fermented to ethanol using microorganisms such as yeasts or bacteria (e.g. Zymomonas). In the United States, ethanol production rates are in the range of 14–15 billion gallons per year at corn dry mills and this technology is quite mature and industrial ethanol plants are usually profitable in the United States. In Brazil, around 5 billion gallons of ethanol are produced annually and the leftover waste (i.e. bagasse) is often burnt in the mills to generate extra energy. SDG 9: ‘Industry, innovation, and infrastructure, which aims to build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation’. Infrastructure provides the basic physical systems and structures essential to the operation of a society or enterprise. Industrialization drives economic growth, creates job opportunities and thereby reduces income poverty. Innovation advances the technological capabilities of industrial sectors and prompts the development of new skills (htpps./www.theexplorer.no/goals/industry-innovation-and-infrastructure/; www.unstats.un.org). Innovation and Development in the field of bioethanol started with an attempt to address the food versus fuel controversy that forced the bioethanol industry to search for new feedstock. Biomass was considered the most immediate source for bioethanol, and likely other chemicals (Duque et al., 2018; Pandey and Prakash, 2018). This gave rise to the concept of cellulosic ethanol or 2G bioethanol that can be made from corn stover, sugarcane straw, wheat straw and other agricultural wastes, as well as the organic fraction of municipal solid waste (MSW) (Schwartz, 2010). Because 2G ethanol technology is based on byproducts of other crops (i.e. food crops on arable land), it opens significant opportunities to the whole manufacturing chain, including farmers, the ethanol industry, new biotechnology companies, project developers and investors. However, this sector is not mature and still requires significant industrial improvements before it can become a consolidated process. Obviously, an added-value of second-generation biofuels is the avoidance of competition for food producing land and the reduced need to use additional water or fertilizers. To place the biofuel contribution to SDG9 in context, we should consider that the production of 2G bioethanol involves three major actions: (i) the physicochemical pre-treatment of the biomass that destroys plant structure and makes biopolymers available (ii) the enzymatic breakdown of cellulose and hemicellulose into constituent sugars to provide abundant glucose (~ 70%) and xylose (~23%); and (iii) fermentation of these C6 and C5 sugars using specialized yeasts (Taherzadeh and Karimi, 2007; Alvarez et al., 2016). Several physico-chemical pre-treatments efficient in deconstruction of plant materials are in place and no major developments are pending except in the area of biomass handling. The main source of enzymatic cocktails for cellulose and hemicellulose are enzymes secreted by fungi. Relevant developments in the area of 2G technology are still needed (Sharma et al., 2020). The degradation of cellulose and hemicellulose requires a number of enzymes that work cooperatively to breakdown cellulose and hemicellulose through the action of endocellulases followed by a number of exo-cellulases that release oligosaccharides that through the action of and enzymatic cocktails by or the release of 80% of the sugars in and et al., 2016). The area of enzymatic hydrolysis has achieved with but the represent to of the operation and with the are higher which in turn creates and et al., 2016). It is that in technology is will likely from the use of enzymes and from new that the from the cocktails in one or more are available to more and enzymes for of the improvements will the generation of through or The enzymatic take place in an environment and at high These two are relevant as they reduce by source of relevant enzymes are from extreme and the development of design of stable et al., and (Duque et al., 2018). Although using cocktails made of and such as those that in may be feasible to reduce of the some of these are the biofuel sector can promote the development of industries to produce the of sugars from corn stover, sugarcane straw and other agricultural residues are rich in C6 and C5 but because most not ferment C5 sugars and a number of yeasts have been that are capable of these sugars and 2008; and 2017). These can more than of and more than of xylose into ethanol, and when with fermentation of the – an achievement that how this technology has advances in fermentation are at some enzymes on the which can enhance the amount of sugars available for fermentation or These improvements in the sector can be and new the production of biomass for 2G technology can be considered a relevant can replace gasoline in combustion has been produced at an industrial level through the process of fermentation by different of The fermentation yields a of and ethanol but production can be increased to represent to 80% of the et al., support that is more profitable than bioethanol and that the to ethanol plants to can be in years on the plant production number of are to (i.e. from agricultural waste and that a second-generation industry is feasible et al., 2021). The of municipal solid waste (MSW) into bioethanol is et al. estimated that of the organic fraction of municipal solid waste to fuels may save to of all of the fuel used in the transport sector in the United States. of bioethanol from a million of per year would provide billion gallons of ethanol with a of million In addition, the of the organic fraction into ethanol will save emission of greenhouse gases to the SDG climate action to combat climate change and its Climate change the single to development, and its and most action to combat climate change and its is to the successful of SDGs In to reduce oil dependence and save the United to gasoline and ethanol years ago, the known as gasoline a ethanol with This can be used in without and it has been established that it reduces particulate emissions, and and emissions – the most toxic in but in the levels of emissions increase SDG on and promote sustainable use of terrestrial combat and and land degradation and forms of life on land requires efforts to restore and promote the and sustainable use of terrestrial and other Goal 15 on lands and reducing natural and The use of marginal for energy production has been analysed by et al. the process requires of plants to lands and the of that conditions and requires not only of the energy per and the biofuel to be produced but should also take into less obvious that plants will 20% of the CO2 to which in part will be as a carbon This carbon will be a source of to and will help restoration of and Ramos and 2021). The of represents a relevant of Carbon and carbon may with of its The of marginal for energy production will enhance available and in the may for Energy plants are grown for biofuel production, but the crops with (Koçar and Civaş, 2013; et al., 2013). in the United States, the most energy plants are and et al., in Europe crops are sugar and is the main energy grown in Brazil with sugar being fermented and burnt in cycle the is grown in new to create more and energy plants that can be grown in marginal the held by at present only about of the total energy used from and in the transport sector only about of the world’s fuel for transport is of biofuel (Sharma et al., 2020). are opportunities to increase the use of renewable In to reduce dependency on several international and governments are to use biofuels to supply of their transportation energy by 2050, although current to use hydrogen to may change this should consider that the of biofuels their use as transportation and should be given to the economic and environmental benefits of the the of chemicals for production of of every and 2008; et al., and et al., et al., 2013; et al., 2013; et al., Ramos and Duque, 2019). The replacement of fossil fuels by 1G and 2G ethanol reduces greenhouse gas emissions, and the need for In it with UN SDGs that the use of renewable energy Furthermore, bioethanol is linked to agricultural crops and in this it promotes the creation of rural the of 2G ethanol and requires to help create mature ethanol production processes and which are for the production and adoption of The In the 2G process a the process this the the of the sugars and other The most immediate use of this is to it to generate However, the is in the a that can be to produce new and start a new et al., 2014). number of enzymes including and others are being in an to release as or modified to create new and 2017). The to should if this the of the 2G bioethanol industry will in of the residues to At which 2G technology will then contribute to 3 in the of in was by in was by

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