Assessment of waste types for pyrolysis and transesterification for conversion into biofuels

Assessment of waste types for pyrolysis and transesterification for conversion into biofuels

Abstract

            Ideally, this paper seeks to have a comprehensive review of the issue of production of biofuels. It starts off by explaining what triggered off the research; the reduced levels of fossil deposits which resulted into considering alternative fuels. The paper then looks at various articles that talk about production of biofuel, pyrolysis and esterification. The purpose of doing this is to understand the various concepts applied in the production of biofuel and how essential they are when it comes to developing cheaper alternatives to be used in production of biofuels. The paper also looks into the definition of some terms that have been used in the paper and this is to enhance one's understanding of what is being talked about. The paper then discusses some of the findings that have been deduced from the various literature that have been reviewed. Finally, the paper ends with a conclusion which represents the summary of everything that has been discussed in the paper.  

Chapter 1: Introduction

In recent times there is an increasing concern about the levels of fossil deposits and hence there is a shift towards alternative methods of generating biofuels. However, a key concern is how such alternative methods can be made cost-effective and hence reliable, and also be sustainable. Some identified techniques for converting biofuels included pyrolysis and transesterification. One of the alternatives identified to be produced from feed stocks that are starch-based, sugar based and lignocellulose materials using the fermentation process is bioethanol (Branco, Serafim and Xavier, 2018). The use of lignocellulosic materials for the production bioethanol is the main point of concern in this paper since the sugar-based and starch-based materials are easily found from staple food. There are various steps involved in the production of lignocellulosic materials and they include pre-treatment, fermentation, hydrolysis and purification. This paper is going to look at a detailed analysis of the recent progresses that have been made with regards to use of lignocellulosic materials in the production of bioethanol. That aside, the study will equally evaluate the use of pyrolysis and transesterification that is used in making bioethanol from biomass.  

Aims of the Study

1.      To assess the cost effectiveness of commercializing ethanol

2.      To study the functionality and application of pyrolysis and transesterification production of bioethanol from the conversion of biomass

Objectives of the study

Look into various literature talking about the transesterification process as well as production of biofuel to get insight on alternative, cost effective, production methods used in production of biofuels. This will help assess the cost effectiveness of commercializing ethanol. Also, it is going to help in understanding the application of the pyrolysis and transesterification process and how they could be used to make the production of biofuel easier and cheaper.

Chapter 2 - Literature Survey/Review

            Tursi, (2019) presupposes that biomass is currently the most known and prevalent fromof renewable energy. Its usage has become popular amongst people because its production does address various concerns that have been raised regarding global warming and climate change being affiliated with the production of energy and their negative implications to the health of users. Therefore, the replacement of fossil energy with biomass-derived energy could yield positive outcomes from multiple perspectives, especially in connection with health and the environment (Haq et al., 2016). It is on this basis that the article concludes that amongst many resources and renewable technologies, biomass represents the most promising economic lever.

            Notably, the reduction in the usage of fuels derived from petroleum has influenced the shift though it is evident that biofuel is unable to completely write off the use of petroleum and such an assertion comes from the existing engines as well as the production capacity of the petroleum fuel which cannot be halted once. Another disadvantage is related to the use of biofuels is food security since most some biofuels rely on food-grade oil-seeds. Therefore, there is need to identify or develop techniques that can produce biofuel that is compatible with current engines and one whose production cost is manageable (Hassan and Kalam, 2013; Hossain, Zaini, and Mahlia, 2017).  

Lee et al. (2019), notes that existing scientific studies have proved that it is possible for waste and biomass residues to produce various types of bio-energies although its production costs cannot compete other forms of renewable energy or even the petro-fuel. It is on the cost basis that there is an increased attempt to develop cost-effective methods that can efficiently support the conversion of waste and biomass residue. The authors identified that there are two primary conversion techniques known as thermochemical and biochemical techniques. Additionally, they noted that the other techniques if combined with the transesterification technique used in the direct conversion of waste and biomass results to production of bioelectricity. Also, biofuels could be converted using microbial fuel cells and combustion.  

Naik et al., (2010) argued that a sustainable source of energy is crucial for any sustainable economic and industrial growth to occur. Noting the unsustainability of the first-generation of biofuels due to the possible stress that their production puts on food commodities, there is need to move towards purifying organic chemicals and materials under environmentally friendly conditions. Such processes have proved to be able to generate ethanol, cellulose, and biofuel. This argument is supported by Sims et al., (2010) who observed that with the exception of sugarcane ethanol, the production of first-generation bio-fuels from food crops is increasingly becoming limited. Despite its expensive nature, if modified, the biochemical approach would reduce the production costs of the second generation biofuels.      

On their part, Escobar-Niño et al., (2014) notes that there is a need to come up with a cheaper alternative which comprises new technology for the production of sustainable fuels. Thus, besides esterification and hydrolytic reactions, lipases have been identified as being able to undergo transesterification reactions consequently producing biofuel. Nonetheless, choosing of the lipases that can potentially accomplish transesterification reactions is a complex process and it is for this basis that the number of biodiesel producing lipases available are few.

In their study, Mathiyazhagan and Ganapathi (2011) analysed the circumstances that significantly influence the transesterification reaction and found that the most important factors include the catalyst concentration, temperatures, the time taken for the reaction to occur, and finally the molar ration of alcohol. Accordingly, they argued that transesterification and pyrolysis are often used in making the ethanol less viscous during its production (Abnisa and Wan Daud, 2014). The main reason for using this method is to help in the reduction of the viscosity of fat and oil using a catalyst that is either acid or base together with ethanol or methanol (Bridgwater, 2012).

In relation to transesterification, Meher, Vidyasagar and Naik (2006) argue that it is est described as to be the process where fat or oil is reacted with a monohydric catalyst. Factors that do influence the nature of the transesterification process include the condition of the reaction, the temperature of the reactants, the type as well as the amount of catalyst used, the type of alcohol uses and finally the molar ratio of the alcohol. In addition, the ethanolysis was argued to be among the most important aspects in the production of biodiesel since ethanol obtained from renewable biomass (Al-Sabagh et al., 2016). Contrarily, during this process, less ethyl esters are produced compared to the methyl esters and the main challenge affiliated with this process is the separation of glycerol.  

Byadgi and Kalburgi (2016), discussed the production of ethanol from used newspaper which they argue that it is one of the largest constituent of the solid waste in the municipal. As a cellulosic feed stock, newspaper has proved to be an attractive option in the generation of bio-ethanol since its feedstock costs are low and its potential for being a fossil fuel displacement is high. Besides its capacity to greenhouse gas emission is low as compared to using corn or sugarcane (Sanford et al., 2017). Regardless of economic and technical difficulties, renewable lignocellulosic raw materials are beneficial in that they eliminate completion with food stocks and as such stimulating sustainability.

Bušić et al. (2018) presupposes that one challenge faced in the production of bioethanol is reduction of its production cost. Therefore, the concept of bio-refinery is required to utilize renewable feed-stocks more efficiently and to produce additional coproducts with additional value which would result in lowered production costs of bioethanol. Accordingly, such an approach would see bioethanol being more economically competitive unlike other fossil fuels available (Miandad et al., 2019).

Fukuda, Kondo and Noda (2001), opined that numerous techniques of producing biofuel have been developed, including transesterification through the use of alkali-catalysis which, within a short time, efficiently converts triglycerides to their respective or rather corresponding methyl esters. In fact, the enzymatic transesterification through lipase has turned to be the most effective form of producing biodiesel. This is because the glycerol which is a waste product in this process can be retrieved. Also, the process of refining the fatty methyl esters is achieved with ease (Syamsiro et al., 2014).

However, commercialization of this process is faced with only one challenge or rather limitation and that is the lipase's production cost. It could be reverted through the use of engineering technology which develops high levels of expression or stability towards ethanol. The nature of alcohol too as well as the oil molar ratio does play a role in influencing the method bound to be used in the production of the biodiesel (Musa, 2016).

Chapter 3: Fundamentals- Definitions of words

• Biofuels: Types of fuel that is generated from biomass through contemporary processes, rather for the natural or geological processes that involve the formation of fossil fuels.
• Bioethanol: it is a fuel type produced from plants like sugarcane and corn
• Transesterification:  when an alkoxy ester compound group is substituted with a different alcohol in catalysed process, it is referred to as transesterification.
• Pyrolysis: It is an irreversible change of the chemical composition of elements and often relies on the thermal decomposition of those elements at very high temperatures.
• Fatty methyl esters (FAME): Refers to a form of fatty acid ester that are gotten when fats are trans esterified with methanol
• Lignocellulosic raw materials: Lignocellulose defines biomass (plant dry matter) often referred to as lignocellulosic biomass. Lignocellulosic raw  materials are predominantly available for the manufacturing of biofuels, and especially bio-ethanol
• Ethanolysis: Refers to the alcoholysis reaction that uses ethanol as the alcohol solvent.
• Methanolysis: It entails the treatment of PET with methanol, in a pressure of approximately 200°C and whose outcome, depolymerisation, consequently leads to production of ethylene glycol (EG) and dimethyl terephthalate (DMT).
• First-generation biofuels: any fuel sourced from substances such as starch, sugar and animal fats as well as vegetable oil is referred to as the first generation biofuel. These fuels are produced through conventional production methods.
• Second-generation biofuels: Also referred to as advanced biofuels these are fuels that can be produced from various non-food biomass types.

Chapter 4: Methodology

In this chapter the core intention is to present the philosophical assumptions supporting the current research, in addition to introducing the empirical techniques and research strategy employed. Further, it defines the scope and limits of the applied research design, and positions the study amongst existing research traditions in waste management and engineering.

Accordingly, the philosophical assumptions guiding this study are gotten from the interpretive tradition. This means that the ontological and subjective epistemology belief that reality is constructed socially. The adopted research strategy will be to evaluate multiple case studies in within the UK. Accordingly, the fieldwork will be conducted at specific sites within major municipalities and a solid correspondence will be maintained with diverse informants in each site. Accordingly, the primary technique of collecting data that will be employed in this study entails, participant observation, semi-structured interviews, documentation analysis, group discussion, and questionnaires.

Chapter 5: Results and Discussion

The replacement of fossil energy with biomass-derived energy is a reality and is gaining fame due to its positive association with health and the environment (Haq et al., 2016). Nonetheless, a key disadvantage is that it has been criticized as a threat to food security although this has led to increased study on how techniques can be identified and developed to facilitate the production of biofuels that are cost effective and compatible with current engines. Hitherto, factors necessary for transesterification and pyrolysis to take place include reaction time, alcohol molar ration, right temperatures for reaction and finally catalyst concentration. Besides, these processes are important since they help in the reduction of viscosity during the production of ethanol (Abnisa and Wan Daud, 2014). That aside, the biggest challenge to the aforementioned process is the high production of ethanol as well as the production costs (Musa, 2016). Hitherto, biomass is considered the best form of energy that can be renewed and its usage has gained fame due to key concerns related to the devastative effects of fossil fuel usage, including global warming, climate change, and their negative effect on health (Tursi 2019).

More so, for the experimental part of this study, the production or rather the manufacturing of biodiesel from sunflower oil and ethanol and the catalyst being sodium hydroxide is looked at. Ideally, what was being looked at was, how the production and the properties of the biodiesel being generated was affected the ethanol: oil ratio as well as the quantity of the catalyst used during production. The main properties of the biodiesel being looked at were viscosity, density, and refractive. The experiment showed that the ratio of ethanol to oil influences production of biodiesel. Summarily, the produced amount of biodiesel increased as the ethanol to oil ratio increased.

Chapter 6: Conclusion

Noting the ever escalating prices of petroleum products, there is a possibility that in the near there will be a significant shortage of petrochemicals. From the literature search it is evident that numerous alternatives for the production of energy and fuel are inevitable. Besides, this matter is further augmented by the emission of greenhouse gases as well as the witnessed impacts of global warming. To overcome these environmental issues, new methods of developing contemporary catalytic systems that are sustainable and cost effective in relation to the production of alternative energy and fuel is essential. Accordingly, the current study not only discussed the importance of the ethanol as a biofuel, but its sources and techniques of producing it. In addition, the study evaluated the overall process of producing biofuels from various biomasses and different fatty acids through various catalytic processes, namely transesterification and pyrolysis reactions.