Turning Waste into Wealth: A New Perspective on Potato Peel Waste and Bioenergy

A report by chemical and sustainable development engineering students at Tecnológico de Monterrey University in Mexico

Please note: What follows in this document is a summarized version of the final, full report. The full report can be obtained from corresponding author Adolfo Franco Valdez Gurrola. He can be reached at franco.vzga@gmail.com

Final report compiled and produced by:

Adolfo Franco Valdez Gurrola
Daniela Gutiérrez Fraige
Eugenia García Castañeda
Marco Antonio Hernández Casanova
Marlene Arleth Mendieta De la Torre

Presented to:

Dr. Alberto Mendoza Domínguez, Tecnológico de Monterrey University. Lecturer: Technologies for the Efficient Use of Thermal Energy course

June 19, 2023

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Executive Summary

This Report by a team of students at the Tecnológico de Monterrey University in Mexico presents a pioneering approach to the global waste management challenge, emphasizing the untapped potential of organic waste, specifically potato peel waste (PPW), as a source of renewable energy. Through a detailed analysis, the Report suggests a paradigm shift from viewing waste as a disposal problem to recognizing it as a valuable resource for energy generation.

The Report first highlights the issue of waste management, with a focus on organic waste, which constitutes a significant portion of municipal solid waste. It underscores the potential of PPW as a promising biomass feedstock, capable of producing bio-oil, biochar, and syngas through the process of pyrolysis.

A detailed analysis of potato peel wastes and bio-char, including their elemental and proximate analysis, are presented, providing a comprehensive understanding of the energy potential of this biomass waste. The Report also delves into the economic aspects, revealing that a ton of humid potato peel waste could generate a total profit of US$347 per ton of potato, considering the tipping fee cost and the profit from the bio-oil, biogas, and biochar.

The Report further explores the comparison between pyrolysis and gasification, two thermochemical processes used to convert organic feedstocks into gaseous or liquid fuels. It acknowledges the economic challenges faced by pyrolysis products in competing with fossil fuels due to their high production costs.

A compelling case study of Sabritas, a snack company, is presented to demonstrate the practical application of the waste-to-energy strategy using potato peel waste. The proposed strategy involves installing a pyrolysis reactor near Sabritas’ largest plant located in the Vallejo neighborhood of Mexico City, which could generate about 1,178 kW of energy.

The Report concludes by stressing the sustainable development implications of the proposed waste-to-energy strategy. The authors assert that the implementation of sustainable bioenergy practices can contribute to decarbonization goals, provide economic and social benefits, improve energy security, and job creation.

In essence, the Tecnológico de Monterrey Report presents a robust and promising proposition for managing organic waste while contributing to renewable energy production. The Report’s findings underscore the untapped potential of potato peel waste, redefining it from a mere waste product to a valuable resource for energy generation.

Introduction: The Waste Management Problem and Potential Solutions

The challenge of waste management is a globally recognized problem. As the global population and consumption patterns continue to grow, so does the generation of waste. It is estimated that around 2 billion tons of municipal solid waste are produced annually worldwide, a figure that is expected to rise in the coming years.

The problem is twofold. On one hand, improper waste management leads to numerous environmental issues, including soil, water, and air pollution, and contributes to climate change. On the other hand, landfilling, the most common waste management method, is unsustainable in the long term due to limited land availability and the loss of potentially valuable resources that are discarded as waste.

The Tecnológico de Monterrey Report presents a unique approach to address this issue by focusing on organic waste, particularly potato peel waste (PPW), which constitutes a significant portion of municipal solid waste. Organic waste, if not managed correctly, can lead to the emission of methane, a potent greenhouse gas, during decomposition.

The Report proposes to convert organic waste, such as PPW, into bioenergy through thermochemical processes like pyrolysis and gasification. This not only provides a sustainable solution for waste management by diverting waste from landfills but also contributes to renewable energy generation.

Such a waste-to-energy approach offers a dual solution to a pressing problem: it helps manage and reduce waste while simultaneously providing a source of renewable energy. This approach is in alignment with the principles of a circular economy, which emphasizes waste minimization and the optimal utilization of resources. By turning waste into a resource, we can move towards more sustainable and resilient waste management and energy production systems.

Understanding Biomass Waste: Potato Peel Waste as a Biomass Feedstock

The Report commences by shedding light on the issue of waste management. Potato peel waste (PPW), an often-overlooked byproduct of the food industry, especially in snack production, possesses untapped potential. It underlines that globally, around 2 billion tons of municipal solid waste are generated annually, with organic waste constituting a significant portion. Thus, efficiently utilizing organic waste, such as PPW, can provide an effective solution for waste management while also contributing to energy generation.

Biomass waste comprises organic materials such as agricultural residues, forestry waste, and certain types of industrial wastes. Potato peel waste (PPW) is one such type of biomass waste that arises in large quantities, particularly in the food processing industry. Every year, billions of tons of potatoes are processed worldwide to produce various products, including chips, fries, and other potato-based foods. The peelings from these potatoes often constitute a significant portion of the overall waste generated by these industries.

PPW is rich in organic matter, making it a promising feedstock for the production of bioenergy. It contains carbohydrates, proteins, and other compounds that can be broken down and converted into useful products such as biofuels. For instance, the starch in potato peels can be fermented to produce bioethanol, a renewable fuel that can replace gasoline in vehicles.

In addition to its potential as a bioenergy source, PPW also offers other benefits. It is a type of waste that is produced in large volumes and is often considered a disposal problem by the industries that generate it. By using PPW as a feedstock for bioenergy production, these industries can not only solve a waste disposal problem but also contribute to the production of renewable energy.

Furthermore, the use of PPW for bioenergy production aligns with the principles of the circular economy, a model that aims to keep resources in use for as long as possible, extract the maximum value from them while in use, then recover and regenerate products and materials at the end of each service life. Instead of being discarded and ending up in landfills, PPW can be transformed into a valuable resource, closing the loop and contributing to a more sustainable and efficient use of resources.

In conclusion, understanding the potential of biomass waste like PPW is crucial in our quest for sustainable development. Such knowledge can lead to innovative solutions that address multiple challenges – from waste management to energy production – paving the way for a more sustainable and resilient future.

The Science of Conversion: An In-depth Look at Pyrolysis and Gasification

The Report further elaborates on the energy potential of biomass waste, underscoring the utility of PPW as a promising biomass feedstock. The conversion of biomass waste into bioenergy is a proven method for renewable energy production. PPW, with its considerable organic content, emerges as a suitable candidate for this conversion, with the potential to produce bio-oil, biochar, and syngas through pyrolysis.

Pyrolysis and gasification are two advanced thermal treatment technologies that convert biomass, such as potato peel waste, into useful products. They are both thermochemical processes, meaning they use heat and chemical reactions to change the physical and chemical properties of the biomass.

Pyrolysis

Pyrolysis involves heating biomass in the absence of oxygen, causing it to break down into smaller molecules. This process typically occurs at temperatures between 350 and 600°C. The absence of oxygen prevents the biomass from combusting, allowing it to decompose into various useful products. These include a solid residue called biochar, a liquid known as bio-oil, and a mixture of gases referred to as syngas.

Biochar is a carbon-rich solid that can be used as a soil amendment to improve soil health. Bio-oil can be upgraded and used as a substitute for fossil fuels in many applications, while syngas, a mixture of hydrogen, carbon monoxide, and other gases, can be used to generate electricity or as a feedstock for producing chemicals.

Gasification

Gasification, on the other hand, partially oxidizes the biomass at high temperatures, typically between 800 and 1000°C. This process is carried out in the presence of a controlled amount of oxygen or steam, which prevents the complete combustion of the biomass. The main product of gasification is a hydrogen-rich syngas, which can be used to generate electricity, heat, or as a building block for producing chemicals and fuels.

Gasification is particularly effective for generating clean, renewable energy from biomass. The gasification process is flexible and can be adjusted to produce syngas with the desired composition. For instance, by tweaking the process conditions, it’s possible to maximize the production of hydrogen, a clean-burning fuel, in the syngas.

Both pyrolysis and gasification offer promising ways to convert biomass waste into valuable products. They can help reduce dependence on fossil fuels, reduce greenhouse gas emissions, and contribute to a circular economy where waste is not just discarded but used as a valuable resource.

However, it’s important to note that both processes face challenges, including high operating costs, the need for careful process control, and the need for treatment or utilization of by-products. Despite these challenges, pyrolysis and gasification remain promising technologies for sustainable waste management and renewable energy production.

Analyzing Potato Peel Wastes and Bio-char: Elemental and Proximate Analysis

Understanding the properties and potential of potato peel waste (PPW) and bio-char is a central focus of the Tecnológico de Monterrey Report. To achieve this, the authors conduct an elemental and proximate analysis of these substances.

Elemental Analysis

Elemental analysis provides a quantitative measurement of the major elements present in PPW and bio-char, such as carbon, hydrogen, nitrogen, sulfur, and oxygen. This information is crucial because the elemental composition influences the behavior of these materials during thermochemical processes like pyrolysis and gasification.

For example, a higher carbon content generally leads to a higher heating value, making the material a better source of energy. Similarly, a high oxygen content may lower the heating value but increase the reactivity of the biomass, affecting the efficiency of the conversion process.

Proximate Analysis

Proximate analysis, on the other hand, measures the moisture, volatile matter, fixed carbon, and ash content of the biomass. These properties play a significant role in determining the suitability of PPW for energy production.

Moisture content is important because high moisture levels can lower the heating value of the biomass and make it more difficult to process. Volatile matter refers to the components of the biomass that are released as gases during heating. A higher volatile matter content typically leads to a higher yield of gaseous products during pyrolysis or gasification.

Fixed carbon represents the portion of the biomass that remains as a solid residue after the volatile matter has been released. This can be converted into biochar, a valuable byproduct that can be used as a soil amendment or as a fuel.

Lastly, ash content is the inorganic residue that remains after complete combustion of the biomass. While a high ash content can cause operational problems in thermochemical conversion processes, some ash components, such as potassium and phosphorus, can be beneficial for the agricultural use of biochar.

By conducting a thorough elemental and proximate analysis, the authors of the Tecnológico de Monterrey Report provide valuable insights into the energy potential of potato peel waste and bio-char. This analysis helps pave the way for the efficient and sustainable conversion of this waste into bioenergy, contributing to renewable energy generation and sustainable waste management.

Economic Assessment: Unveiling the Profit Potential of Potato Peel Waste

In the Tecnológico de Monterrey Report, the authors undertake an economic assessment of the process of converting potato peel waste (PPW) into bioenergy. Their findings reveal the potential for significant financial benefits from this waste-to-energy approach.

The Report proposes that the bio-oil, biogas, and biochar derived from the PPW can each be sold for profit. Bio-oil, a liquid fuel that can be used as a substitute for fossil fuels in many applications, is valued at US$0.94 per gallon. Biogas, a mixture of gases that can be used to generate electricity or heat, is valued at US$540 per ton. Biochar, a carbon-rich solid that can be used as a soil amendment, is valued at US$346 per ton.

In addition to the direct sale of these products, the Report suggests that there could be additional income from the tipping fees associated with waste disposal. The current tipping cost, which is the fee charged for waste disposal, is US$60.34 per ton of waste.

Based on these numbers, the authors calculate that a ton of humid potato peel waste could generate a total profit of US$347 per ton of potato. This calculation takes into account the tipping fee cost and the profit from the bio-oil, biogas, and biochar.

It’s worth noting that these figures are estimates and the actual profits could vary depending on a range of factors, including the cost of the pyrolysis or gasification process, the market prices for the products, and the quality of the potato peel waste. Despite these variables, the analysis makes a compelling case for the economic potential of converting potato peel waste into bioenergy.

The economic assessment provided by the Tecnológico de Monterrey Report shines a spotlight on the potential profitability of bioenergy production from PPW. It reveals the possibility of transforming what is often seen as a waste disposal problem into a profitable venture. This reimagining of waste as a valuable resource underscores the potential of a circular economy approach in which waste is not just discarded but is used to create value.

Comparative Study: Pyrolysis vs. Gasification for Energy Generation

Pyrolysis and gasification are two key thermochemical processes utilized to convert organic matter, such as potato peel waste, into valuable end products. While both processes involve the application of heat and occur in an oxygen-limited environment, their operational parameters and outcomes can differ significantly.

Pyrolysis

Pyrolysis involves heating the biomass in a virtually oxygen-free environment, which prevents combustion and allows the organic matter to thermally decompose. This process typically occurs at temperatures ranging from 350 to 600°C. The resulting products are a mix of solid (biochar), liquid (bio-oil), and gaseous (syngas) compounds.

The proportions of these products can be controlled by adjusting the pyrolysis conditions. For instance, slow pyrolysis at lower temperatures and longer residence times favors the production of biochar, while fast pyrolysis at higher temperatures and shorter residence times results in a higher yield of bio-oil. The syngas produced, although usually a minor fraction, can be harnessed for heat generation during the pyrolysis process itself.

Gasification

Gasification, in contrast, involves the partial oxidation of biomass at higher temperatures, typically between 800 and 1000°C. While pyrolysis completely excludes oxygen, gasification introduces a limited amount of oxygen or steam. This controlled oxidation allows the biomass to undergo a series of thermochemical reactions, producing a gas mixture rich in carbon monoxide and hydrogen, commonly known as syngas.

The syngas from gasification can be used as a fuel for heat and electricity generation, or it can be further processed to produce fuels like synthetic natural gas (SNG) or chemicals like methanol. A small amount of solid residue, or char, is also produced during gasification, which can be utilized as a soil amendment or gasified further.

Pyrolysis vs. Gasification

While both processes offer the potential to convert biomass waste into valuable energy products, there are key differences. Gasification generally results in a higher yield of syngas with a higher energy content, making it more suitable for applications requiring gas fuels or for further synthesis into other fuels and chemicals. Pyrolysis, on the other hand, produces a more significant fraction of bio-oil, which can be used directly as a fuel or processed into other liquid fuels.

The choice between pyrolysis and gasification ultimately depends on several factors, including the specific characteristics of the biomass feedstock, the desired end products, and the specific economic and environmental considerations of the project. Both technologies, however, offer promising pathways to harness the energy potential of biomass waste, contributing to renewable energy generation and sustainable waste management.

Real-world Application: The Case of Sabritas and the Proposed Waste-to-Energy Strategy

The Tecnológico de Monterrey Report introduces an intriguing case study of Sabritas, a prominent snack company, to demonstrate the practical application of the waste-to-energy strategy using potato peel waste (PPW).

Sabritas, a major player in the snack industry in Mexico, generates a significant amount of potato waste. Much of this waste comes in the form of potato peelings, which are typically discarded during the production process. Given the scale of Sabritas’ operations, this represents a substantial amount of waste that can be utilized for energy production.

The authors propose installing a pyrolysis reactor near Sabritas’ largest plant, located in the Vallejo neighborhood of Mexico City. The reactor would utilize the potato peel waste generated by Sabritas as a feedstock for energy production. By locating the reactor near the source of the waste, transportation costs can be minimized, improving the overall efficiency and sustainability of the process.

The Report’s calculations estimate that feeding 50 kg of potato peel waste per hour into the pyrolysis reactor could generate about 1,178 kW of energy. This energy is equivalent to powering approximately 267,916.44 LED lights all day long every year. This finding underscores the substantial potential of potato peel waste as a renewable energy source.

By converting their waste into a valuable resource, companies like Sabritas can improve their sustainability, reduce their environmental footprint, and potentially even generate a new stream of revenue or savings. This case study offers an inspiring example of how industries can incorporate circular economy principles into their operations, transforming waste management challenges into opportunities for innovation and sustainability.

Sustainable Development Implications: The Potential Impact on Decarbonization Goals and Energy Security

The sustainable development implications of the proposed waste-to-energy strategy in the Tecnológico de Monterrey Report are far-reaching. The Report emphasizes that converting potato peel waste (PPW) into bioenergy aligns with several sustainability and development goals, bringing environmental, social, and economic benefits.

Decarbonization and Climate Change Mitigation

One of the primary environmental benefits is the potential contribution to decarbonization goals. The combustion of fossil fuels for energy is a significant source of greenhouse gas emissions, which drive climate change. By contrast, bioenergy derived from waste, such as PPW, is considered carbon-neutral. This is because the carbon dioxide released during the combustion of biofuels is offset by the carbon dioxide absorbed from the atmosphere during the growth of the biomass. Thus, replacing fossil fuels with bioenergy can help to reduce greenhouse gas emissions and mitigate climate change.

Energy Security

The strategy also has implications for energy security. Relying on fossil fuels for energy can leave countries vulnerable to fluctuations in global oil prices and geopolitical tensions. In contrast, biomass resources for bioenergy production are often locally available, reducing reliance on imported energy and improving energy security.

Economic Benefits and Job Creation

There are significant economic benefits as well. The process of converting waste into bioenergy can generate new revenue streams from the sale of biofuels and other byproducts. It can also lead to cost savings by reducing waste disposal costs. Moreover, the development of a new bioenergy industry can stimulate economic growth and create jobs. This can be particularly beneficial in rural areas, where biomass resources are often located.

Contributing to Sustainable Development Goals

Finally, the proposed waste-to-energy strategy aligns with several of the United Nations’ Sustainable Development Goals (SDGs). These include SDG 7 (Affordable and Clean Energy), SDG 9 (Industry, Innovation, and Infrastructure), SDG 11 (Sustainable Cities and Communities), and SDG 13 (Climate Action).

The sustainable development implications of the proposed waste-to-energy strategy underscore the potential of this approach to contribute to a more sustainable and resilient future. By transforming waste into a valuable resource, we can not only address the waste management challenge but also generate renewable energy, stimulate economic growth, create jobs, and contribute to climate change mitigation.

Conclusion: A New Perspective on Waste and Energy Production

The Tecnológico de Monterrey Report concludes with a compelling call to action: to reimagine our perspective on waste and energy production. The Report urges us to recognize the significant potential of waste, particularly potato peel waste (PPW), as a valuable resource for generating renewable energy.

The Report underscores the potential of the thermochemical processes of pyrolysis and gasification to convert PPW into bioenergy products such as bio-oil, biochar, and syngas. This process can turn a waste product, often seen as a disposal problem, into a viable source of renewable energy.

The authors emphasize the alignment of this waste-to-energy strategy with sustainable development goals, particularly those related to affordable and clean energy, climate action, and responsible consumption and production. By utilizing waste to produce energy, we can decrease our reliance on fossil fuels, reduce greenhouse gas emissions, and contribute to the transition towards a low-carbon, sustainable energy system.

Moreover, the Report spotlights the significant economic potential of this approach. By valorizing waste, industries can open up new revenue streams, reduce waste disposal costs, and stimulate job creation.

In the case study of Sabritas, the authors demonstrate the practical application of their proposed strategy. They show that a significant amount of energy could be generated from the PPW produced by this snack company, illustrating the real-world potential of their proposal.

In conclusion, the Tecnológico de Monterrey Report offers a fresh perspective on waste and energy production. It challenges us to rethink our approach to waste, urging us to see it not as a problem, but as an opportunity. This shift in perspective can play a pivotal role in our quest for sustainable development, pushing us closer to a future where waste is valued as a resource, renewable energy is the norm, and sustainability is integrated into all aspects of our lives.

Editor & Publisher: Lukie Pieterse


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