Life Cycle Assessment (LCA) of Biodiesel Production from Waste Cooking Oil in Comparison with Petroleum Diesel

CHAPTER ONE

INTRODUCTION

1.1 Background to the Study

The growing demand for energy has brought increased attention to the environmental impact of fossil fuels. Petroleum diesel, although widely used in transportation and industry, contributes significantly to greenhouse gas emissions, air pollution and climate change (International Energy Agency, 2022). As global concerns about sustainability intensify, many researchers and policymakers continue to explore cleaner alternatives. Biodiesel has emerged as a promising renewable fuel because it is biodegradable, emits fewer pollutants and can be produced from various biological feedstocks (Demirbas, 2009).

Waste cooking oil (WCO) is one of the most attractive feedstocks for biodiesel production. It is inexpensive, widely available and helps reduce the environmental burden associated with improper oil disposal. Transforming WCO into biodiesel supports circular economy principles by converting waste into a valuable energy resource (Gui et al., 2008). In addition, using WCO avoids the ethical concerns linked to edible oil–based biodiesel, such as food–fuel competition (Atabani et al., 2012).

However, the sustainability of biodiesel must be evaluated beyond emission reductions during combustion. Life Cycle Assessment (LCA) provides a holistic framework for assessing environmental impacts from resource extraction to end use. Studies show that LCA helps identify hotspots in biodiesel production, including energy use during transesterification, methanol consumption and feedstock collection logistics (Roy et al., 2021). Compared with fossil diesel, biodiesel from WCO often demonstrates lower carbon emissions, though some impacts—such as eutrophication or water consumption—may remain significant (Yang et al., 2019).

Because environmental benefits vary across regions, technologies and feedstock sources, conducting an LCA for WCO-based biodiesel within local conditions is essential. This study evaluates the environmental performance of WCO biodiesel in comparison with petroleum diesel using a standardized LCA approach.

1.2 Statement of the Problem

Although biodiesel from waste cooking oil is often described as environmentally friendly, its overall sustainability is not uniform across production systems. Variations in feedstock collection, transportation distance, energy sources, catalyst type and conversion efficiency can alter environmental outcomes (Roy et al., 2021). Without context-specific assessments, decision-makers may rely on assumptions that do not accurately reflect real environmental impacts.

In many developing regions, WCO management remains poor. Large volumes of used oil are discharged into drainage systems or soil, creating environmental hazards (Kotronia et al., 2020). Converting this waste into biodiesel could reduce pollution; however, the environmental benefits must be quantified. Petroleum diesel, despite its emissions, benefits from mature production processes and established supply chains. Therefore, a direct comparison is required to determine whether WCO biodiesel offers clear environmental advantages.

There is also limited research on LCA-based comparisons of WCO biodiesel and fossil diesel within the local Nigerian context. Without such data, policymakers and industries cannot make informed decisions about renewable fuel adoption. This study addresses these gaps by analyzing the life cycle environmental impacts of both fuels.

1.3 Aim of the Study

The aim of this study is to conduct a Life Cycle Assessment of biodiesel produced from waste cooking oil and compare its environmental impacts with those of petroleum diesel.

1.4 Objectives of the Study

The specific objectives are:

1. To collect and characterize waste cooking oil as a biodiesel feedstock.

2. To produce biodiesel using standard transesterification processes.

3. To perform an LCA of WCO biodiesel using recognized ISO 14040/14044 guidelines.

4. To evaluate key environmental impact categories including global warming potential, energy use and resource depletion.

5. To compare these impacts with those of petroleum diesel production and use.

1.5 Research Questions

1. What environmental impacts are associated with biodiesel production from waste cooking oil

2. How do these impacts compare with the life cycle impacts of petroleum diesel

3. Which stages of biodiesel production contribute most to environmental burden

4. Does WCO biodiesel offer measurable environmental benefits

5. What improvements can enhance biodiesel sustainability

1.6 Research Hypotheses

H1: Biodiesel produced from waste cooking oil has a significantly lower global warming potential than petroleum diesel.
H0: Biodiesel produced from waste cooking oil does not have a significantly lower global warming potential than petroleum diesel.

1.7 Significance of the Study

This study contributes to renewable energy research by providing evidence-based insights on the environmental performance of WCO biodiesel. It supports policymakers in evaluating whether biodiesel should receive stronger incentives within national energy strategies. Furthermore, the study promotes sustainable waste management by demonstrating the environmental value of recycling cooking oil rather than disposing of it improperly.

Industries involved in fuel production, transportation and food services may also benefit. An improved understanding of biodiesel’s life cycle helps investors and regulators identify areas where process efficiency can be strengthened. Additionally, the study supports global climate goals by examining alternatives that reduce greenhouse gas emissions (IPCC, 2021).

1.8 Scope of the Study

The study focuses on the life cycle environmental impacts of biodiesel derived from waste cooking oil. It covers feedstock collection, transportation, biodiesel production, distribution and combustion. Petroleum diesel is assessed using secondary LCA data. Economic analysis and engine performance testing fall outside the scope.

1.9 Limitations of the Study

Several limitations may influence the study. Regional variations in WCO composition may affect processing efficiency (Gui et al., 2008). In addition, some life cycle inventory (LCI) data may rely on secondary sources, which may not fully capture local conditions. Despite these constraints, the study uses ISO-standard LCA methods to ensure credible and transparent results.

1.10 Organization of the Study

The research is organized into five chapters. The first chapter introduces the study and outlines its problem, aim and scope.  Review of literature on biodiesel production, waste cooking oil management and LCA principles is presented in chapter two. Chapter Three describes the methodology, including data collection and LCA procedures. Chapter Four presents the results and discusses the environmental implications. The final chapter concludes the work and provides recommendations for improving biodiesel sustainability.

References

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Demirbas, A. (2009). Progress and recent trends in biodiesel fuels. Energy Conversion and Management, 50(1), 14–34.

Gui, M. M., Lee, K. T., & Bhatia, S. (2008). Feasibility of edible oil vs. waste edible oil as biodiesel feedstock. Energy, 33(11), 1646–1653.

International Energy Agency. (2022). World Energy Outlook 2022. IEA Publications.

IPCC. (2021). Climate Change 2021: The Physical Science Basis. Cambridge University Press.

Kotronia, M., Karapanagioti, H., Kalderis, D., & Samaras, P. (2020). Waste cooking oil management: A review of environmental impacts and sustainable practices. Journal of Environmental Management, 276, 111–123.

Roy, P., Dias, G., de Souza, R., & Lilley, D. (2021). Life cycle assessment of biodiesel production from waste cooking oil: A review. Journal of Cleaner Production, 300, 126–152.

Yang, L., Zhang, Y., Li, J., & Chen, G. (2019). Life cycle assessment of biodiesel from waste cooking oil: A case study in China. Waste Management, 87, 403–411.