『Abstract
The entire life cycle of biodiesel produced by microalgal biomasses
was evaluated using the method of life cycle assessment (LCA)
to identify and quantify the fossil energy requirements and environmental
impact loading of the system. The life cycle considers microalgae
cultivation, harvesting, drying, oil extraction, anaerobic digestion,
oil transportation, esterification, biodiesel transportation and
biodiesel combustion. The investigation results show that the
fossil energy requirement for the biodiesel production is 0.74
MJ/MJ biodiesel, indicating that 1 MJ of biodiesel requires an
input of 0.74 MJ of fossil energy. Accordingly, biodiesel production
is feasible as an energy producing process. The environmental
impact loading of microalgal biodiesel is 3.69 PET2010
(Person Equivalents, Targeted, in 2010) and the GWP is 0.16 kg
CO2-eq/MJ biodiesel. The effects of photochemical
ozone formation were greatest among all calculated categorization
impacts. The fossil energy requirement and GWP in this operation
were found to be particularly sensitive to oil content, drying
rate and esterification rate. Overall, the results presented herein
indicate that the cultivation of microalgae has the potential
to produce an environmentally sustainable feedstock for the production
of biodiesel.
Keywords: Life cycle assessment; Miocroalgae; Biodiesel』
1. Introduction
2. Methodology
2.1. Overall approach
2.2. Definition of goal and scope
3. Unit process and life cycle inventory
3.1. Data collection and validation of data
3.2. Cultivation and treatment of microalgae
3.2.1. Cultivation of microalgae
3.2.2. Harvesting
3.2.3. Drying
3.3. Microalgal oil extraction and refining
3.4. Transport of microalgal oil and biodiesel
3.5. Anaerobic digestion and biogas combustion
3.6. Esterification
3.7. Biodiesel combustion
4. Impact assessment
4.1. Energy consumption
4.2. Environment impact assessment
4.2.1. Characterization
4.2.2. Normalization and weighting
5. Sensitivity analysis
6. Discussion
7. Conclusions
Acknowledgments
References