**4. Conclusions**

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Using ethanol produced from the lignocellulosic waste for biodiesel production from castor oil has excellent environmental benefits. However, the results of this study showed that the production of biodiesel from the castor oil by transesterification with fossil-based methanol is more economically profitable. In other words, there is a trade-off between economic aspects of the process and environmental issues. Moreover, the sensitivity analysis performed on the price of the main product showed that the price of the primary seed oil is the most important determinant of the price of the final product. This analysis also showed that the production of ethanol has an enormous effect on the price of the final product, i.e., biodiesel.

**Author Contributions:** Conceptualization, M.S. and K.K.; methodology, M.S.; software, V.R.; validation, M.S. and K.K.; formal analysis, V.R. and M.S.; investigation, V.R. and M.S.; resources, M.S.; data curation, V.R. and M.S.; writing—original draft preparation, V.R.; writing—review and editing, M.S. and K.K.; visualization, V.R. and M.S.; supervision, M.S. and K.K.; project administration, M.S. and K.K.; funding acquisition, K.K. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
