**4. Conclusions**

In the present work, an alternative methodology to the chemical transformation of vegetable oil for being employed as biofuels is presented. This methodology consists of a dissolution process of the oil in a suitable solvent, in order to reduce its viscosity to the appropriate level demanded by the EN 590 standard. Specifically, we studied the use of gasoline as a solvent to obtain double blends of gasoline/oil, which are employed as LVLC in blends with fossil diesel. In this sense, two different commercial vegetable oils have been employed, sunflower oil and castor oil. According to the results here reported, the following conclusions have been obtained: The substitution of more than 40% of fossil diesel can be achieved by the use of triple blends of diesel/gasoline/sunflower oil, whereas 25% of fossil diesel can be substituted employing their counterparts with castor oil.


In summary, this research show, for the first time, that the substitution of diesel fuel for gasoline allows the incorporation of higher percentages of pure vegetable oils, generating second-generation biofuels capable of operating in current CI engines without making any mechanical modification in them. In addition, through the use of these triple blends of diesel/gasoline/vegetable oil, the objectives proposed by the EU in the next decades can be achieved, making possible the gradual substitution of fossil fuels by directly using vegetable oils, without performing any type of transesterification process. Therefore, this research opens a practical and economically viable alternative to the chemical production of biofuels.

**Author Contributions:** This research article is part of the doctoral thesis of B.H., directed by professors D.L. and F.M.B., who in a general way conceived and designed the experiments and wrote the paper. C.L., A.A.R., B.H.C. and R.E. made substantive intellectual contributions to this study, making substantial contributions to conception and design of it, as well as to the acquisition, analysis and interpretation of data. Furthermore, D.L. and R.E wrote the paper. All the authors have also been involved in drafting and revising the manuscript, so that everyone has given final approval of the current version to be published in the Energies journal.

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

**Acknowledgments:** This research is supported by the MEIC funds (Project ENE 2016-81013-R), Junta de Andalucía and FEDER (P11-TEP-7723), that cover the costs to publish in open access.

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