*Article* **Pre-Feasibility Study of a Multi-Product Biorefinery for the Production of Essential Oils and Biomethane**

**Luís Carmo-Calado <sup>1</sup> , Roberta Mota-Panizio 1,\* , Ana Carolina Assis <sup>1</sup> , Catarina Nobre <sup>1</sup> , Octávio Alves <sup>2</sup> , Gonçalo Lourinho <sup>2</sup> and Paulo Brito <sup>1</sup>**


**Abstract:** Rural areas can benefit from the development of biorefineries for the valorization of endogenous feedstocks. In this study, a pre-feasibility assessment of an integrated multi-product biorefinery to produce essential oils and biomethane is carried out considering current technical and economic conditions. The proposed concept is based on the steam distillation of forestry biomass for the extraction of essential oils (2900 L/y) followed by biomethane production via syngas methanation using the spent biomass as feedstock (30.4 kg/h). In parallel, the anaerobic treatment of WWTP sludge (5.3 kg/h) is used to produce additional biomethane for mobile applications. The results show that the intended multi-product biorefinery delivers attractive benefits for investors as described by the calculated financial indicators: NPV of EUR 4342.6, IRR of 18.1%, and PB of 6 years. Overall, the pre-feasibility analysis performed in this study demonstrates that the proposed biorefinery concept is promising and warrants further investment consideration via cost and benefit analysis, ultimately promoting the implementation of multi-product biorefineries across Europe.

**Keywords:** biorefineries; gasification; essential oils; biomass wastes; biomethane

**Citation:** Carmo-Calado, L.; Mota-Panizio, R.; Assis, A.C.; Nobre, C.; Alves, O.; Lourinho, G.; Brito, P. Pre-Feasibility Study of a Multi-Product Biorefinery for the Production of Essential Oils and Biomethane. *C* **2023**, *9*, 2. https://doi.org/10.3390/c9010002

Academic Editors: Indra Pulidindi, Pankaj Sharma and Aharon Gedanken

Received: 16 November 2022 Revised: 20 December 2022 Accepted: 21 December 2022 Published: 24 December 2022

**Copyright:** © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).
