*Article* **Valorization of Exhausted Olive Pomace for the Production of a Fuel for Direct Carbon Fuel Cell**

**Najla Grioui 1,2,\*, Amal Elleuch 1,2 , Kamel Halouani 1,2 and Yongdan Li 3,4,5,6**


**Abstract:** In this study, exhausted olive pomace (EOP) biochar prepared by carbonization at 400 ◦C is investigated as a fuel in a direct carbon fuel cell (DCFC) with an electrolyte-supported configuration. The feasibility of using the EOP biochar in the DCFC is confirmed, showing a maximum power density of 10 mW·cm−<sup>2</sup> at 700 ◦C. This limited DCFC performance is compared with other biochars prepared under similar conditions and interrelated with various biochar physico-chemical characteristics, as well as their impact on the DCFC's chemical and electrochemical reaction mechanisms. A high ash content (21.55%) and a low volatile matter (40.62%) content of the EOP biochar are among the main causes of the DCFC's limited output. Silica is the major impurity in the EOP biochar ash, which explains the limited cell performance as it causes low reactivity and limited electrical conductivity because of its non-crystal structure. The relatively poor DCFC performance when fueled by the EOP biochar can be overcome by further pre- and post-treatment of this renewable fuel.

**Keywords:** DCFC; exhausted olive pomace; biochar; electrochemistry; limitations
