Self-recuperative high temperature co-electrolysis-based methanol production with vortex search-based exergy efficiency enhancement Yus Donald Chaniago a, 1 , Muhammad Abdul Qyyum a, 1 , Riezqa Andika b , Wahid Ali c , Kinza Qadeer a , Moonyong Lee a, * a School of Chemical Engineering, College of Engineering, Yeungnam University, Gyeongsan, Republic of Korea b Department of Chemical Engineering, Faculty of Engineering, Universitas Indonesia, Depok, 16424, Indonesia c Department of Chemical Engineering and Technology, Jazan University, Jazan, 45971, Saudi Arabia article info Article history: Received 12 March 2019 Received in revised form 9 August 2019 Accepted 12 August 2019 Available online 13 August 2019 Handling editor: Giorgio Besagni Keywords: Solid oxide electrolyzer cell Co-electrolysis Self-heat recuperation Vortex search Exergy analysis Methanol abstract The reduction of greenhouse gas emission via the transformation of carbon dioxide into methanol results in several secondary benefits including the production of a valuable by-product that can be used for energy storage and as a fuel source. As such, this is a promising approach for mitigating climate change. Methanol production via the co-electrolysis process using solid oxide electrolyzer cells is an efficacious solution to the issue of excess electricity storage in the context of renewable energy and carbon dioxide utilization. However, this process is an energy-intensive and temperature-sensitive method, mainly due to the requirement of high-temperature electrolysis. In this context, this study investigates and evaluates the potential for overall performance improvement by minimizing energy consumption and increasing methanol production using self-heat recuperation technology. The newly developed vortex search strategy was employed to achieve the maximum potential benefit from retrofitted recuperators. Detailed exergy analysis was performed for the process and the evaluation of its performance. The findings revealed that the electrochemical system for co-electrolysis has the highest exergy destruction rate. By employing the vortex search approach, the exergy loss of the energy process system can be reduced by 61.7% with a total reduction of the exergy loss of 15.9%, while improving methanol production and decreasing distillation reboiler duty. The simple solution of self-recuperation with optimization that was utilized in this study is a flexible approach that can be directly applied to the improvement of co- electrolysis and methanol synthesis. © 2019 Elsevier Ltd. All rights reserved. 1. Introduction Fossil fuel use has increased atmospheric carbon dioxide (CO 2 ) emission levels in recent years, leading to problems related to the environment and public health including climate change and air pollution. This major issue of CO 2 emission has resulted in the global monitoring of this gas (Witze, 2018). Moreover, there has been substantial efforts to limit the carbon footprint of the world's population by emphasizing the use of renewable energy such as hydropower (Bello et al., 2018), biogas energy (Haider et al., 2019), and solar photovoltaic systems (Parida et al., 2011) as power sources. In addition, other technologies have been exploited to facilitate the improvement of CO 2 electroreduction into useful fuels (Gao et al., 2016) and the transition to solar, wind, and geothermal energy (Mekonnen et al., 2016). However, not all renewable energy alternatives results in a reduction of CO 2 emissions. In the worst case, a renewable energy fails to offset the emitted CO 2 , e.g., biofuel production (DeCicco et al., 2016). Renewable energy intermittency is another drawback, e.g., in May 2016, in Germany, electricity supply far exceeded demand and the price of electricity became negative, and consumers were paid for their electricity consump- tion (Andika et al., 2018). Thus, there is a need for systems that can use excess electrical energy, in anticipation of positive renewable growth towards 2023 (Gielen et al., 2019). In addition, CO 2 is an essential material for many industrial processes (Pierantozzi, 2003). To address the aforementioned issues, several promising solutions have been proposed in which CO 2 emissions are reduced and converted into useful products, energy storage and fuels, that are both environmentally and economically beneficial * Corresponding author. E-mail address: mynlee@yu.ac.kr (M. Lee). 1 These authors contributed equally to this work. Contents lists available at ScienceDirect Journal of Cleaner Production journal homepage: www.elsevier.com/locate/jclepro https://doi.org/10.1016/j.jclepro.2019.118029 0959-6526/© 2019 Elsevier Ltd. All rights reserved. Journal of Cleaner Production 239 (2019) 118029