Processes 2022, 10, 1503. https://doi.org/10.3390/pr10081503 www.mdpi.com/journal/processes Article Pyrolysis of High-Density Polyethylene Waste Plastic to Liquid Fuels—Modelling and Economic Analysis Sharif H. Zein 1, *, Connor T. Grogan 1 , Osman Y. Yansaneh 1 and Aditya Putranto 2 1 Department of Chemical Engineering, Faculty of Science and Engineering, University of Hull, Kingston upon Hull HU6 7RX, UK; c.t.grogan@hull.ac.uk (C.T.G.); o.yansaneh-2015@hull.ac.uk (O.Y.Y.) 2 Discipline of Chemical Engineering, School of Engineering, Monash University, Bandar Sunway 47500, Malaysia; aditya.putranto1@monash.edu * Correspondence: s.h.zein@hull.ac.uk; Tel.: +44-1482-466-753 Abstract: Recycling of waste plastics has become vital due to the threat to the environment the huge piles of those wastes represent, with research revealing High-Density Polyethylene (HDPEs) as the most dominant waste plastics. Because of their dominance and significant environmental impact, this paper reports the economic potential of recycling HDPE waste plastic into liquid fuels via py- rolysis. A risk and benefit assessment are presented to highlight whether the process has reasonable potential prior to the analysis of its corresponding finances. Aspen HYSYS simulation models were used as the basis for the analysis. From this, preliminary cost estimations for the net present value (NPV) of the process, its economic viability, were determined. It is shown that 100 kg/h of waste is not financially sustainable. Retailing the fuel product at a competitive price of £60/barrel would ultimately bankrupt the business. This is a consequence of the extremely high production cost of £198.40/barrel inducing the complete absence of profitability. Furthermore, the operating expendi- ture is found to be the root cause of the consequential financial decline, totalling £1.46 million per annum. The two most detrimental expenditures for the production cost of the pyrolysis oils were the wages of the skilled operating labour and higher utility fees incurred by the extreme tempera- ture conditions. In addition, an unrealistically optimistic sale price of £300/barrel was also applied to ascertain a positive economic incentive. Even with the increased retail price, the process’ profits are negligible and further highlight the detrimental effect of the undesirably high operational ex- penditures, once more signifying that the process should not commence in its current state. How- ever, executing such a project in developing countries such as Sierra Leone, Senegal, or Kenya where utilities and manpower, among other operational components, are cheaper, is believed to comple- ment the immense opportunity underlying pyrolysis oil production regarding production quantity and quality. Keywords: high-density polyethylene feedstock; waste plastic management; techno-economic analysis; aspen hyses; liquid fuels; non-profitability 1. Introduction The generation of fuel and/or energy from waste plastics has significant environmen- tal benefits. However, any process must have a profitable economic incentive, one way or the other, to attract investment and professional acknowledgement. Plastics are one of the cheapest and most versatile materials available in modern so- ciety. For these reasons, a surge in plastic production has been observed in recent years, with 50% of all plastics ever created being made in the last decade and a half [1]. Global production has rapidly increased from the initial introduction of plastics in 1950 [2], where approximately 2 million metric tonnes per annum (MMTPA) of plastics were gen- erated, reaching 407 MMTPA by 2015 [1]. At this time, it is estimated that over 8000 Mt of plastics have been produced, with 6300 Mt being disposed of as wastes [3]. The majority Citation: Zein, S.H.; Grogan, C.T.; Yansaneh, O.Y.; Putranto, A. Pyrolysis of High-Density Polyethylene Waste Plastic to Liquid Fuels—Modelling and Economic Analysis. Processes 2022, 10, 1503. https://doi.org/10.3390/pr10081503 Academic Editor: Young-Cheol Chang Received: 26 June 2022 Accepted: 26 July 2022 Published: 29 July 2022 Publisher’s Note: MDPI stays neu- tral with regard to jurisdictional claims in published maps and institu- tional affiliations. Copyright: © 2022 by the authors. Li- censee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and con- ditions of the Creative Commons At- tribution (CC BY) license (https://cre- ativecommons.org/licenses/by/4.0/).