CHEMICAL ENGINEERING TRANSACTIONS VOL. 83, 2021 A publication of The Italian Association of Chemical Engineering Online at www.cetjournal.it Guest Editors: Jeng Shiun Lim, Nor Alafiza Yunus, Jiří Jaromír Klemeš Copyright © 2021, AIDIC Servizi S.r.l. ISBN 978-88-95608-81-5; ISSN 2283-9216 An Optimization Framework for Biochar-based Carbon Management Networks Beatriz A. Belmonte Research Center for the Natural and Applied Sciences, University of Santo Tomas, España Blvd., 1015 Manila, Philippines babelmonte@ust.edu.ph Biochar-based carbon management networks (BCMNs) are systems that are intended to strategically plan carbon sequestration via systematic production and allocation of biochars for long-term storage to agricultural lands and for simultaneous improvement of soil properties. Other significant potential benefit includes supply of clean energy in gaseous (biogas) or liquid (bio-oil) form. However, a challenge still exists in determining the levels of biochar contaminants that the soil can tolerate. This risk implies that adequate planning will be needed to ascertain the suitability of sinks to biochar application in order to lessen the potential for adverse effects on soil. To maximize the potential benefits of biochar, a modeling framework for BCMNs can be developed with the aid of Process Systems Engineering (PSE) techniques so as to ensure that the quality requirements set for the sinks are met. To fill this research gap in the global biochar literature, this work develops an optimization framework for BCMNs by accounting for the relevant and practical aspects of biochar research. Since the decision-maker can consider distinct degree of tolerance for every impurity and can have different preferences regarding the amount of contaminant that can be tolerated in each sink, a unique risk aversion parameter is assigned in each sink-contaminant pair. The parameter represents the extent to which the decision-maker can accept soil contamination level. To demonstrate the applicability of the framework, a representative network is explored, which attains a profit of USD 17,453,810 and a cumulative CO2 sequestration of 876,961.4 t. The results show how the framework can be used to support decision-making for the proper deployment of BCMNs. 1. Introduction Biochar has been a focus of ample research studies in recent years (Zhang et al., 2019). The basis for this considerable interest results from its direct link to climate change mitigation and indirect link to the water- energy-food nexus (Belmonte et al., 2017a). Numerous publications have heralded biochar as a potentially effective carbon sequestration tool due to its recalcitrant carbon fraction that can remain for a few centuries in soil (Aviso et al., 2018). Biochar has been constantly connected to food security due to its ability to sustain soil fertility which in turn results to agricultural productivity (Sri Shalini et al., 2020). Biochar production integrated with energy system was also designed to produce energy products with negative carbon footprint (Belmonte et al., 2019). Biochar can modify the water retention properties of soil (Tomczyk et al., 2020) leading to reduction of water footprint of crop production. Biochar application to soil has the potential to support the sustainable development goals designated by the United Nations (Kamali et al., 2020). The Intergovernmental Panel on Climate Change (IPCC) projected that the atmospheric CO2 concentration would rise to 590 ppm with an average global temperature of 1.9 °C towards the end of 2100 (Zhang et al., 2019). Some distinguished researchers believe that Negative Emissions Technologies (NETs) such as biochar, enhanced weathering, direct air capture (DAC), bioenergy with carbon capture and storage (BECCS), enhancing natural ocean dissolution and direct ocean injection can help achieve the targets of the Paris Agreement (Haszeldine et al., 2018). Biochar has potentially lower impact on land, water use, nutrients, albedo, energy requirement and cost than other NETs (Smith, 2016). Biochar was estimated to reduce emissions at a rate of 130 Gt CO2 eq until 2100 (Woolf et al., 2010). McLaren (2012) estimated the emissions reduction potential of biochar-based Carbon Management Networks (BCMNs) to be 0.9–3.0 Gt-CO2/y. Tan DOI: 10.3303/CET2183028 Paper Received: 28/06/2002; Revised: 01/08/2020; Accepted: 10/08/2002 Please cite this article as: Belmonte B.A., 2021, An Optimization Framework for Biochar-based Carbon Management Networks, Chemical Engineering Transactions, 83, 163-168 DOI:10.3303/CET2183028 163