POTENTIAL OF WASTE-TO-ENERGY TECHNOLOGIES IN SAUDI ARABIA – IMPACT OF INCREASED POPULATION, HAJJ AND UMRAH, AND GLOBAL WASTE REDUCTION TRENDS IN 2030

Abstract

Municipal Solid Waste (MSW) Management is an ever-present environmental issue in many developing nations, including the Kingdom of Saudi Arabia (KSA), where each year millions of Muslims across the world visit the Holy City of Makkah to perform the Hajj pilgrimage and Umrah. The aim of this study was to determine the most suitable Waste-to-Energy (WTE) technologies for the MSW generated by KSA, Makkah, Hajj and Umrah. The WTE outcomes of energy, power and economic savings produced from the selected technologies were predicted for 2030, taking into account the increased targets for Hajj pilgrims and Umrah visitors as part of KSA’s Vision 2030 plan. Furthermore, the impact of potential reduction policies to meet the UN sustainability development goals (SDGs) for waste reduction were investigated and four scenarios were developed: Current practice scenario (no reduction), and reduction scenarios: 50% food and plastic, 50% food only and 50% plastic only. Anaerobic Digestion (AD) and pyrolysis technology were found most suitable for treating the food and plastic waste components from MSW separately. Increases in the population growth of KSA and Makkah by 2030 and the increased numbers of Hajj pilgrims and Umrah visitors due to KSA’s Vision 2030 plan resulted in increased waste generation and increased WTE outcomes. Although the targeted visitor/pilgrim numbers for 2030 were greater than the local population of Makkah residents in 2030, the waste generated by the tourists was less than the waste from Makkah residents, due to the short duration of Umrah and Hajj. Policies that would result in the reduction of waste in 2030 would result in reduced WTE outcomes, where the highest WTE outcomes could be obtained from the current practice scenario and the lowest WTE outcomes obtained from the scenario with 50% reduction of both food and plastic. KSA gave the highest WTE outcomes followed by Makkah city, Umrah and Hajj. For KSA, the highest WTE outcomes were savings of 13,922 million SAR (3,711 million USD) and total energy of 202,472 TJ resulting in 2.15 GW that could subsidize the future KSA electricity demand gap. AD of food waste typically had higher economic savings from landfill diversion of food waste, for cases where food waste was the major type of waste, however the savings from electricity production from biogas were relatively small; pyrolysis of plastic waste resulted in equal savings from landfill diversion of plastic waste and electricity savings. WTE outcomes for Umrah and Hajj using the Vision 2030 targets for visitors were approximately double those achieved with normal growth to 2030, thus more energy and economic benefits from WTE technologies could be obtained with the Vision 2030 plan. In relation to Makkah city, the food and plastic waste from Umrah and Hajj events in 2030 could contribute approximately half of the corresponding WTE outcomes for Makkah alone. Therefore, if added to the WTE outcomes for Makkah, the city would have a total energy of 18,018 TJ available from WTE technologies, which could be transformed to 192 MW (0.2 GW) of power capacity to subsidize the Makkah electricity grid and reduce the power gap of Makkah city by 12%. It is suggested that recycling, along with WTE technology, could help the kingdom to reach its sustainability goal of reducing the amount of waste by 2030 in tandem with the UN’s SDGs