Biomass (Food Waste) in Residential Cooling and Heating Sector of the Kingdom of Saudi Arabia (KSA)
Initially, waste management was used to minimize waste volumes and maintain good standards of hygiene. Over the years, the idea of waste management evolved, with principles like waste-to-energy, waste reduction and waste recycling. Besides, due to the high demand and huge need for energy, which is considered one of the most basic aspects for all governments, the considerable amount of waste produced and dumped in landfills underlines the need to use biomass, especially waste, as a source of energy. Waste-to-energy technology (WTET) is a method of recycling waste by transforming its chemical materials to use as a source of energy, like heat and power. One of those technologies is anaerobic digestion (AD), which is used to treat organic waste, for example food waste, to produce biogas, which can be used for producing electricity and heat. AD generates clean and safe energy, which can reduce both the amount of food waste in landfills and the release of greenhouses gases (GHG) while producing energy. The population in Saudi Arabia (KSA) is increasing at 3.4% every year, and is forecasted to reach around 49.9 million in 2030. Also, the KSA 2030 VISION aims to increase the number of visitors for Hajj and Umrah, reaching 6 million and 30 million, respectively. Therefore, the amount of waste will directly increase, and it is predicted to reach around 26.2 × 106 𝑡𝑜𝑛𝑛𝑒𝑠 in 2030, while the food waste, at 13.21 × 106 𝑡𝑜𝑛𝑛𝑒𝑠, will be 50.6% of total waste. The outcomes from AD were estimated in this study under four different scenarios; the scenario without any reduction in the waste has the highest result, producing 52,504.2 TJ as energy potential and 0.58 GW actual power, which can meet 19.3% of the 2030 VISION of producing 3 GW from WTET in 2030. In addition, the amount of power used for cooling (air-conditioning – AC) purposes in general in the KSA is around 60% of the total consumed electricity in the residential sector. Also, the total power consumed by heaters is 0.74 GW in the residential sector. It is possible to produce 77.98% of that power from using AD in the first scenario, whereas from an economic view the AD outcome with the highest value is the first scenario, with total a gross revenue of 8,472.75 Million per year and it is found that using AD has a high potential for cooling and heating purposes. To achieve the sustainability objective of reducing the waste in KSA by 2030, it is recommended to use WTE technology (AD for food waste) with recycling the other types of waste. As a result, there are many advantages of using waste biorefineries in Saudi Arabia, which will help with the unemployment problem, drive R&D in the renewable energy sciences, and reduce both the need to use oil to produce energy and the dumping of waste in landfills; therefore, GHG emissions will decrease.