Editing IPCC:AR6/WGIII/Chapter-6 (section)

==== 6.4.2.10 Waste-to-Energy ====

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Waste-to-energy (WTE) is a strategy to recoverenergy from waste in a form of consumable heat, electricity, or fuel ( [[#Zhao--2016|Zhao et al. 2016]] ). Thermal (incineration, gasification, and pyrolysis) and biological (anaerobic digestion and landfill gas to energy) technologies are commonly used ( [[#Ahmad--2020|Ahmad et al. 2020]] ). When WTE technologies are equipped with proper air pollution reduction facilities they can contribute to clean electricity production and reduction of GHG emissions. However, if not properly operated, they can exacerbate air quality issues.

In 2019, there were more than 1,200 WTE incineration facilities worldwide, with estimated capacity of 310 million tonnes per year ( [[#UNECE--2020|UNECE 2020]] ). It is estimated that treatment of a minimum of 261 million tonnes/year of waste could produce 283 TWh (1 EJ) of power and heat by 2022 ( [[#Awasthi--2019|Awasthi et al. 2019]] ). Incineration plants can reduce the mass of waste by 70–80% and the volume of waste by 80–90% ( [[#Haraguchi--2019|Haraguchi et al. 2019]] ). Incineration technology can reduce water and soil pollution ( [[#Gu--2019|Gu et al. 2019]] ). However, if not properly handled, dust, and gases such as SO 2 , HCL, HF, NO 2 , and dioxins in the flue gases can harm the environment ( [[#Mutz--2017|Mutz et al. 2017]] ). Anaerobic digestion technology has a positive environmental impact and the ability to reduce GHG emissions ( [[#Ayodele--2018|Ayodele et al. 2018]] ; [[#Cudjoe--2020|Cudjoe et al. 2020]] ). The by-product of the anaerobic digestion process could be used as a nutrient-rich fertiliser for enhancing soil richness for agricultural purposes ( [[#Wainaina--2020|Wainaina et al. 2020]] ). Due to the potential negative impacts on domestic environment and residents’ health, WTE projects such as incineration encounter substantial opposition from the local communities in which they are located ( [[#Baxter--2016|Baxter et al. 2016]] ; [[#Ren--2016|Ren et al. 2016]] ). Therefore, for WTE to be deployed more widely, policies would need to be tailored with specific guidelines focused on mitigating emissions, which may have an adverse effect on the environment.

Depending on the origin of the waste used, the integration of WTE and carbon capture and storage (CCS) could enable waste to be a net-zero or even net negative emissions energy source ( [[#Kearns--2019|Kearns 2019]] ; [[#Wienchol--2020|Wienchol et al. 2020]] ). For example, in Europe only, the integration of CCS with WTE facilities has the potential to capture about 60 to 70 million tonnes of carbon dioxide annually ( [[#Tota--2021|Tota et al. 2021]] ).

Waste-to-energy is an expensive process compared to other energy sources such as fossil fuels and natural gas ( [[#Mohammadi--2020|Mohammadi and Harjunkoski 2020]] ). However, the environmental and economic benefits make its high financial costs justifiable. In 2019, the global WTE market size was valued at USD31 billion, and it is predicted to experience 7.4% annual growth until 2027 ( [[#UNECE--2020|UNECE 2020]] ).

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