Perspective of Waste to Energy and Fuel with Negative Emission Potential: Smart Environmental and Techno-economic Analysis

Waste to energy and fuel is an emerging area to deal with waste treatment and realize the circular economy. The issues regarding the disposal of wet waste, especially food waste, are of continuous concern worldwide. The growth of wet waste, which is a manifestation of increased human production and consumption, may imply a high carbon input to the atmosphere. However, it can be converted into bioenergy and biochar, which means a latent economic performance and negative emission potential. Studies on wet-waste conversion technologies have been frequently seen in recent years, whereas few studies have been conducted to summarize, compare, and discuss them. In this review, we evaluate several typical wet-waste conversion technologies (including but not limited to anaerobic digestion, hydrothermal carbonization, incineration, gasification, and pyrolysis) through a literature survey and highlight their carbon emissions and negative emission potential for different categories of wet waste. The review shows that, for the treatment of wet waste, including sewage sludge, food waste, and animal manure, all of the discussed wet-waste conversion technologies were found to be more environmentally favorable than traditional landfilling or composting methods. Anaerobic digestion stands out in terms of both sustainability and commercial maturity. Alongside the assessment of carbon footprints across various wet-waste categories, the technological development and economic performance of the waste-to-energy technologies and the application of artificial intelligence in the field have also been reviewed, aiming to present an objective and comprehensive overview of the advantages and disadvantages of these technologies and to ascribe possible projections of future developments in this domain.