Exhaust steam utilization in waste-to-energy strategies: From district heating to desalination

Abstract

This study undertakes a comprehensive comparative analysis of different Municipal Solid Waste incineration systems, specifically targeting their energy recovery efficiencies, while also presenting a pioneering exploration of exhaust steam applications in such systems for desalination. The systems evaluated encompass electricity-only generation, air-cooled condensing steam, water-cooled condensing steam, and exhaust steam utilization for both District Heating (DH) scenarios (I, II, III) and Desalination. An energy balance model is employed to simulate and quantify the energy flows and efficiencies within these systems. The results show a wide variance in energy recovery efficiency, ranging from 11.2% for electricity-only to 66.8% for use of exhaust steam in Desalination. Notably, the DH (I) system, which incorporates heat recovery for district heating, showed a significantly higher energy recovery efficiency (57.5%) than the electricity generation-focused systems. The enhanced DH systems (II and III), which integrate condensing and two-stage extraction mechanisms, further improve energy recovery to 59.4% and 58.3% respectively. A sensitivity analysis, accounting for advancements in district heating systems, revealed a potential efficiency increase of up to 5%. The site assessment underscores the Persian Gulf, East Asia, Island Nations, and the European Mediterranean as prime candidates for WtE-desalination cogeneration, while Australia, South & Southeast Asia, the United States, and the Non-European Mediterranean demonstrate notable potential, each presenting unique attributes and challenges that influence their suitability. The efficiency and appropriateness of these systems are strongly influenced by specific external factors such as waste composition, local demand for energy and water, and geographical location.