Simultaneous Energy, Fresh Water, and Biogas Production Process Utilizing Solar Thermal and Sewage Sludge

Abstract

Minimizing the detrimental effects of global warming and pollution from fossil fuel consumption is essential to meet the growing demand for energy and fresh water, making it imperative to adopt renewable energy alternatives. The integration of solar energy and biomass in hybrid renewable energy systems will grow in importance. The proposed study introduces a new design that facilitates the simultaneous production of power, biogas, and fresh water in a continuous process. The present research aims to tackle the challenge of utilizing multiple renewable energy sources, such as solar and biomass, to generate power, fuel, and fresh water. To achieve this, a 4-stage multi-effect desalination system will be employed for desalinating seawater. This paper discusses combining hybrid solar and biomass feedstocks to address the challenge of maintaining consistent energy production in renewable solar power plants at night, when there is no sunlight. The challenge at hand involves assessing various factors using ASPEN Plus software, such as solar heat transfer fluid (SHTF), sewage sludge flowrates, biogas production, output waste stream of gasification reactor, power generation, and freshwater production. Additionally, the payback period for this project is approximately 4.8 years, with a net present value (NPV) of around 560 million dollars. By performing a sensitivity analysis, the viability of the designed process and the quality of the resulting products were effectively demonstrated. From the gasification process, an impressive 76.8586 tons per hour of syngas, composed of carbon monoxide and hydrogen, was generated. Additionally, the power output of the system reached 34.547 MW, while simultaneously producing approximately 783 m3/h of fresh water. Due to efficient energy recovery throughout the entire process, only 25 MW of solar power was required. Despite efforts, fresh water production was only operating at a 50% productivity level. To supply the required solar energy during daylight hours, a total of 38,908 square meters of Parabolic trough collector (PTC) was necessary. According to the environmental analysis, the primary concern is the detrimental effect of pollution on human health. Solar collectors and sea water desalination units account for over 95% of the pollution. The revelation showed that combining solar and biomass energy resources could provide a sustainable solution to meet the rising demand for fresh water, electricity, and fuel. © 2025 The Author(s). Energy Science & Engineering published by Society of Chemical Industry and John Wiley & Sons Ltd.