A biogas-steam combined cycle for sustainable development of industrial-scale water-power hybrid microgrids: design and optimal scheduling

Lack of sufficient pure water resources and energy crises are two important issues in summer, especially for remote communities located in tropical zones. Electricity is used for seawater desalination, and power generation units need freshwater for energy extraction, conversion, transportation, and distribution. The design and operation of renewable energy sources based on water-energy hybrid grids therefore reduce on-peak electricity demand, potable water scarcity, and pollutant emissions, significantly. This paper proposes a combined cycle for water and power production and investigates its performance under different ambient air temperatures and various load levels. First, biogas is employed to fuel a gas turbine electricity generation process. Then, its waste heat is utilized in a steam turbine heat-and-power extraction cycle. This heating flow is used in a water-heater air-cooler desalination process. A non-linear optimization problem is developed under engineering equation solver (EES) and generalized algebraic modeling system (GAMS) with the aim of finding the near-optimal operating points of the proposed industrial-scale co-generation system, considering its technical constraints and changes of fresh water and power demands during a 24 h operating period. This stand-alone microgrid is able to produce 2.8 L of drinking water per second and 5.8 MW of electricity for large industrial sectors with a minimum efficiency of 37%. Replacing natural gas with biofuels in the water-power nexus contributes most to emissions mitigation, peak electrical-demand reduction, and sustainable water treatment. (c) 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

Automated summary

This study proposes a combined cycle for water and power production to address the lack of sufficient pure water resources and energy crises in remote tropical communities during summer. Adopting a novel co-generation system can significantly reduce peak electricity demand and pollutant emissions, improving energy efficiency.