Design and thermodynamic analysis of a novel methanol cogeneration system based on waste energy recovery and water electrolysis, and multi-objective optimization

In response to the challenges of municipal waste storage and transportation in the current era, along with the growth of the green chemical industry, a novel methanol cogeneration system has been designed. The primary objective of this system is to establish a carbon-based, zero-emission energy recovery mechanism that processes municipal solid waste to generate clean methanol energy. This system utilizes 360 tons of municipal solid waste daily for combustion, synthesizing 80 tons of methanol per day using flue gas from combustion and hydrogen derived from water electrolysis. The water electrolysis process demands 27.5 MW of power, achievable through a balance between waste-to-energy and photovoltaic generation, where waste-to-energy combustion compensates for the variability in solar generation. Heating needs can be met by harnessing the waste heat from the production process. Special attention has been given to heat integration among various equipment during the design phase to minimize waste. Regarding performance assessment, the energy and exergy efficiencies of the proposed system are 47.63% and 45.70%, respectively. The system boasts a discounted payback period of 4 years. Over a span of 20 years, the project's net present value (NPV) is estimated at 197,400 k$.