Optimal synthesis of negative emissions polygeneration systems with desalination

Treatment of reverse osmosis desalination (ROD) brine has recently been suggested as a means to achieve negative greenhouse gas emissions via indirect ocean capture (IOC) of carbon dioxide. In this paper, a novel scheme that integrates the ROD/IOC process with combined cooling, heating, and power (CCHP) generation is proposed as a new negative emissions polygeneration system (NEPS). A mixed integer linear programming (MILP) model is then developed for the optimal synthesis and operation of such a system. The model uses a multi-period formulation to account for hourly variations in product demand and electricity price. The polygeneration system takes advantage of the flexible operation of the ROD/IOC process to operate as a Power-to-X (PtX) system, without the need for direct electricity storage in batteries. An illustrative case study is solved to demonstrate the model, and sensitivity analysis is performed to assess the effects of techno-economic uncertainties on system performance.