Design of hybrid desalination process using waste heat and cold energy from LNG power plant increasing energy and economic potential

The seawater desalination is considered an energy and cost-intensive procedure and thus, the novel hybrid desalination process, which combines forward osmosis (FO), crystallization, and reverse osmosis (RO), is a promising alternative that can reduce the cost and energy consumption. However, this process still has a drawback in that a significant amount of heat energy is still required to raise the temperature of the draw solution and feed water, and a large amount of cooling energy is required for crystallization. This work designed a novel hybrid desalination process using waste heat and cold energy emitted from liquefied natural gas (LNG) power plants for energy efficient desalination, in a bid to increase economic feasibility. To design the suggested system, a process and mathematical model were developed using the experimental results. The process model recovers waste heat emitted from the natural gas combined cycle (NGCC) and waste cold energy emitted from the LNG regasification process. The economic and energy feasibility of the proposed process and its potential for CO₂ capture and utilization were analyzed. The total annualized cost (TAC) of the proposed process could be reduced by 34% compared with the conventional SWRO by efficiently recovering the waste heat and cold energy. In addition, the proposed process could decrease the specific energy consumption (SEC) by 50% compared with conventional SWRO. Furthermore, if the proposed process is applied to CO₂ capture and utilization, approximately 2,733,602 tons/y of CO₂ can be captured, and the incurred total capital investment (TCI) for the installation of additional processes can be recovered in 2.09 years. Thus, an additional profit of approximately 6,111,677 USD per year can be realized.