oa Thermodynamic and Economic Assessment of Integrated Desalination and Power Generation

There have been a number of studies regarding the efficiency of state-of-the-art thermal (Multi-Effect Distillation, MED), power driven (sea water reverse osmosis, SWRO) and hybrid (MED/SWRO) desalination systems. The comparisons between desalination technologies can be made on a number of critical parameters such as (i) cost of produced water, (ii) energy efficiency, (iii) environmental impact, (iv) reliability and (v) footprint. Whilst the reported relative advantages with respect to parameters (iii) through (v) are conclusive, there remain conflicting recommendations with respect to parameters (i) and (ii), partly due to energy pricing assumptions. Furthermore, existing studies work on the implicit assumption that there is demand for surplus power from integrated power generation and desalination systems.

The presented assessments compare the different thermal, power driven and hybrid desalination systems for output (water/power) achieved from identical energy inputs into thermal power and co-generation cycles for different ratios of desired water and power outputs. This eliminates energy and water pricing issues from the analysis and makes the findings applicable to a range of conventional (e.g. natural gas) and renewable (e.g solar) thermal energy sources. A number of simulations studies have been performed to identify the most energy efficient and cost effective desalination technologies for different water and power generation needs. The key parameters such as power and heat requirements and capital expenditures used in the thermodynamic and economic assessments are in line with ranges reported in the literature and existing plant data. Trade-offs between capital intensity and energy efficiency, which are particularly pronounced in thermal technologies, have also been studied. The paper makes clear recommendations as to the preferred desalination technology for a given seawater quality and water and power demand situation. The paper further explores the impact of technological advances in the form of lower capital costs and higher energy efficiency in the two broad classes of (i) power driven, and (ii) thermal desalination technology. All studies have been performed for seawater qualities observed in the Arabian Gulf.