During the DESOLINATION project, innovative CO2 blends will be developed to optimise the efficiency of the power cycle and fit the required parameters of temperature and pressure of the power cycle’s turbomachinery. Specific heat exchangers will also be designed to fit the particular materials, temperature and pressure requirements of the cycle. Using the know-how on sCO2 gathered from previous H2020 projects, the different components will be first independently modelled and tested at lab-scale. The resulting methodology will provide optimisation strategies to demonstrate both the higher efficiency of the sCO2 power cycle, as well as the efficient coupling of the power cycle to the desalination system.

The DESOLINATION will focus on optimizing the waste heat recovery of the CSP to drive the draw solution recovery method. Using the inputs from WP2 (CSP thermal cycle optimization for desalination) and 3 (Optimised desalination using CSP heat), the obstacles to the integration of both the solar and desalination independent systems will be talked in WP4, where modelling and optimization studies of the integrated process will be performed.

The integration scheme will ensure that the independently high performing cycles can be efficiently combined to reach high production of pure water and electricity.

Membranes are the centre of all the stages of the desalination process, nanofiltration (NF) pre-treatment, Forward Osmosis (FO) and Membrane Distillation (MD) processes. In DESOLINATION, modelling and small-scale testing activities will target the optimization of all steps of hybrid membrane separations. First, NF membranes will be used to reduce fouling and scaling effect in FO. Then, the FO separation membrane will be fine-tuned to ensure control over high water flux in combination with low reverse flux from the draw to the feed solution and thus maximize the efficiency and use of the osmotic pressure difference between the seawater and the draw solution. Lastly, the MD separation membrane needs to optimize the removal of pure water from the draw solution and must therefore be adapted to the chemical and physical properties of the draw solution designed for thermal heat recovery, as well as to the temperature and pressure conditions required for the VMD recovery process.

The necessary process of draw solution (DS) recovery is a key aspect of the DESOLINATION project, as the waste heat from the CSP power cycle will be used to separate the fresh water from the DS. Indeed, after the forward osmosis step, the draw solution needs to be regenerated and separated from the water. DS regeneration is a costly and energy-intensive process that can be controlled by fine-tuning the CSP recovered waste heat to ensure its optimal use as energy source for this process. This can be achieved by defining specific parameters of the draw solution, to maximize its adaptability to the CSP waste heat energy source.

As the aim of the desalination plant is to extract as much pure water from seawater as possible, one necessary outcome is the obtaining of an extremely concentrated brine. The more efficient the desalination process, the more concentrated the outcoming brine and, therefore, the higher the environmental impact.

To decrease this impact, the DESOLINATION project integrates brine treatment as one of its top priorities. The target is a substantial reduction of the environmental footprint of the brine rejection and the development of a valorization strategy of the extracted materials. The international cooperation with the GCC countries involved in the project will provide EU partners with insightful knowledge of the composition of the local seawater to develop the necessary treatment.

Control systems are important aspects of power generation plants and even more so for integrated systems such as the DESOLINATION final demonstrator. The digital twin of the coupled CSP+D plant developed in DESOLINATION will ensure the integration scheme is in line with the final distributed control system. While the CSP and desalination systems are first independently developed, the integration scheme is key to reach the efficient combination of the final plant. The distributed control system (DCS) will provide a real-time control mechanism for the efficient operation and monitoring of the overall plant. Based on a multilayer control strategy that integrates each component’s individual control and an optimal operation strategy, the DESOLINATION DCS system will manage the complete system and be adapted to the existing and next generation power cycles as well as to the desalination plant.

The tests performed on the demonstrators in KSU will validate that the control system methodology is reliable.

The final demonstrators developed in DESOLINATION will be built and tested. The integration of both existing and next generation CSP cycles will be implemented in the King Saudi University facility to allow testing in a real environment. Two phases of tests (transient-state and long-term) will be run on each cycle and will validate the modelled parameters and the expected energy-efficiency of the demonstrators. The objective of the tests is to validate the integration strategy from the heat recovery system to the draw solution recovery method as well as its adaptability to different power cycles. Moreover, the next generation of power cycle will be validated as an efficient coupling to produce both renewable electricity to the grid and sufficient water production to be competitive with other desalination systems. The LCOE and LCOW of the final systems will be compared to state-of-the-art plants.

Based on the knowledge of GCC partners included in the consortium, the DESOLINATION technology will be tested in the specific environmental conditions of the region, such as the very high TDS ratio seawater of Bahrain, which UOB has experience in studying. This will allow the system to be adapted to local conditions and to increase replicability to other sites in Gulf countries. Moreover, the innovations brought to the power cycle with the integration of CO2 blends and adapted, thus smaller, turbomachinery, as well as the work in the integration scheme optimization, target a strong CAPEX reduction of the plant. The final system will therefore not only be energy-efficient but also more cost-competitive than other solar desalination plants, which provides better conditions for its replicability.

Using ACSP and other local partners of the industrial board’s strong implementation in the region and their expertise in both CSP and desalination plants, the DESOLINATION partners will ensure that a clear line of evolution from the end TRL 6 to TRL 9 will be defined. Indeed, for the system to efficiently tackle the carbon emissions of desalination plants, the objective is to ensure the replicability and market uptake of the final demonstrators. The involvement of strong industrial groups in the consortium will ensure that the DESOLINATION development meets the criteria and requirements for the commercialisation of the system.

This WP deals with the modelling and small-scale testing of the integration process between power cycle and the desalination plant. Starting from the models and design developed in work packages 2 and 3, the optimal operating conditions will be identified, so to maximize the plant efficiency and production. The power cycle efficiency will be above 42% with 0.2m3.h-1 of pure water production. The waste heat recovery system will be tested at lab scale, demonstrating the compatibility and synergies of the two systems. A system control will be developed to guarantee the optimum operation of the system at any operating conditions.

The objective of this work package is conducting the economic, social and environmental analysis of the integrated system in order to assess the impact of the DESOLINATION technology.