Innovative CSP with a Heat recovery system

An innovative CSP cycle using CO2 blends will be developed together with a heat recovery system to recover the waste heat of the CSP plant and use it to power a desalination plant. The new technology will be tested for 1 year in the pilot site of the existing CSP plant in King Saud University, Riyadh.

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

      Desalination system coupling forward osmosis and membrane distillation

      In parallel, an innovative desalination system coupling forward osmosis and membrane distillation, using a draw solution, will exploit the waste heat recovered from the CSP plant to desalinate seawater, producing freshwater with a low environmental impact and increasing the solar energy exploitation.

      An adaptive coupling cycle to optimize the system

      Finally, the partners will develop an adapted control system to manage the continuous production of freshwater while operating the concentrated solar power plant.



      An innovative power cycle adapted to next generation of CSP plants

      DESOLINATION tackles new generation of CSP power cycles. The working fluid becomes CO2-based and the turbomachinery is adapted to new ranges of temperatures and pressures, to be adapted to future CSP plants. The system will propose an innovative power cycle where supercritical CO2 blends are targeted as the next generation of working fluids.

      The benefits of these innovations are

      1) Adaptable ranges of temperature to match the requirement from the coupling side.

      2) Smaller turbomachinery, i.e. lesser costs

      This new power cycle will be installed in King Saud University and compared with the existing one. Heat recovered via the final heat exchanger will be redirected to power the desalination process.

      An adaptive coupling cycle to optimize the system

      An intermediary cycle will be added between the CSP block and the desalination block to: 1) increase flexibility of use, variation in power need and power supply; 2) deal with transient state, add additional control; 3) assess both, the CO2 blends power cycle and the desalination system independently.

      The adaptive coupling will be used to de-risk the coupling process and make sure that all the steps of the heat recovery process are understood before proceeding with the direct coupling of both CSP and desalination.

      Smart control systems are thus used in the water storage tank to gather data on temperatures and pressures after each type of cycle and test the most appropriate responses on the heat exchangers and fluids.

      After the indirect coupling of CSP and desalination, both processes will be directly linked, removing the smart heat control system and merging the heat exchangers between the power cycle and the draw solution.

      Heat exchangers can take different forms depending on many parameters: temperatures, pressures, chemical properties of the fluids, etc. But they are critical to the heat transfer within the CSP cycles to recover heat from the sun and make the turbine work.

      In DESOLINATION, specific work will be on exchanging heat between the power cycle (air in the existing plant, CO2 in the innovative one) and the desalination draw solution (highly concentrated solution). New Printed Circuit Heat Exchangers (PCHEs) and Printed Fin Heat Exchangers (PFHEs) will thus be produced.

      As a first step, the adaptative storage cycle will provide an easier environment to test heat recovery (exchange will be with water on one side instead of two difficult unknown environments) until both sets of parameters are better known and direct coupling is possible.

      An optimised solar-to-desalination solution

      1. Forward osmosis: seawater is extracted from the sea, water is driven through the membrane by the draw solution and the remaining minerals (brine) are rejected. During DESOLINATION, brine is treated to revalorise its minerals.

      1. Membrane distillation: using the recovered heat, water is separated from the draw solution and goes through the membrane to be collected as freshwater while the draw solution circles back to the beginning of the loop.

      To optimise both processes, the draw solution is tuned to serve several purposes: efficiently attracting water from the sea water, efficiently using the heat recovered from the CSP power cycle and easily being separated from water at the membrane distillation step.