{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/146702"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/146702","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Simple, sustainable, water straight from the sun - batteryless electrodialysis desalination","abstract":"There is a need for reliable, low maintenance off-grid desalination for drinking water in resource-constrained regions. However, current off-grid desalination systems rely on large solar arrays and battery capacity for sufficient power and energy storage - such systems greatly increase the capital costs, operating costs, complexity and maintenance. Electrodialysis is a flexible technology with significant energy and water efficiency in comparison to other thermal and membrane processes and thus provides significant reduction in solar array capacity; however, it has not been exhibited off-grid without significant energy storage. This work proposes and validates a simple, robust, and maximal water production rate control scheme which enables batteryless off-grid desalination. The control scheme proposed involves cascade control with an outer PID loop tracking power and commanding flow rate, and a coupled inner model based control loop which always produces the maximum allowable current and thus, maximum desalination rate for the real-time power. This control scheme is applicable and adaptable to any continuous power system but can be most advantageous in direct-drive variable power situations, such as with solar panels. The controller is extremely simple, computationally efficient, and robust to implement: it relies on two sensors - a flow meter and a conductivity meter, one equation, and a PID controller. We demonstrate and conduct initial validation of this capability in a field pilot using direct-drive photovoltaic batch electrodialysis. We demonstrate a battery reduction of 99.4% from comparable prior art (20 kwh to 120 wh) on a 2 kwh system at a control speed of 100 milliseconds and utilization of 79% and 91% of total solar energy on two separate days of testing. This control scheme enables significant reduction and even elimination of batteries and is a step towards minimal-maintenance, high production off-grid desalination.","abstract_html":"There is a need for reliable, low maintenance off-grid desalination for drinking water in resource-constrained regions. However, current off-grid desalination systems rely on large solar arrays and battery capacity for sufficient power and energy storage - such systems greatly increase the capital costs, operating costs, complexity and maintenance. Electrodialysis is a flexible technology with significant energy and water efficiency in comparison to other thermal and membrane processes and thus provides significant reduction in solar array capacity; however, it has not been exhibited off-grid without significant energy storage. This work proposes and validates a simple, robust, and maximal water production rate control scheme which enables batteryless off-grid desalination. The control scheme proposed involves cascade control with an outer PID loop tracking power and commanding flow rate, and a coupled inner model based control loop which always produces the maximum allowable current and thus, maximum desalination rate for the real-time power. This control scheme is applicable and adaptable to any continuous power system but can be most advantageous in direct-drive variable power situations, such as with solar panels. The controller is extremely simple, computationally efficient, and robust to implement: it relies on two sensors - a flow meter and a conductivity meter, one equation, and a PID controller. We demonstrate and conduct initial validation of this capability in a field pilot using direct-drive photovoltaic batch electrodialysis. We demonstrate a battery reduction of 99.4% from comparable prior art (20 kwh to 120 wh) on a 2 kwh system at a control speed of 100 milliseconds and utilization of 79% and 91% of total solar energy on two separate days of testing. This control scheme enables significant reduction and even elimination of batteries and is a step towards minimal-maintenance, high production off-grid desalination.","abstract_has_math":false,"creators":["Bessette, Jonathan Tae-Yoon"],"institution":"Massachusetts Institute of Technology","degree_name":"Master","degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. 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However, current off-grid desalination systems rely on large solar arrays and battery capacity for sufficient power and energy storage - such systems greatly increase the capital costs, operating costs, complexity and maintenance. Electrodialysis is a flexible technology with significant energy and water efficiency in comparison to other thermal and membrane processes and thus provides significant reduction in solar array capacity; however, it has not been exhibited off-grid without significant energy storage. This work proposes and validates a simple, robust, and maximal water production rate control scheme which enables batteryless off-grid desalination. The control scheme proposed involves cascade control with an outer PID loop tracking power and commanding flow rate, and a coupled inner model based control loop which always produces the maximum allowable current and thus, maximum desalination rate for the real-time power. This control scheme is applicable and adaptable to any continuous power system but can be most advantageous in direct-drive variable power situations, such as with solar panels. The controller is extremely simple, computationally efficient, and robust to implement: it relies on two sensors - a flow meter and a conductivity meter, one equation, and a PID controller. We demonstrate and conduct initial validation of this capability in a field pilot using direct-drive photovoltaic batch electrodialysis. We demonstrate a battery reduction of 99.4% from comparable prior art (20 kwh to 120 wh) on a 2 kwh system at a control speed of 100 milliseconds and utilization of 79% and 91% of total solar energy on two separate days of testing. This control scheme enables significant reduction and even elimination of batteries and is a step towards minimal-maintenance, high production off-grid desalination."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["S.M."]},{"key":"dc:title","label":"Title","values":["Simple, sustainable, water straight from the sun - batteryless electrodialysis desalination"]}]}],"canonical_facts":{"dc:contributor.advisor":["Winter V, Amos G."],"dc:contributor.department":["Massachusetts Institute of Technology. Department of Mechanical Engineering"],"dc:creator":["Bessette, Jonathan Tae-Yoon"],"dc:date.accessioned":["2022-11-30T19:42:18Z"],"dc:date.available":["2022-11-30T19:42:18Z"],"dc:date.issued":["2022-05"],"dc:description.abstract":["There is a need for reliable, low maintenance off-grid desalination for drinking water in resource-constrained regions. However, current off-grid desalination systems rely on large solar arrays and battery capacity for sufficient power and energy storage - such systems greatly increase the capital costs, operating costs, complexity and maintenance. Electrodialysis is a flexible technology with significant energy and water efficiency in comparison to other thermal and membrane processes and thus provides significant reduction in solar array capacity; however, it has not been exhibited off-grid without significant energy storage. This work proposes and validates a simple, robust, and maximal water production rate control scheme which enables batteryless off-grid desalination. The control scheme proposed involves cascade control with an outer PID loop tracking power and commanding flow rate, and a coupled inner model based control loop which always produces the maximum allowable current and thus, maximum desalination rate for the real-time power. This control scheme is applicable and adaptable to any continuous power system but can be most advantageous in direct-drive variable power situations, such as with solar panels. The controller is extremely simple, computationally efficient, and robust to implement: it relies on two sensors - a flow meter and a conductivity meter, one equation, and a PID controller. We demonstrate and conduct initial validation of this capability in a field pilot using direct-drive photovoltaic batch electrodialysis. We demonstrate a battery reduction of 99.4% from comparable prior art (20 kwh to 120 wh) on a 2 kwh system at a control speed of 100 milliseconds and utilization of 79% and 91% of total solar energy on two separate days of testing. This control scheme enables significant reduction and even elimination of batteries and is a step towards minimal-maintenance, high production off-grid desalination."],"dc:description.degree":["S.M."],"dc:identifier.uri":["https://hdl.handle.net/1721.1/146702"],"dc:publisher":["Massachusetts Institute of Technology"],"dc:rights":["In Copyright - Educational Use Permitted","Copyright MIT"],"dc:rights.uri":["http://rightsstatements.org/page/InC-EDU/1.0/"],"dc:title":["Simple, sustainable, water straight from the sun - batteryless electrodialysis desalination"],"dc:type":["Thesis"],"thesis:degree_name":["Master","Master of Science in Mechanical Engineering"]},"updated_at":"2026-07-22T22:22:19Z"}