2026-09-19T14:05:11Zhttps://dspace.mit.edu/server/oai/request

oai:dspace.mit.edu:1721.1/1467022022-12-01T03:03:39Zcom_1721.1_7582com_1721.1_7581col_1721.1_131023

Winter V, Amos G. Bessette, Jonathan Tae-Yoon Massachusetts Institute of Technology. Department of Mechanical Engineering 2022-11-30T19:42:18Z 2022-11-30T19:42:18Z 2022-05 2022-06-23T14:09:50.116Z https://hdl.handle.net/1721.1/146702 https://orcid.org/0000-0002-8261-1993 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. S.M. Massachusetts Institute of Technology In Copyright - Educational Use Permitted Copyright MIT http://rightsstatements.org/page/InC-EDU/1.0/ Simple, sustainable, water straight from the sun - batteryless electrodialysis desalination Thesis application/pdf Master Master of Science in Mechanical Engineering Publication unknown unknown <Publication xmlns="https://www.openaire.eu/cerif-profile/1.1/" id="de58efa8-403c-4b9a-9c2e-d46529f43964"> <Type xmlns="https://www.openaire.eu/cerif-profile/vocab/COAR_Publication_Types">http://purl.org/coar/resource_type/c_1843</Type> <Title>Simple, sustainable, water straight from the sun - batteryless electrodialysis desalination</Title> <PublishedIn> <Publication> </Publication> </PublishedIn> <PublicationDate>2022-05</PublicationDate> <Authors> <Author> <DisplayName>Bessette, Jonathan Tae-Yoon</DisplayName> <Affiliation> <OrgUnit> </OrgUnit> </Affiliation> </Author> </Authors> <Editors> </Editors> <Publishers> <Publisher> <DisplayName>Massachusetts Institute of Technology</DisplayName> <OrgUnit /> </Publisher> </Publishers> <License>http://rightsstatements.org/page/InC-EDU/1.0/</License> <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> <Access xmlns="http://purl.org/coar/access_right" > </Access> </Publication>