Design of a low-cost autonomous seawater measurement buoy to scale and optimize a green-powered desalination plant

Climate change and water scarcity has pushed more countries with direct ocean access to seek desalination solutions to face part of their need for domestic water networks or industrial usage, while conserving coastal ecosystems. Seawater monitoring is crucial in implementing a desalination plant as it ensures the efficiency and sustainability of the desalination process, especially in the case of a plant powered by renewable energy sources. Seawater is the main input of desalination processes and coastal areas are the locations of the release of the salty waste. An autonomous buoy can be used to monitor the seawater parameters which are essential to sizing a desalination plant.

There have been recent developments of autonomous buoy systems for monitoring different water parameters, however lacking in certain aspects. Some of the elements of these buoys include limited range of data transmission, high-cost designs, immobility and limited number and types of sensors. Also, there has been lacking implementation of autonomous buoys used in development of desalination plants. 

The proposed low-cost autonomous buoy is designed and constructed using cost effective materials. It increases the possibility of multiplying the sensor count to have a more accurate data mapping system. The low cost provides the opportunity of having more devices where there is a higher probability of equipment loss due to possible theft or remoteness of travel. The power supply is an oversized solar array with a backup battery and solar charger. An Arduino microcontroller is connected to two probes and a GPS sensor. The data is logged on a SD memory card with data transmitted via the Iridium satellite constellation, consisting of 75 satellites. There are two parts of construction involved in the project: the construction of the outer shell of the buoy and the design of the inner circuitry and components. The project involves multiple steps of experimentation: first in a laboratory/controlled area then deployed in the Seto Inland Sea, Japan. The various steps ensure the data collected by the sensors is reliable, valid, and suitable for scientific research. After this successful implementation, the buoy will be adapted and deployed in the Caribbean Sea surrounding Jamaica.

Initial results show a promising possibility of measuring seawater parameters such as GPS location, salinity, and sea surface temperature for any body of water. Utilizing the span of the Iridium satellite communication system, this ensures that virtually all regions of the Earth can be measured. The sizing of the solar powering components allows for at least 1 year of monitoring in the worst-case scenario and 4-5 years in the best-case scenario. The integration of autonomous buoys in the desalination process enhances efficiency in the plant design stages and reduces potential costs which contributes to the optimization of the desalination system. The environmental integration and the operation of the plant will be improved as a result of the enhanced assessment of the input and waste release conditions.

 

Keywords: Seawater Monitoring, Remote Sensing, Desalination, Autonomous buoy, Autonomous measurements