Omni Instruments partnered with Glasgow University to deliver a sophisticated temperature monitoring system for an innovative solar pond project situated in Mecca, Saudi Arabia. This crucial initiative, spearheaded by researchers within the Faculty of Mathematical Sciences at Umm Al-Qura University and generously funded by the Science and Technology Unit of the Kingdom of Saudi Arabia, aimed to meticulously map the temperature gradients within the solar pond’s concentrated brine solution. The success of solar ponds as sustainable energy collectors hinges on their ability to establish and maintain distinct temperature layers, trapping solar energy for later use. Accurate and continuous temperature monitoring is therefore paramount to understanding the pond’s efficiency and optimizing its design for practical applications.

Understanding Solar Ponds:

A solar pond is essentially a large-scale thermal energy collector and storage facility that utilizes a body of water with varying salt concentrations to trap solar radiation. Unlike conventional ponds where heated water rises and loses energy to the atmosphere through convection, solar ponds employ a salinity gradient to suppress this heat loss. Typically, a solar pond consists of three distinct layers:

• The Surface Zone: This is a relatively thin layer at the top with low salt concentration. Wind and evaporation can cause mixing within this zone, resulting in a fairly uniform temperature.
• The Insulation Zone: This is the crucial intermediate layer characterised by a significant increase in salt concentration with depth. This salinity gradient creates a density gradient, preventing the warmer, denser water at the bottom from rising to the surface and losing its heat. This zone acts as a transparent insulator, allowing sunlight to penetrate while inhibiting convective heat loss.
• The Storage Zone: This is the bottom layer with the highest salt concentration. It’s here that the absorbed solar energy is trapped and stored as heat. Temperatures in the Storage Zone can reach significantly high levels, making it a potential source for various thermal applications.

The Importance of Temperature Profiling:

For the Saudi Arabian solar pond project, detailed temperature profiling of the concentrated brine was essential for several reasons:

• Efficiency Assessment: Understanding the temperature distribution within each layer, particularly the heat gain and retention in the Lower Storage Zone, is critical for evaluating the overall efficiency of the solar pond as an energy collector.
• Stability Analysis: Maintaining the stability of the Insulation Zone is vital for the long-term performance of the pond. Temperature gradients can influence the salinity gradient, and monitoring these interactions helps prevent mixing and heat loss.
• Optimisation of Design Parameters: The temperature data collected can provide valuable insights into the optimal depth and salinity gradients for maximizing energy absorption and storage under the specific climatic conditions of Mecca.
• Prediction of Energy Output: Accurate temperature profiles allow researchers to predict the amount of thermal energy that can be extracted from the Storage Zone for potential applications such as desalination, power generation, or industrial heating.

Omni Instruments’ role was to provide a robust and reliable temperature monitoring system and controlling a pump to add water to the pond as evaporation lowered the water level, whilst maintaining the salinity levels. The whole system needed to be capable of withstanding the harsh environmental conditions in Saudi Arabia and accurately capturing the temperature variations at different depths within the solar pond. The data gathered by this system would be instrumental in advancing the understanding and practical application of solar pond technology as a sustainable energy solution in the region.