Optimization of sodium bicarbonate based solar pond for power generation

In the oil and gas industry, managing large quantities of produced water on a daily basis as the production blocks mature over time can be challenging, alarming for an effective and equally efficient treatment system to be embarked. A great solution would be to transform the produced water into a solar pond. Salt-gradient solar ponds (SGSP) are capable of storing large amounts of heat that could be used for producing electricity. Studies relevant to sodium bicarbonate solar ponds and its corresponding low-grade energy harvest are still at a pioneering stage, particularly in Malaysia. Thus, this paper investigates possible techniques and approaches to optimize thermal efficiency of solar ponds, using simulated produced water with high sodium bicarbonate content for power generation. It was determined that the best time to acquire the highest lower convective zone (LCZ) temperature is between 12 to 3 pm, when sun peaks right above the head. Also, addition of 18.8 litres of hydrochloric acid (HCl) had significantly reduced the pH and turbidity level of the pond, removing algae while improving solution clarity and heat storage at LCZ. Utilization of neoprene rubber sheet and black soil as insulators had proven to optimize the solar pond thermal efficiency, yielding highest LCZ temperature of 52.3°C with a maximum temperature difference of 18°C. Besides, the application of thermoelectric generator (TEG) to convert heat energy into sensible power output was explored through simple laboratory-scaled design and set-up, where a total of eight TEG modules were required to produce 0.28W of electricity.