A packed bed for solar energy storage in the form of sensible heat has been investigated using two-phase continuous model. The system contains Quartzite as the filler material and Palm oil as the heat transfer fluid. The aim of this work is to propose an eco-friendly storage system which uses natural concrete and certified sustainable oil for medium temperature thermal storage. Using the developed model, the performance of the Palm oil has been compared with two different synthetic oils which has shown that the Palm oil could efficiently be used as a heat transfer fluid for a working temperature below 300°C