Wireless Sensor Networks have been implemented in many indoor applications such as offices, hospitals, laboratories for monitoring the parameters such as temperature, humidity etc. Most of the applications have used omnidirectional antennas. In randomly deployed ad hoc wireless sensor networks, this may be useful to achieve coverage and connectivity with unknown neighbors. In case of deterministic deployments such as in case of food grain storages where locations of the sensor nodes are mostly fixed, the main challenges are unstable and vacillating conditions in the godowns during loading and unloading of sacs as well as unpredictable changes in climate. Most of the commercial motes generally use omnidirectional antennas. Energy overheads increase considerably with omnidirectional antennas. Directivity increases energy saving but may be at the cost of redundancy. This paper is mainly focused on the energy advantage in ad hoc wireless sensor networks deployed in large food grain storages and energy overheads required for obtaining certain level of redundancy using directional antennas. Finally, we conclude that energy advantage can be achieved even if we overcome redundancy to certain extent.