Wireless ad hoc sensor networks are widely used in real world applications. They are used in both civilian and military fields. Since they are resource constrained, they are vulnerable to various kinds of attacks. In this paper, their resources are very valuable for the lifetime of network. The network availability depends on the energy efficiency. Therefore energy depletion attacks on such network are to be addressed. Many solutions came into existence for protecting sensor networks. However, there is room for research in the area of energy depletion attack detection and prevention.