We study the problem of broadcasting in energy constrained stationary wireless ad hoc networks so as to maximize network lifetime. Here, network lifetime implies the number of successive broadcast sessions that can be supported in a given wireless ad hoc network. We assume that each node in the network is equipped with a single omnidirectional antenna and capable of participating in cooperative transmission. We consider three different signal transmission techniques in the physical layer (i) point-to-point, (ii) point-to-multipoint (i.e. multicast) and (iii) multipoint-to-point (i.e. cooperative transmission). We propose a dynamic power allocation scheme for cooperative transmission that takes channel condition and residual battery power information into consideration. Our proposed scheme combines this new power allocation scheme with an energy aware broadcast routing algorithm for maximizing network lifetime. Simulation results show that network lifetime can be significantly improved following our cross layer approach compared to existing noncooperative schemes.