A wireless sensor network (WSN) consists of a large number of sensor nodes which are deployed over an area to perform local computations based on information gathered from the surroundings. Each node in the network is equipped with a battery, but it is almost very difficult to change or recharge batteries; hence, maximizing the lifetime of the network through minimizing the energy is an important challenge in WSN. Energy conservation in WSN can be accomplished by different approaches. Our approach is a combination of two methods: 1) utilizing the low-power stand-by mode supported by the wireless devices. 2) adjusting the transmission range on each node. In this paper, we present an energy-conservating solution based on cellular automata. The main objective of this solution is to reserve batteries which is gained through dynamical adjusting the transmission range and switching between operational states of the sensor nodes in the network. We have compared our solution with a certain cellular automata based technique which has recently been proposed through simulation. This comparison examines both techniques in residual energy, coverage, active nodes, fragmentation and connectivity aspects.