Opportunistically accessing the licensed spectrum of the primary user (PU) by the secondary user (SU) without creating interference in the primary user, this phenomenon increases the usability of existing allocated frequency spectrum and reduces the scarcity of radio band availability, hence only 6% of total allocated spectrum/licensed spectrum are now being fully exploited . The increasing demand of cognitive radio and its application also increase the urge to make energy efficient cognitive radio because it is an emerging technology and to meet the future demand of cognitive radio will target the Adhoc structure of communication where battery consumption is one of the major issues in adhoc/mobile devices. So to develop energy efficient MAC protocol for Cognitive Radio Adhoc Network (CRAN) is now today's need. The proposed technique of opportunistically acquiring radio channel without creating interference in the licensed user activity is taken under consideration and focused as the main idea of this survey. Cognitive Radio (CR) transmit data on free licensed band by sensing and monitoring that there is radio channel available which is not being use by any other user, this approach of transmitting data over media through MAC layer and MAC protocol is an energy efficient approach which is also compatible with the existing system. This will increase the potential deployment of cognitive radios (CR) but the process of spectrum sensing, management, mobility and sharing requires higher energy resources . So this survey will expose the energy efficency of different CR MAC protocol techniques.