Energy-Aware geographic routing in wireless ad hoc networks (hereinafter referred to as ad hoc networks) has a significant effect on network performance. It is of great importance for reducing energy consumption, prolonging network lifetime, among other things, thus receiving more and more attentions. This paper provides a comprehensive introduction to the research development on energy-aware geographic routing protocols in ad hoc networks. First, the geographic routing in ad hoc networks is introduced. Next, the formation background, the metrics, the rule of node selection, the research significance and the classifications of energy-aware geographic routing protocols are discussed in detail. Then, some classical energy-aware geographic routing protocols are presented along with multi-angle comparisons and summaries. After that, existing problems are analyzed and open research issues are highlighted. Finally, a summary of this paper is given.