The seamless and ubiquitous wireless communication anywhere, anytime, anyhow and between anybody and anything is expected to render daily lives easier. This will continue to grow, increasing at the same time, demand on wireless mobile connectivity between people, machines, processes and so on. There is an opinion that this will be achieved by invoking the Fifth Generation (5G) mobile networks. The aim of this paper is to emphasize the road to energy efficiency as one of the obligatory 5G evolution metrics. In connection with this, energy saving approaches together with energy and information flow among base stations is analyzed in the first part of this paper. Secondly, advances in energy efficiency for wireless networks including 5G mobile systems are explained. Corresponding challenges conclude.