Cellular wireless networks are expected to provide high-quality audio and video services while enabling fast and low-cost Internet access to mobile users. The need for green cost-efficient networks is twofold: reduce the service price and preserve the environment. In this work, we discuss the various strategies that help reduce infrastructure costs, power costs, and greenhouse gas (GHG) emissions with no impairments on the quality of network services. These strategies range over a wide area from enhancing the electronics, to developing new energy-aware radio access protocols, to deploying enhanced base stations with tunable capacity. To reduce both capital and operational expenditures, and the GHG footprint, manufacturers propose new compact installation with lightweight antenna systems, very efficient power amplifiers, and efficient hardware and software. The resulting economy can be up to 50 percent or more by reducing the electricity bill, sparing the use of air conditioning, and deploying compact sites that would seldom require maintenance. Recent scientific publications confirm that a very high gain could be achieved by optimizing the use of base stations proactively, and huge additional improvements could be obtained by optimizing power saving mechanisms by leveraging traffic statistics.