Information and communications technology (ICT) is expected to play a major role in reducing worldwide energy requirements by optimizing energy generation, transportation, and consumption. Recent research, however, also reveals staggering facts about how ICT is becoming a major component of the energy consumption budget. Some projections indicate that next-generation Internet applications will require electricity in amounts that can't be generated or transported to major metropolitan areas. This special issue provides a snapshot of ongoing efforts toward a global solution to these urgent challenges that will lead, in the end, to a new energy-efficient and sustainable Internet.