The advent of energy harvesting (EH) technology represents a paradigm shift in the design of communication systems, by enabling the nodes to harvest energy from environmental source, e.g., the sun, the wind, heat, and etc. This presents a tantalizing possibility of perpetual operation. However, typically the harvested energy is sporadic and random in nature. The fundamental energy conservation principle mandates that, at any time instant, the amount of energy an EH node can use is limited by the energy available in its battery. This call for development of new energy management schemes. Our research efforts in this direction are summarized here.