The internet has had a tremendous impact on our routine life. Recent developments in the Internet of Things (IoT) technology have brought several issues to fore. IoT is a new emerging technology in which the electronic devices communicate through the medium of the Internet for remote sensing and control. IoT is not a single technology; rather it is the convergence of heterogeneous technologies pertaining to different engineering domains. Prominent technologies include Radio Frequency IDentification (RFID), Networking and Communication, Wireless Sensor Networks (WSN), Real-Time Systems (RTS), Cloud computing, etc. In establishing communication between devices, IoT exposes to many challenges on account of the diversity of devices, energy, and power constraints, noise, and interference, stringent requirement of timeliness, etc. Though several researchers have attempted addressing these challenges in IoT, more research is still required for the complete transition from internet protocol version 4 (IPv4), developed in 1981 to IPv6, developed in 2008. Researchers need to focus on increasing the address space to cater to unlimited things on our planet, evolving set of standards for uniformity and developing new energy sources for powering every single sensor. Till date, research has focused on evolving design strategies for energy autonomy in electronic devices deployed in IoT, so as to enable self-powering of a device, in absence of DC supply. Present work reviews research on implementable methods of energy autonomy, reported in the recent literature (during 2010 to 2018), so as to identify immediate issues to be addressed and new directions to be explored for enhancing energy autonomy of devices deployed in IoT. The conclusions of the work will be useful for researchers engaged with addressing issues in energy optimization in various domains of IoT. Also, the conclusions will be of interest to business personnel, sponsoring government agencies, agencies for standardization of performance and academicians engaged in the development of IoT.