  Seeking for next-generation energy sources that are economic, sustainable
(renewable), clean (environment-friendly), and abundant in earth is crucial
when facing the challenges of energy crisis. There have been numerous studies
exploring the possibility of carbon based materials to be utilized in future
energy applications. In this paper, we introduce T-carbon, which is a
theoretically predicted but recently experimentally synthesized carbon
allotrope, as a promising material for next-generation energy applications. It
is shown that T-carbon can be potentially used in thermoelectrics, hydrogen
storage, lithium ion batteries, \emph{etc}. The challenges, opportunities, and
possible directions for future studies of energy applications of T-carbon are
also addressed. With the development of more environment-friendly technologies,
the promising applications of T-carbon in energy fields would not only produce
scientifically significant impact in related fields but also lead to a number
of industrial and technical applications.
