Energy is an ability to work, that can be found through energy systems in productive force. The
definition of an energy system includes two steps according to energy conversion and
utilisation. The first step entails the location of primary energy that includes techniques used to
supply energy and its ecological implications. These require the knowledge of its collection or
extraction, transportation and storage. Also important is the type of converters used and the
forms of final energy obtained. The second step of the definition includes the ways in which
energy is conquered through converters and its consumer patterns