Galaxy Express 999: Journey with Energy Beyond Space and Time S01 E04 Planet Ena

Maetel and Tetsuro reach a planet called Ena. Maetel is very quiet, so much so that Tetsuro notices it. A volcano begins to erupt and a scientist saves the two. The scientist takes them to the power plant he works for. He begins to teach Tetsuro about the hi-tech plant. He then mentions the key energy-yielding element Enenium.