dynamo

 
Pronunciation: /ˈdʌɪnəməʊ/

noun (plural dynamos)

chiefly British
  • a machine for converting mechanical energy into electrical energy, typically by means of rotating coils of copper wire in a magnetic field.
  • informal an extremely energetic person: she was a dynamo in London politics

Origin:

late 19th century: abbreviation of dynamo-electric machine, from Greek dunamis 'power'