Power: Windmills stage a comeback: ‘Born again’ amid the search for fossil-fuel alternatives, wind-generated electricity now makes technical and economic sense

Compares the following concepts involving vertical-axis wind machines with regard to their suitability for commercial power generation: constant-speed constant-frequency systems (synchronous and induction); and variable-speed constant-frequency systems (field modulated system; double-output induction generator system; a system using an AC commutator generator; and a system employing a synchronous inverter).