DESCRIZIONE
A structural duct apparatus includes a cross flow turbine for use in a fluid flow. The turbine has at least one straight vertical aerofoil blade and at least one helical aerofoil blade slanted toward the direction of rotation. Inner and outer walls of the duct apparatus provide an inner diffuser flow passageway that houses turbine power take off modules with the outer surfaces of the duct influencing flow direction so that where there are at least two ducts an open flow barrage is advantageously formed.