The low head energy in for example a river flow is used to provide electrical energy by directing the water through a duct (70), and by inducing air into the duct to create an air flow which is drawn over an air turbine (76) to excite same, and thereby produce electrical energy. The air can be introduced into the flowing water in the duct by a switching arrangement to ensure that no bubbles or pockets of air travel along with the water, which impairs efficiency. The duct may be in the shape of an anti-gravity course (70) to prevent the bubbles from travelling.