Renewable energy technologies are being developed to address increasing electrical energy needs, to help reducing the usage of fossil fuels for energy generation and at the same time decrease the dependency on fossil fuels.
This paper presents the bioSTREAMTM tidal stream power generation technology, currently being developed by BioPower Systems Pty Ltd. A prototype device is soon to be built and installed in a tidal stream off Flinders Island, Australia. The device is based on the oscillating hydrofoil principle. The relative motion of the tidal current over the foil section of a hydrofoil induces hydrodynamic lift and drag forces. These forces are due to a pressure difference on the hydrofoil. The tangential component of these forces with respect to a pivoting arm is used to drive hydraulic rams in a reciprocating fashion and to pump high-pressure hydraulic fluid, which is in turn used to drive a variable displacement hydraulic motor coupled to an electrical generator.
This paper describes the tidal stream energy conversion technology and the engineering and design of a full scale prototype device with a rated capacity of 250 kW, followed by the development of time-dependent dynamic simulations and the use of CFD simulations and scale model testing to obtain important device variables and characteristics. The principles of operation, the degree of complexity in optimising the device, and the underlying mathematical model are also introduced and explained. The choice of composite materials in the design led to a strong and lightweight design, which is an important aspect for an oscillating hydrofoil.
A future outlook of the technology is presented, where scaling-up from the prototype capacity to megawatt capacity and farm installations of the devices become important factors.