Typically for the company that invented the iPod, the turbine will be different to contemporary designs. According to tech blog AppleInsider, the turbine will convert energy into heat storage rather than directly into electricity.
In its patent application, Apple says the new system will convert the rotational energy from the turbine into heat that will be stored in "low heat capacity" liquid.
AppleInsider's report states:
"In some embodiments, heat is generated from the friction created between blades connected to the rotor shaft and the low-heat-capacity fluid, such as mercury, ethanol or an inert gas, in which they are immersed. Thermal energy is stored in an insulated vessel. A thermally insulating component like a radiator or conductive rod can be used to selectively transfer heat from the low-heat-capacity fluid to the working based on electrical demand. Finally, the working fluid boils and creates steam which rotates a turbine connected to an electric generator."
However, Apple may have some way to go before it changes the energy storage device in the same way the iPhone changed telecommunications.
The application said the new system can reduce costs associated with variations in wind supply. This heavily depends on grid conditions (strong or weak) and wind power capacity as a share of total power plant capacity. In the Netherlands, PhD research concluded that large-scale energy storage will only be necessary if the share of wind power exceeds one third of total grid capacity.
Battery powered systems are expensive and normally restricted to so-called island systems, such as offline turbines serving isolated arctic communities without grid connection in Alaska.
Storage systems typically add substantially to system investment and power generating costs, and energy storage generally reduces overall system efficiency. In hydropower storage systems total efficiency loss of 12 – 20% is not unrealistic.
Recently, large numbers of storage solutions have been proposed, but high costs and efficiency loss continue to hamper a breakthrough of such systems.