A patent application from the computing giant Apple claims to be able to store wind power as heat, and then release it on demand to generate electricity.
Apple doesn't just confine itself to innovation in computer and mobile technology, but also pursues ideas in other areas, such as renewable energy. A patent for a design for "On-Demand Generation of Electricity from Stored Wind Energy" was filed by the company in June 2011, and if it pans out, the new technology could help to even out the supply and demand disparities in wind power.
Because wind speeds aren't constant throughout the day and throughout the year, one of the big hurdles for wind power has been developing efficient and cost-effective storage for the energy being generated by the turbines.
Instead of converting the kinetic energy from the rotation of the blades on the turbine directly into electricity, this design calls for converting the rotational energy into heat, which can then be stored and used to generate electricity on demand.
"During operation, the system uses a set of rotating blades to convert rotational energy from a wind turbine into heat in a low-heat-capacity fluid. Next, the system selectively transfers the heat from the low-heat-capacity fluid to a working fluid. Finally, the system uses the transferred heat in the working fluid to generate electricity." - United States Patent Application #20120326445
The heat generated by the turbine is stored in the "low-heat-capacity" fluid, and can then be transferred to a different ("working") fluid for use in electricity generation. According to Apple Insider, the heat would be generated by the friction between blades on the rotor shaft, and the accumulated thermal energy would be stored in an insulated repository until such time as it is needed. When the system receives a demand for electricity, the heat can be selectively transferred to a "working fluid", which will then create steam to power the turbine of a generator.