New Zealand firm Green Zephyr is reportedly developing the world's first energy storing wind and hydro dam hybrid technology.
The system involves stacking small wind turbines in a honeycomb-like structure. The turbines, connected to pumps, then raise water about 90m to a reservoir on top of the structure. This water is then used to drive a generator.
The water is recycled by the system though there are some losses due to evaporation. A typical wind dam would be about 50m wide at the base, narrowing to 18m at the top, with 17 rows of turbines stacked on top of one another. The length of the structure could be 1km or more. The reservoir at the top would be about 10m deep and could store enough water to generate around 12 hours of electricity.
The ideal location for the wind dams would be alongside existing hydro schemes, allowing the same water to be used to generate extra electricity.
A one-eighth scale model of the wind dam is planned at Ardmore Aerodrome, in New Zealand which may be operating by November.