I just saw an innovative concept from GE: Storage of water below the wind turbine. Details are not very clear, but it looks like, there will be a 40m tall water storage unit below the wind turbine. The tower of the WTG is 138m and it sits on a 40m high water storage unit for a total hub height of 178m. GE is using the 3.4 MW WTG with rotor diameter of 137m. So the total height to tip of blade is 246.5m, which GE claims is the tallest wind turbine. There will be 4 such WTGs in the hybrid park. What is really unique is tight integration with hydro ... storing water under each WTG.
A 16 MW hydro generator sits 200m below the wind turbines; there is also a lake to store the water after it has gone through the hydro-generator. So the concept is when there is excess wind energy, water will be pumped from the lake to the water storage unit below the wind turbine, and when the electricity prices are high hydro power will be generated. An alternative concept may be more important--use of this scheme for secondary frequency response for grid stabilization during ramping and other random events caused by varying WTG output or varying load that would otherwise require expensive ancillary services.
It would be interesting to compare cost of wind-hydro versus wind-battery. Obviously this wind-hydro hybrid requires the stars to line up in terms the right location with good wind, hydrology and contour/elevation, while the wind-battery hybrid does not need any of this. Nevertheless, it would an interesting cost comparison.
For more details see http://nawindpower.com/ge-max-bogl-to-install-huge-wind-turbine-with-pum...