|US Patent 6,023,105|
Grid energy storage, or large-scale energy storage, if you prefer. It’s one of the phrases you hear bandied about in discussions of alternative energy, solar and wind power, and other forms of non-continuous energy generation and refers to ways of storing electricity on a large scale within a power grid. The only currently available, fully operational, efficient, and widely used grid storage technology is pumped storage hydroelectricity.
Hydropower produced 31 percent of the total renewable energy consumed in the US in 2010, according to the US Energy Information Agency. Wind produced 11 percent. What would happen if you coupled water and wind energy generation technologies?
Wasfi Youssef (Mamaroneck, NY) obtained patent number 6,023,105, “Hybrid wind-hydro power plant,” on February 8, 2000. The patent is classified as a prime-mover dynamo plant including a fluid-current motor (290/54). There are currently (early January 2012) 749 patents in this innovation space within the patentECO Energy Index.
Claim 1 states:
“A hybrid wind-hydro power plant in which a difference between two water levels is utilized to generate an electrical power, comprising:
a first water reservoir located at a high level;
a second water reservoir located at a low level;
an equipment for pumping water from said second low reservoir to said first high reservoir consisting of: (a) a water pump positioned in said second reservoir for pumping water to said first reservoir, (b) a penstock from said pump to said first reservoir, which has a non-return valve to allow water flow upstream but not downstream, and (c) a windmill with a rotational shaft coupled directly to said water pump to rotate said water pump and act as a prime mover for said water pump;
a hydraulic turbine installed to receive water via penstock from said first reservoir and to discharge said water to said second reservoir and to convert said water's kinetic energy into mechanical energy of turbine rotation;
an electrical generator coupled to said turbine and rotated by said turbine to produce electrical energy.”
Youssef intends that wind-driven pumps lift water from downstream, or the tailwater area of a hydropower station, to upstream, or headwater. An adjustable weir constructed downstream the water pump holds the water discharged from the turbine and creates a pool or lake from which water can be pumped. The weir can be lowered or raised, allowing the water flow can be managed to suit the wind and the hydropower plant operation.
Another application of his invention is at sites where the wind is strong and there are two nearby waterbodies separated in elevation. The wind-driven water pumps lift water from low elevation to high elevation, where it is stored until used by the hydropower plant to generate electricity. In this application, a hydropower plant is needed, but a dam and adjustable weir are not needed.
Any type of windmill can be utilized, although a vertical-axis type is preferred by the inventor to a horizontal-axis windmill. The former requires fewer connecting components and its tower is much smaller than that of the horizontal-axis type. On the other hand, the horizontal-axis type can be built in larger units and can be more efficient.
The world’s largest pumped hydro facility lies in Bath County, VA, and generates 3,003 MW of power for Dominion. In recent years there has been much interest expressed by wind energy developers to create large mountain-top wind farms in that part of Virginia and adjacent West Virginia. Will the Bath County pumped storage station become a water and wind hybrid?