I want to kown whether there exsits wind energy water heater which can store wind energy and can be used when you want to anytime.

Nope. But there is a great battery that has been developed in the U.S. i posted the story on my blog enviralment.wordpress.com

You cound store energy for heaint water by using a black body in which you whould have to convert the wind energy into wlectricty and then heat. An example is in a freinds home where there was a multi-ton ingous rock in the basement that was heated up during the day and then the stored heat would radiat at night to provide heat for the house. This is very simplistically stated but I hope gets the basic idea across. Batteries are the main option for storing any energy captured from wind.

Cheers

you could take your existing heater element out of your water heater and replace it with a lower wattage one that would work with a 700 watt wind turbine.

there is a 700 watt heating element on this site

make a wind turbine yourself 700 watt