ABSTRACT
The most recent regulations in many industrialized countries allow the connection of small wind turbines—or other renewable energy systems—in parallel with the grid. There are circumstances when it is necessary to store energy—not only electric energy—in order to adapt the wind availability to the user's demand. There are several energy storage techniques, for instance, as compressed air, pumping water to a higher tank or basin, heating water in an insulated tank, as electric or magnetic field. Stationary batteries are mostly employed as backup energy supply in case of blackout for large buildings or critical applications, or as energy storage in places not served by an electric grid. The price of lithium batteries may fall in the future because of scale economies induced by the car manufacturing industry, but for small wind power systems the only current alternatives for designing an off-grid energy storage are two: stationary lead-acid batteries and alkaline Ni–Fe and Ni–Cd batteries.
