LOW-COST STORAGE: PAIRING WIND WITH PUMPED STORAGE HYDRO During times of abundant wind, El Hierro’s immediate electricity needs are met by wind generation, and excess electricity is used to pump water up to a large storage lake. When the wind dies down and can’t meet the electricity needs of the community, the water is released and hydropowered turbines supply the needed power. The island includes a location ideal for this type of energy storage: an extinct volcano crater where water can be pumped to a height of 700 meters. While this arrangement doesn’t suit all locations, El Hierro is demonstrating the success of pairing these two renewable options. The size of the renewable energy system— including the water storage location, the electricity-generating pumps used when the water is released, and the wind farm—was determined based on the projected electricity demand in 2030. This ensures that the system can continue to provide renewable electricity to the island and its residents in the years to come.
When wind production exceeds demand, excess energy will pump water from a reservoir at the bottom of a volcanic cone to another reservoir at the top of the volcano 700 meters above sea level. The upper reservoir stores over 132 million gallons of water. The stored water acts as a battery. When demand rises and there is not enough wind power, the water will be released to four hydroelectric turbines with a total capacity of 11 MW.
El Hierro, Santa Cruz de Tenerife, Spain