From the Canary Island of La Palma we sail in one day to our last European destination, at least for the foreseeable future: neighbouring island El Hierro. Propelled by a firm and constant northeast trade wind, we sail south and quickly approach the mountainous, smallest of the seven main Canary Islands. When we arrive at the marina of Puerto de Estaca, we can see them: wind turbines. “The reason for our visit!” Floris exclaims enthusiastically.
Renewable Energy Challenge
The next day we welcome former island council member and sustainability expert Javier Morales on board. He tells us that the island is so far away from the mainland, that no electricity cable was ever laid. Instead, a diesel-fired power station was built on the island. “In order to become less dependent on expensive and polluting diesel to generate our electricity, we were looking for a smart, renewable energy solution”, Javier explains. “The preferred source of renewable energy here is wind power, since we have a lot of wind. And wind turbines don’t take a lot of space. That is important, because on our island a lot of space is allocated to nature reserves. Our challenge was to guarantee a constant supply of electricity for the 10,000 islanders, despite the intermittent nature of wind energy.”
A Unique Combination of Wind and Water
Javier describes how they solved it. “We made optimal use of the natural and geological conditions on our island. Besides windy, El Hierro is also mountainous. Therefore, we decided to combine wind power with hydropower. We built five wind turbines with a total capacity of 11.5 MW, as well as two water reservoirs. One at sea level and a second one at an altitude of 700 meters. With energy generated by the wind mills we can pump water to the upper reservoir. We can control how much water we release from the upper reservoir to the lower one. A hydroelectric power station can thus supplement energy needed to meet the island’s needs as well as guarantee a constant supply of electricity.”
In this setup, the upper water reservoir functions as a gigantic battery. Javier tells us proudly that the combined wind and hydro power plant is the first of its kind in the world.