There’s a dirty secret hidden in every wind turbine. They may convert moving air cleanly and efficiently into electricity, but few know much about what they are made of. Much of the material inside wind turbines are the product of brutal encroachments on our natural world.
Each unit requires cement, sand, steel, zinc and aluminum. And tons of copper: for the generator, for the gearbox, for the transformer station and for the endless strands of cable. Around 67 tons of copper can be found in a medium-sized offshore turbine. To extract this amount of copper, miners have to move almost 50,000 tons of earth and rock, around five times the weight of the Eiffel Tower. The ore is shredded, ground, watered and leached. The bottom line: a lot of nature destroyed for a little bit of green power.
A visit to the Los Pelambres mine in northern Chile provides a clear grasp of the dimensions involved. It is home to one of the world’s largest copper deposits, a giant gray crater at an altitude of 3,600 meters (11,800 feet). The earth here is full of metalliferous ore. Just under 2 percent of the world’s copper production comes from this single pit.
Dump trucks, 3,500-horsepower strong, transport multi-ton loads down the terrace roads that line the mine. The boulders are transported by conveyor belt almost 13 kilometers (8 miles) into the valley, where the copper is extracted from the rock. This processing requires huge amounts of electricity and water, a particularly precious commodity in this arid region.
The project is operated by Antofagasta, a London-based Chilean mining corporation that owns 60 percent of the mine. The company built a hydroelectric plant in 2013, almost exclusively to supply electricity to Los Pelambres. Farmers protested against it, and have blamed the project for water shortages in the region.
Now, though, the mine is slated to grow even larger. The company is pumping additional volumes of desalinated seawater from the Pacific coast across the country. Company executives hope this will enable them to continue operating the mine for a few more years. Global demand for copper, after all, is expected to grow immensely, for power cables and electric motors. And for wind turbines.