The trade exists so that the exporters can avoid the costs of properly managing the hazards (lead and cadmium) and simply reap the profits from the valuable material(copper).
The key change was the addition of copper strips to the metamaterial that shields an object from incoming light to create a better material, couple with a slight change in its orientation to solve a problem caused by dividing the metamaterial of the cloaking device into quadrants.
Costs for coal are highly dependent on the cost of gasoline, and the costs for wind are highly dependent on material costs like steel and concrete as wind requires about 10 times the amount of steel, concrete and copper per kWhr than any other energy source.