They have too much of it. They can import row materiel to aluminum produce it and then send it back to the country from which the materiel came. To produce aluminum takes a lot of energy. On the picture can you see one of the water hydropower stations. The sheep NZ is full of sheep.
Sheep farming is one of the most important industries in New Zealand.
There are more sheep in the country than humans. This is one of the reason way they eat more meat then fish. It's difficult for a farmer to take care of so many animals. They use dogs to get the big herds of animals to the places they want. Often the roads out in the country side is being used for this transportation.