Let me answer this question by offering some history.
The animals are the hard working. They experience many setbacks with respect to the windmill, but they do not let anything stand in their way.
In chapter six, a storm destroyed the windmill, but they started to build it again. In chapter eight, men came in and destroyed the windmill again, but the animals persisted and persevered again. By the end of the book the windmill was built again.However, there is an important detail.
The windmill was not used for electiricty, which would have benefited the animals in the farm. The mill was used to mill corn, so that the pigs could sell it. They chose this option, because they wanted to make money. The profits were too good. Here is what the text says:
The windmill, however, had not after all been used for generating electrical power. It was used for milling corn, and brought in a handsome money profit. The animals were hard at work building yet another windmill;
In addition to this, according to the text, the pigs called the animals to build another windmill.