The cost of renewables increase as their fraction of the overall mix increases, i.e. When the fluctuations become harder to be balanced by other sources, and mo

The cost of renewables increase as their fraction of the overall mix increases, i.e. When the fluctuations become harder to be balanced by other sources, and more and more energy storage is needed to handle the fluctuations. Energy storage in that large of a scale is very costly and impractical. In reality what will happen is more and more natural gas usage, which is a bad thing.