The lesson that you can't fight the tide. You can force your own utilities to use only coal, and that'll only make them less competitive. Later you'll have to force them not to buy more affordable power from utilities outside the state, which use renewables. As a result, the cost of living and the cost of doing business increases for everyone in your state, comparatively. You might as well have increased taxes. When the time comes when you're forced to face reality, you regret not having instead used all that extra imposed cost to retrain your workforce and incentivize your industry to move to more promising businesses.