The point of coal is to make electricity and making sure it's cheap means using every resource you have. So I don't quite see how supporting the reopening of coal plants is not the AfD supporting cheap energy.
Of course, there are geopolitical considerations. Germany thought that it could cut military spending by buying Russian gas, and Poland believes that it needs to buy American gas for protection. But none of them can compete with China.
Of course they can compete with China. China is rather resource poor for such a big country and has to import lots of its fuel. Energy is cheap(ish) in China because it is willing to use all available energy sources without net zero ideology.