That's too big a question but here are the two most vital points.

1. No matter how much the burning process is cleaned up, the result always has to be carbon dioxide. That is the inevitable chemical end point. Releasing carbon dioxide in such quantities changes the composition of the world's atmosphere and causes global warming and probably other harmful changes.

2. The carbon dioxide cannot be sequestered despite claims to the contrary. The amount, by weight, is about three times the amount of coal burned. A bit more than 6 billion tons of coal is burned a year. That makes 20 billion tons of carbon dioxide to sequester. Far more than could conceivably be transported or put anywhere. And, it would have to be kept forever. Not just a few thousand years, but forever. It makes disposing of the tiny amounts of radioactive waste from nuclear power, which decays slowly, look like childsplay.

Because of these points continuing to burn coal would be a disaster.

Yes, I generally view it as a problem. My personal preference is for more nuclear power, but I understand why people are concerned about going in that direction as well. As the years go by, people are betting more and more heavily on solar, so it'll be interesting to see how that plays out in the coming decades.

I think, it is non renewable source of energy.So not great to use.