Underground coal gasification is like cooking coal in a secret underground kitchen. Coal is a type of rock that can be burned to make heat, but instead of burning it on the surface of the ground, we take it to a secret underground kitchen that only a few people can enter.
Once there, we heat the coal really carefully until it starts to give off special gases. These gases are a bit like the ones we use in our kitchens to cook our food, but they are much, much hotter. These gases are also really good at making power, like electricity, that we can use to make our homes and cities run.
The special thing about underground coal gasification is that we don't have to dig up all the coal and take it to the surface. We can just leave it where it is and cook it underground. This makes it much easier and safer for us to get the power that we need.
But, we also have to be careful when we do this because we don't want to hurt the environment around us. Sometimes, if we are not careful, it can cause pollution and harm the plants and animals that live near the underground kitchen. So, we have to be very, very careful and make sure everything is done right.