Experts say the technology is especially suitable for low - rank coals like lignites and sub - bituminous coal , which produce less heat when burned due to their high ash content , and are highly polluting . " There are , of course , major concerns about water pollution or land subsidence caused by " cavities created when the coal seams are drilled and burned out , " Winning writes . Advocates say water can be protected by managing pressures in the coal seam , and subsidence can be avoided by choosing a site with strong rock layers . And what about the main concern about coal projects ?

Question: Why is the narrator concerned about using coal ?
Answer: They feel it 's not suitable for fuel .They feel it 's not for extracting energy .They feel it 's not good for the environment .They feel it 's not for energy .