Whatever fossil fuel we export will come back to haunt us as CO2, the major greenhouse gas. It would be cheaper in the long run to buy coal at $92/ton for 92% carbon coal, $40/ton for 40% carbon coal etc. than to suffer the catastrophic climate change consequences including heat waves and drought so bad our farmers' crops can't take it leading to massive famines, both here and abroad. It is technically feasible to capture CO2 from ambient air, but at best it might be possible to get that cost down to between $31 and $32/ton on CO2 captured to force feed it either some photosynthetic microbe for liquid bio-fuel or a chemical processing plant for liquid synthetic hydrocarbon fuel, or add another $18 to $19/ton to bring total cost to about $50/ton to compress CO2 to use it as fracking fluid for enhanced geothermal systems. This is way more expensive than generating electricity from renewable energy and buying coal as mineral rights. We might need to do it to recycle CO2 from liquid fuels for transportation, for those parts of transportation that can't easily be electrified. It is also technically feasible to grow edible plants underground in air-conditioned space with LED grow lights, but most likely NOT economically feasible to feed the human population of the world or even the United States that way.