Its impossible to 'put back in' what we are digging out of the ground. Burning 1 unit of coal generates 2.5 units of C02. We would have to replicate the Azolla

Its impossible to 'put back in' what we are digging out of the ground. Burning 1 unit of coal generates 2.5 units of C02. We would have to replicate the Azolla event or Carboniferous period to meaningfully reduce CO2 concentrations in the atmosphere. We need to abandon coal immediately and electrify all transport. Probably going to need a lot of nuclear and renewable energy along the way with a bit of gas to fill in the troughs. The great side effect will be that cities will be dramatically more pleasant places to live and human health will improve, due to the improvement in air quality. We should also get smart about flexible energy demand, ie. allowing cars and appliances to discharge or charge depending on grid conditions. CO2 carbon might have a market for use inside buildings, but its hard to imagine how we will meaningfully dispose of the excess CO2 (just one human generates 1tonne of CO2 annually), and its certainly cheaper to just spend that money on carbon output reduction.