Can we reduce CO2 through carbon capture and storage?
There are two aspects of the enormous amount of carbon dioxide we produce, namely weight and volume, each of which may be much larger than you think. The fact that a dark black solid (coal) is converted into an invisible, evanescent gas can be deceiving. Because one atom of Carbon, atomic weight 12, is combined with two atoms of Oxygen, atomic weight 16, the resulting Carbon Dioxide is almost four times as heavy as the original solid fuel! The volume increase, solid to gas, is, of course, even worse. At atmospheric pressure the Carbon Dioxide occupies 1,800 times the volume of the original solid fuel. To transport and store such large volumes borders on absurdity. For example, if 3 100-car trains provide fuel to a coal plant each week, it would require 11 such trains to remove the carbon dioxide, if we invested the energy to compress and liquify it.
Of course we could use pipelines instead of trains, but if we try to store the carbon dioxide in natural caverns or exhausted mines, as often proposed, the volumes required are beyond reasonable, and frequent leaks are a certainty. Such leaks can be – and have been – deadly to humans and animals because the heavy gas sinks below the breathable atmosphere.
So much for direct capture. Another possibility is to combine it chemically with other material in some way. There are common minerals that could theoretically serve this purpose, but this requires energy, lots of energy. If we find it necessary to capture CO-2 – and we may – the only energy source dense enough and reliable enough to provide what we will require is nuclear.