Pipe dream, that's a good one Gav!

The biggest cost isn't likely to be in the energy required to separate, compress and pump the CO2 in resevoirs. More significant is the capital cost of the equipment and infrastructure.

However, CO2 needn't be sequestered directly post combustion (or partially pre combustion in the case of gassification tech), as long as it's offset for a long time it'll do. Mineral sequestration is quite permanent and environmentally benign, and doesn't require huge investments in infrastructure compared to CCS. But the status quo is behind CCS. Agrichar can help too but I see that more as an organic soil improvement with the side benefit of a bit of sequestration. Trees and plants are relatively poor carbon sequesters.

One thing I particularly like about Gore's plan is to 'tax what we burn, not what we earn'. That would really sort things out; with people having more income, they can buy more expensive electric vehicles, lowering CO2 emissions and reducing oil problems. The consumer doesn't suffer financially because costs and benefits of this fiscal system to the consumer largely cancel each other out. They will pay the same or less than in the current system of high income tax, low fuel tax.