I think the important part is that widespread adoption of this would reduce the amount of new CO2 emitted into the atmosphere. Even if it was more expensive to

I think the important part is that widespread adoption of this would reduce the amount of new CO2 emitted into the atmosphere. Even if it was more expensive to produce than extracting oil from the ground (itself a process which is becoming more and more expensive, see tar sands), states could mandate that an increasing share of all gasoline sold be made from this process.