Estimates I found (in one article, I linked it somewhere else) put the energy usage of CO2 capture from ambient air at about 2800kwh per ton of CO2, someone els

Estimates I found (in one article, I linked it somewhere else) put the energy usage of CO2 capture from ambient air at about 2800kwh per ton of CO2, someone else calculated one ton of CO2 would produce 376kg of propane. Which is about 5254 kwh. So it would be a significant hit to efficiency, changing it from about 90% to 60%. But that doesn't bring the efficiency to stupidly low levels.