> 1. why extract from the air when you can just put a device on the smokestack of an existing coal or natural gas plant? The higher CO2 density of the effluent

> 1. why extract from the air when you can just put a device on the smokestack of an existing coal or natural gas plant? The higher CO2 density of the effluent will make things more efficient. That was my big question, too. Asked and got a response here: https://news.ycombinator.com/item?id=19844578 https://news.ycombinator.com/item?id=19844578