CHAPTER 4: The Use of Artificial Trees

Direct capture of carbon dioxide from ambient air with devices that resemble trees could contribute to a net zero carbon economy and even support a level of negative emissions sufficient to drive the concentration of carbon dioxide in the atmosphere in a matter of decades back down to acceptable levels. Direct air capture adds a new capture method to the carbon capture and storage technology suite. It can work with all storage options and cancel out emissions from any source. Point sources, in the main, would be better off capturing their own emissions instead of releasing them to the atmosphere. Capture from air would likely focus on emissions from the transportation sector. Here, air capture can also support a closed carbon cycle that starts with carbon dioxide from the air and non-fossil energy and produces liquid fuels which, after use, return their carbon back to the atmosphere. Air capture can retrieve carbon dioxide that has been released to the air in the past, and thus reverse emissions and limit their damage to the duration they were allowed to reside in the environment. The ability to reverse emissions adds a new dimension to policy options.