Klaus Lackner has designed an artificial tree to remove carbon dioxide (CO2) from the air using 'leaves' that have proved to be 1,000 times more efficient than the real thing.
In addition, real leaves need sunlight but research has shown that the artificial leaves do not. The surface of the papery leaves is coated with plastic that contains a chemical which takes CO2 out of the air and stores it. To remove the CO2, the leaves are washed with water once a month or as needed. They can then dry naturally in the wind, taking in more CO2.
Lackner calculates that his tree can remove one ton of CO2 a day. Ten million of these trees could remove 3.6 billion tons of CO2 a year - equal to about 10% of our global annual CO2 production.
He suggests that the stores of CO2 could be turned into liquid fuels to power vehicles. And indeed, past research has shown that this is possible. Whether it is economical or not is a different question. Lackner has argued that his trees would cost around $200 for each ton of CO2 removed from the atmosphere and this could drop to $30 a ton as the project becomes bigger. While other people claim this figure is unrealistic (some calculate it at $600 per ton), it is clear that the project will only be economically possible at $30 if oil companies buy the liquid fuels for around $100 per ton, which has yet to be decided.