A collection of 'branch' carbon dioxide collectors, or scrubbers, bunched together and displayed in a small box, designed by Professor Klaus Lackner whilst working for research company Global Research Technologies run by Allen Wright, Tucson, Arizona, USA, c.2008. This item was an expermental prototype technology for direct air capture (DAC), or the removal of carbon dioxide from the air at normal atmospheric concentrations.

Lackner is one of a small number of scientists who had championed DAC during the 1990s and 2000s. When he began developing prototype carbon collectors like this one, most people viewed carbon capture as science fiction, considered too complex to be economically feasible. By the early 2020s, many considered that there is no practical way in which the Earth’s temperature can be kept below 1.5 degrees without carbon capture technologies.

This item is a test sample intended to be used for the mechanical tree’s collector branches or ‘leaves’. They are contained bunched within a small plastic box, with the leaves themselves made from a sorbent-impregnated polypropylene. The sorbent is an ion exchange resin called Dowex marathon A, which binds with carbon dioxide as a bicarbonate when dry. When wet, a carbonate ion replaces two bicarbonate ions, resulting in a release of carbon dioxide. This reversible reaction is central to the mechanical tree concept.

This prototype was made whilst Lackner was a consulting partner to Wright at the company Global Research Technologies. When both men moved to Columbia State University in New York City c.2008 they took this prototype with them. They continued to collaborate on DAC technologies at Columbia and then at Arizona State University, Tempe, between 2015 and 2022.