One of the more promising ideas for removing carbon emissions from our air takes a cue from the Earth’s built-in air filters – trees. Arizona State University professor Klaus Lackner has created a “mechanical tree” that promises to be thousands of times more efficient than the leafy CO2 absorbers they mimic. ASU and Silicon Kingdom Holdings, a Dublin-based company, have now partnered to erect 1,200 of the mechanical trees in what could be the largest carbon capture effort on the planet.
Officially named MechanicalTree, the devices are installed in clusters of 12 and are capable of removing 1 metric ton of CO2 per day. The two-year pilot farm is targeting 36,500 metric tons of CO2 per, or the equivalent of nearly 8,000 cars worth of emissions. The mechanical trees themselves are tall columns that contain a stack of sorbent-filled disks. When air makes contact with the disk surfaces, the CO2 gets bound up. Once a tree is “full,” the filters collapse down onto themselves inside the bottom container. The gas is then removed from the filters, purified, processed, and can then be either stored or put to other uses. The filters are reused to capture more CO2.
MechanicalTrees are what’s known as a “direct air capture” technique, meaning it pulls CO2 directly from the atmosphere as opposed to capturing emissions at the source, like power plants and factories. The technology uses the wind to blow air through the system so no additional energy is consumed in the process. Direct air capture methods have traditionally been viewed as prohibitively expensive. According to SKH, the cost of capture using MechanicalTrees is comfortably below $100 per metric ton at scale.
Lackner says that $100 price point is where things get “economically interesting.” As he explains, “You can buy liquid CO2 which is delivered by truck in order to fill fire extinguishers and myriad other things for prices between $100 and $200 a ton.” Lackner believes carbon captured using his technology could bring the cost down to as low as $30 per ton.
SKH has not revealed what they expect the actual cost for building the 1,200-unit MechanicalTree pilot farm will be but intends to eventually deploy full-scale CO2 farms in multiple global locations, each capable of removing 3.8 million metric tons of CO2 annually. The company expects its primary market will be companies and governments looking to offset their emissions.
Major oil companies are actually some of the biggest investors in carbon capture technology as they use it in a process known as enhanced oil recovery, which is the number one use for captured carbon in the world. Canada-based Carbon Engineering, another direct air capture company, has partnered with Occidental to build a facility in the Permian Basin of Texas and New Mexico that would take up to roughly 1 million metric tons of carbon dioxide out of the atmosphere annually.
Other major players in the space include Swiss firm Climeworks, the market leader, alongside Carbon Engineering and Global Thermostat. Climeworks has some pretty big customers, including Coca-Cola HBC Switzerland, which uses the carbon dioxide to make seltzer. Climeworks also sells the gas to Swiss greenhouses where it acts as a sort of fertilizer. (Sources: Forbes, Wall Street Journal, Chamber Biz News, Popular Science)
