![\"Piles](\"https:\/\/renewable-carbon.eu\/news\/media\/2022\/03\/1x-1.jpg\")
Heirloom Carbon Technologies Inc. said Thursday it raised $53 million from investors including Breakthrough Energy Ventures, a clean-technology fund led by Bill Gates, and the Microsoft Climate Innovation Fund.<\/p>\n\n\n\n
As a growing number of companies have set goals to reach net-zero emissions in the coming decades, demand has surged for ways to offset their ongoing pollution. However, experts warn that cheap credits based on avoiding deforestation or building renewable energy projects tend to exaggerate their climate benefits. Technologies that actually remove carbon from the atmosphere can more credibly back the promise of capturing and storing a set amount of greenhouse gas.<\/p>\n\n\n\n
But those technologies are still nascent and often require complex machinery, making them tens of times more expensive than carbon credits from projects that plant trees of build wind farms, which can cost as little as $3 per ton.<\/p>\n\n\n\n
One reason for the high cost is that direct-air capture technology has so far relied on the use of expensive solvents that can separate CO\u2082 from the air, like iron filings to a magnet. Once the gas is bound to the solvent, it needs to be heated to a high temperature to release the CO\u2082, which can be captured, compressed and buried deep underground in rock formations similar to those that hold oil and natural gas.<\/p>\n\n\n\n
Heirloom uses a similar process, without the expensive solvents. The company starts by heating limestone, also known as calcium carbonate, to more than 600\u00b0C in an electric furnace that\u2019s powered by renewable electricity. That\u2019s the most energy-intensive and expensive step. The process releases CO\u2082 \u2014 which is captured \u2014 and the leftover calcium oxide is spread out in hundreds of trays that are stacked 20-feet high and exposed to the air.<\/p>\n\n\n\n
\u201cIt looks like cookies in a baking tray,\u201d said Heirloom Chief Executive Officer Shashank Samala. \u201cWe\u2019re trying to simplify as much as possible.\u201d<\/p>\n\n\n\n
![\"Peering](\"https:\/\/renewable-carbon.eu\/news\/media\/2022\/03\/1x-1-1-1024x768.jpg\")
Over months or years, calcium oxide gets converted back to limestone as it absorbs CO\u2082 from the air. But Heirloom says that by turning the material into a fine power and carefully placing the trays to maintain the right conditions, it can shrink the process down to a week. Once calcium carbonate is created, the cycle is repeated 15 times or so before the material isn\u2019t able to effectively capture CO\u2082.<\/p>\n\n\n\n
Samala declined to provide more details on the company\u2019s approach because some of the tweaks it has made to accelerate the capture process are quite simple and yet to be patented. The engineering work \u201ccould be easily replicated by others, even with a couple of clues,\u201d said Julio Friedmann, chief scientist at Carbon Direct Capital Management LLC, another fund that contributed to Heirloom\u2019s latest investment round.<\/p>\n\n\n\n
Heirloom has so far only tested the different steps in its process individually. The new money will be used to build a pilot plant by next year that will put them all together and attempt to capture a few tons of CO\u2082 every day. Unlike some other direct-air capture startups, Heirloom does not need to overcome basic science challenges, such as whether the capture process can actually work quickly, said Friedmann. The technology is based on peer-reviewed research<\/a> published in 2020.<\/p>\n\n\n\n