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☁️ "Can Enhanced Weathering Be Used to Suck CO2 out of the Atmosphere at Scale?"

Climate 21

Photo by Matthias Heyde | Unsplash
Host: Tom Raftery
Guests: Mel Murphy | Head of Research &
Simon Manley | Head of Carbon | UNDO
Category: ☁️ Carbon | Enhanced Weathering

Podcast’s Essential Bites:

[3:18] MM: "Natural rock weathering is a geological process that takes carbon dioxide from the atmosphere. [...] Naturally, this weathering process locks away billions of tons of CO2 over geological timescales. And so enhanced weathering is simply speeding up this process."

[3:38] MM: "Carbon dioxide dissolves into rain water, and this forms a dilute acid, which reacts with the rocks. [...] We're working with basalt. As this basalt gradually breaks down, it releases macronutrients and micronutrients, including bicarbonate, which is another form of carbon. This bicarbonate moves through the ecosystem, where it ultimately ends up [in] the ocean, permanently removing CO2 as a solid carbonate mineral. [...] We're spreading crushed up basalt rock onto agricultural land or urban soils, where this weathering process is further enhanced by the role of plants and microbes, and speeding up this weathering process to remove carbon dioxide from the atmosphere."

[4:38] MM: "As the rock breaks down, it releases [...] positively charged ions such as calcium and magnesium. And the CO2 in the atmosphere forms carbonic acid, which when it dissolves the rock forms a molecule called bicarbonate. And so this is one of the forms of removal of CO2 as this aqueous form of bicarbonate that moves through the Earth's system, and ultimately is precipitated in the oceans."

[8:37] MM: "A given basalt contains fast weathering minerals, slow weathering minerals and each of these minerals have a different capacity to sequester carbon. This is primarily based on how much calcium and magnesium these minerals contain, which can then be coupled with the atmospheric CO2. [...] We see that if we spread about four tons of rock, we sequester about one ton of CO2."

[11:14] MM: "In the ocean, the residence time of bicarbonate is of the order of about 10,000 years. And then the precipitation of carbonate is effectively locked up for geologic timescales. So we consider the permanence of removal of the order of thousands to hundreds of thousands of years for enhanced weathering."

[12:03] MM: "There's a recent study that's just come out in Nature that suggests that enhanced weathering by 2050 can account for up to 45% of the United Kingdom's emissions targets towards achieving net zero. And they've provided an estimate that enhanced weathering by that time period can sequester [...] 6 to 30 megatons of CO2 per year [...] just in the UK alone."

[26:16] TM: "We have an ambition to be the first company in the world to remove a billion tonnes of carbon dioxide from the atmosphere."

[26:40] TM: "One of the advantages of enhanced weathering, unlike some other carbon removal technologies, is there are relatively low barriers to implementation. You don't need to use technology that perhaps hasn't been invented yet. You aren't looking at high capex in order to get projects implemented. It's all about operational scale up, operational capabilities, and capacity and obviously having the skills to convert physical activities into carbon credits that you can sell to generate revenue."

Rating: ☁️☁️☁️☁️

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🗓️ 10/12/2022
✅ Time saved: 28 min