This is a great conversation... I'm interested to know about their carbon offset accounting system though. Both companies offer carbon offsetting. CarbonCure offers offsets for $165/ton and it looks like Heirloom only offers to big buyers by request, so I can't see their pricing. Is it possible that a ton of carbon is getting sold twice here? I'm sure that they are tracking this.

But if Heirloom is not achieving any permanent storage, it's not clear to me what you get for your Heirloom carbon credit.

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David, I don't Twitter, and you apparently don't actually monitor Mastodon, so I'll hope that this comment is flagged for you. In response to your Twitter request for topics, can you dig up anything on Pumped-Hydro storage? Not a technologically-growing field, maybe, but it sure has possibilities in a world that needs a lot more storage.

In particular, I couldn't help note that Alberta had a very bad couple of hundred hours around the last winter solstice: heavy cloud and sun peaking at only 15 degrees over the horizon, only up for 8 hours/day, the temperature was -31C, and the wind died. For days. 96% gas-powered for 4 million people. They have little hydro.

What Alberta has a lot of, on the western side, is a lot of elevation right next to river valleys through the Rockies. Unless Form Energy is able to beat that $20/kWh target of theirs, pumped-hydro will certainly be an option for those calm winter days on the prairies.

Sorry to be off-topic on your concrete story, which was very good - but you could look into the "self-healing" concrete experiments? Those formulations keep absorbing CO2 throughout their life! Just google "self-healing concrete" - the announcement generated some coverage.

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Toward the end of the podcast, one of the answers to "What would help?" was to create a compliance market to drive demand for carbon removal. I thought you might be interested to know that, here in CA, we are attempting to do that this year with a new bill, SB 308. There is a summary of the bill here: https://drive.google.com/file/d/1HzhcnqX7L_oPAe5TIL3CyOB_8MOuVwBD/view?usp=share_link It would establish clear rules about what should count (durability, measurement & verification, lifecycle accounting, etc.) and then require emitters to purchase carbon removal in amounts equal to a percentage of their GHG emissions each year, starting with low percentages and ramping up to 100% by 2045.

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Fascinating episode.

I do wonder about the viability of Heirloom's process compared to Climeworks. In both cases, there is a cyclic process where the capture material is heated to release concentrated CO2 and then reused. However, while Heirloom needs to heat a kiln to roughly 900 degrees Celsius, Climeworks requires far, far lower temperatures of about 100 degrees Celsius.

Climeworks could therefore potentially use fairly low-grade heat resources such as industrial waste heat or geothermal heat, or in the foreseeable future use high-temperature heat pumps. Heirloom is going to have to use electric arc furnaces (or hydrogen, but I think we're all agreed that would be inefficient and unlikely).

The market will ultimately sort this one out but I'm curious what others think.

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It sounds great, please let's just roll it out.

One thing that I didn't get the "how" for is the "permanent sequestration" piece. At some point it was even mentioned that when the concrete is broken up the CO2 stays in there... Really, so even through the recycling process of these buildings/infrastructure they're able to ensure the CO2 doesn't escape? I mean I am obviously no chemist but that seems to need some explanation? Couldn't find that on CarbonCure's website either. :/

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I was really impressed with this interview, Dave. Heirloom and CarbonCure sound like they will accelerate the CO2 air removal process geometrically. The process starts out with lime (CaC03) and takes all the carbon off of it, and then it readily even wants more CO2 to combine with it. At some point, H2O is added to make calcium hydroxide and the end result is that Heirloom can give all of its chemically procured carbon to CarbonCure and sequester a billion tons of CO2/yr. This is one more thing that can halt climate change in its tracks.

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