why enhanced rock weathering is our best hope for gigaton CDR in the next decade

May 2023

Pete Olivier, New Markets at UNDO (so yes, def biased. apply salt now)

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Disclaimer:

Yes, we need to deeply decarbonize for any of this to matter, and yes we need all carbon removal pathways like DAC, OAE, soil carbon, etc to work. we can all win together, and it’s worth repeating, in the most basic terms, climate is a group project; we only win together.)

Here is the vision:

TLDR: four simple and transformational steps

  1. quickly scale up ERW to deliver cheap, permanent carbon removal worldwide by using existing gigaton-scale rock crushing, transportation, and farming infrastructure

  2. collect huge amounts of data and use it to replace chemical fertilizers and farming inputs wherever possible, reducing cost and improving yield

  3. distribute the benefits derived from the carbon market to a wide and diverse set of stakeholders — avoiding climate-exacerbated inequity, and making CDR popular and climate action tangible and positive

  4. leverage this political coalition to develop gigaton-scale direct purchasing programs by governments all over the world, driving money into rural communities, soil health, food resilience, and carbon removal (including ERW, but also the full suite of climate solutions)

Why ERW is going to win:

Let’s pretend you’ve had a few and you’re pitching this idea to a friend at a bar. It’s loud and they want to smoke a cigarette, so you need to hit the explanation in the numbers while you stand outside. You have eight minutes. Here is how you get in and out:

  1. Quickly scale permanent CDR
    1. We need to get billions of tons of carbon out of the carbon cycle. We need trees and soil carbon. I like them as much as you do, but they don’t remove carbon permanently, and they can’t do it at a big enough scale. Unfortunately, most ways that we’ve found of doing permanent removal are expensive and require a lot of infrastructure and energy. ERW stores the carbon it captures permanently, and isn’t novel technology. Natural processes using the same pathways store about half a gigaton of carbon every year.
    2. Scaling up is reasonable because crushing up and driving rock around is something humans do a lot. By weight, it’s probably our largest industry at ~47.5 billion tons every year. We do this all over the world, which means both the infrastructure and talent for doing ERW exist all over the globe. We’re also really good at it, which means it’s practically efficient, meaning we don’t emit much carbon. Our work is 90-95% carbon efficient = for every 10 tons of CO₂ we remove, we emit one.
    3. In order to get crushed rock to weather efficiently, we need to spread it out on lots of land. Luckily, humans also love to farm. By land usage, growing crops is the 2nd largest thing humans do (pasture animals = 🏆), meaning we have ~1.69B hectares where we can drive around fairly easily. In fact, we already do this all the time to spread chemical fertilizer and lime, so we don’t even need new trucks.
    4. Stitching these bits together means we can leverage the world’s largest industries to scale carbon removal. Inserting carbon removal into existing gigaton industries means we can get that scale without unreasonable growth expectations. A gigaton of removals using ERW would represent a 10% increase in the world’s aggregate production - a big year, yes, but fully within the capacity of existing supply chains and sources of talent.
    5. Because we’re leveraging things we’re already good at and do at a huge scale, we can do the work at a relatively low cost. Each ton of carbon doesn’t also have to bear the costs of building out new global supply chains and transportation infrastructure.
  2. Transform ag
    1. Feeding the world is good. And industrial ag, which allows this to happen, is in many ways a modern miracle. Unfortunately, it’s not sustainable. It degrades the soil over time, emits a lot of carbon, and requires a lot of chemical inputs that are either mined from the ground (phosphorous, potassium) or created in processes that release a lot of CO₂. Farmers don’t want to degrade their soil, of course, but they run on the finest of margins, so any attempts to change their operations must fit in the context of a profitable business that maintains or increases yields.
    2. Inconveniently, the cost of chemically-derived farming inputs is spiking, leaving farmers with ever-thinner margins, and in some places, lower yields caused by cost-saving. However, chemical inputs are very well known, meaning that they can be applied in a scientific fashion with predictable impacts on crop yield. This means that farmers expect predictable inputs, but increasingly can’t afford them.
    3. Basalt-based ERW contains many (not all) of the 17 micro and macronutrients that plants need to grow. Initial crop yield studies show positive trends, but we don’t have enough information to be predictive yet. However, the more we scale our work, the more data we generate. With better datasets, we can develop dynamic and broadly applicable models that will show how individual minerals release their component elements, how different plants respond, and how this will affect soil health and crop yields. With luck, scale, hard work, and the application of modern sensing and computing, we should be able to do for ERW what fertilizer companies did over 40 years: generate ag inputs with highly predictive impacts on crop yield.
    4. By replacing inputs that cost a lot and degrade soil with inputs that restore soil health, store carbon, and don’t cost a lot, we can increase margins for farmers, and avoid upstream emissions. This means CDR that can scale without becoming abstract. The benefits are specific - reduced cost and increased income, driving the adoption of practices that are better for the farmer and better for the planet.
    5. Last but not least, a primary cost in farming is the cost of driving around a field (plowing, applying fertilizer, planting, harvesting). However, we pay farmers to drive around their fields when they apply ERW. So, as we get better and more sophisticated, we can turn our work into a physical platform for regenerative ag - enabling low-cost scale for next-gen ag, like applications of nitrogen-fixing bacteria or soil health-promoting fungi.