Weathering & mineralization
Enhanced Weathering and Mineralization (EW&M) are carbon removal processes that speed up the natural weathering of alkaline materials, releasing cations that capture and convert CO₂ into stable, durable compounds. These compounds can either be stored at the site of mineralization or carried by watersheds and rivers into the ocean.
- Tons contracted
- 330K
- Dollars contracted
- $123.5M
- Contracted companies
- 16
- Est. total capacity
- 1.1–4.4 Gtpa
- Average offtake price
- $368/ton
- Current price range
- $227–1,579/ton
The approach
EW&M approaches primarily vary based on where the weathering occurs and how CO₂ is stored.
| Subpathway | Description | Site | Primary output |
|---|---|---|---|
| Field weathering | Finely ground rock is spread across land, which accelerates weathering by increasing surface area exposed to CO₂- and water-rich soils. This is an end-to-end CDR approach (i.e., includes both a removal and storage component). | Cropland, pastures, forests, or roadsides | Dissolved bicarbonate stored in the ocean |
| Wastewater weathering | Rock is mixed into existing wastewater processing streams, which typically have particularly high concentrations of biogenic CO₂. This is an end-to-end CDR approach. | Wastewater treatment facilities | Dissolved bicarbonate stored in the ocean |
| At-source or surficial mineralization | Material containing alkaline minerals (e.g., mine tailings and industrial wastes) are treated to increase their weathering rates with atmospheric CO₂. This is an end-to-end CDR approach. | Active or orphaned mine sites or industrial facilities (e.g., steel, cement, and lime production sites) | Solid carbonates stored above ground |
| Ex-situ mineralization | Material containing alkaline minerals (e.g., mine tailings and industrial wastes) are treated to increase their weathering rates with external, concentrated, biogenic CO₂ sources. This is a CO₂ storage approach and needs to be paired with a removal technology to be an end-to-end solution. | Active or orphaned mine sites or industrial facilities (e.g., steel, cement, and lime production sites) | Solid carbonates stored above ground |
| In-situ mineralization | CO₂-bearing fluid is injected into alkaline rock deposits in the earth’s subsurface to mineralize the CO₂. This is a CO₂ storage approach and needs to be paired with a removal technology to be an end-to-end solution. | Injection wells above mafic or ultramafic rock deposits | Solid carbonates stored below ground |
EW&M’s role in a CDR portfolio
EW&M offers a promising path to high-volume, low-cost removal by relying on natural weathering cycles. Models suggest that EW&M could provide up to 40% of the global CDR portfolio in 2050, and enough alkaline materials exist from mining waste alone for 1.1 - 4.4 Gtpa of CDR.
EW&M can scale quickly and at a low cost of capital since many approaches do not require massive new infrastructure or technical breakthroughs. While field weathering is often deployed on agricultural land and is best suited for hot, humid climates especially throughout the Global South, surficial and ex-situ mineralization and wastewater weathering can be done at sites around the globe. These factors make EW&M a strong candidate to contribute a large percentage of the global CDR portfolio.
EW&M typically piggybacks off existing industrial or large-scale processes, which could enable it to scale quickly. A number of EW&M approaches fit well within existing systems like agriculture, wastewater treatment, and mining. While this can help EW&M scale and potentially benefit from industrial policy and subsidies, it also requires project developers to work closely with these systems and a wide variety of stakeholders to adjust their standard practices and accommodate CDR, which can slow deployment.
Many EW&M approaches have minimal energy needs. Because the work of capture and storage is primarily done by the alkaline materials, EW&M offers a hedge against energy system uncertainties faced by other pathways (e.g., carbon-free power sourcing and transmission capacity, etc). While there are limited quantities of waste fines that can be used without additional grinding, the energy required is reasonably low for particle sizes down to ~100 μm.
In the near-term, EW&M’s challenges typically stem from potential ecosystem and health risks from metals contamination of soils or the inhalation of fine dust particles during deployment. Following strong procedures to screen feedstocks and adhering to regulations around dust inhalation is important. Field weathering also faces challenges similar to other open-systems pathways, including more difficult measurement, reporting and verification (MRV) and the need for further research on quantification.
EW&M can offer strong co-benefits that generate social and policymaker support. In agriculture, field weathering can reduce fertilizer use and nitrous oxide emissions, control soil pH, and improve crop yields. At-source mineralization could potentially recover critical minerals like lithium and cobalt from alkaline feedstocks and reduce the risk of environmental impacts from untreated mine tailings (e.g., remediating asbestos mine tailings). Wastewater weathering can reduce nitrous oxide emissions and replace carbon-positive hydrated lime or sodium hydroxide for pH control.
Characteristics of great projects
The shape of a great EW&M project will vary depending on the sub-pathway pursued, but all must thoughtfully balance feedstock tradeoffs between reactivity, availability, environmental safety, and the cost of additional processing. A great EW&M project for Frontier:
Creatively accelerates weathering. The best approaches will develop a scalable way to accelerate weathering at a low cost. This could include innovations to acid or thermochemical treatments to lower energy costs, the sourcing of high-reactivity feedstocks that require less milling to reach effective grain sizes, or the utilization of biological accelerants.
Has a robust feedstock sourcing and deployment strategy that balances alkalinity tradeoffs. Projects must have a thoughtful feedstock sourcing strategy to balance cost and efficacy, which depends on a feedstock’s weathering rate, availability, CDR density (how often it can be re-applied before reducing efficiency or causing environmental damage), and concentration of contaminants to ensure reliable MRV and ecosystem safety. For example, for field weathering, while highly-reactive feedstocks like olivine or wollastonite may weather more quickly than basalt, they are generally less widely available, more expensive to mine and/or transport to suitable deployment sites, and may contain some impurities that need to be tracked to ensure accumulation levels remain within safe thresholds.
Excels at logistics (particularly for field weathering). Large, distributed teams will need to work efficiently and effectively across large deployment areas to successfully scale. Logistics challenges include processing and distributing huge quantities of material, conducting quality control on feedstocks, and accurately and reliably measuring CDR.
Has a strong roster of partners. The most promising mineralization companies will secure mining partnerships by easily integrating with existing operations and/or by providing compelling co-benefits such as pile dam stabilization, critical mineral extraction, toxic waste remediation, or co-product production. Field weathering companies will need to work closely with large agricultural producers or enroll large numbers of independent farmers to get access to deployment sites. Similarly, wastewater weathering projects must be able to quickly motivate wastewater treatment plants to shift their current pH management practices.
Has a best-in-class, scientifically rigorous approach to MRV. Many enhanced weathering and mineralization approaches require large deployment areas, and for field weathering, the stored carbon is transported far afield through watersheds to the ocean. This makes MRV particularly difficult for field weathering approaches. Strong MRV will require both measurement-based approaches to quantify the formation of bicarbonate in fields as well as advanced models fed by many redundant field measurements to determine the potential downstream losses of bicarbonate between the deployment site and the ocean. Particularly for field weathering companies, the ability to confidently verify removal and the commitment to publicly share project data are critical for the approach to scale up and come down the cost curve.
Frontier’s EW & Mineralization portfolio
Frontier has purchased from a number of exciting EW&M projects that match these characteristics. Below are examples from our portfolio.
Lithos
- Track
- Offtake - 2023
- Prepurchase - 2022
- R&D - 2022
Lithos spreads superfine crushed basalt on farmlands to capture CO₂ through field weathering. They source their feedstock from existing quarries who produce it in large quantities as a waste by-product. Their core innovation is a novel measurement technique combining soil sampling with high-precision elemental measurements, which allows them to sample at a high frequency with little hardware.
CREW
- Track
- Offtake - 2024
- Prepurchase - 2022
CREW weathers alkaline minerals within the tanks of wastewater treatment plants, which already contain a high concentration of biogenic CO₂. By integrating with existing plants, CREW can reduce the amount of upfront capex needed for new projects and more easily quantify the CO₂ removed through sensors integrated in the inlet and outlet of the plant. With 100,000 wastewater treatment plants worldwide, this approach could be easily scaled to over 500 million tons of CO₂ per year.
Terradot
- Track
- Offtake - 2024
Terradot sources basalt from quarries across southern Brazil and spreads it on nearby farms to weather and remove CO₂. With its warm, humid climate and well-drained clay and sandy soils, Brazil is an ideal geography for field weathering. The deployed basalt also improves degraded soils, taking advantage of government incentives to promote soil restoration and making farmer recruitment easier.
Exterra Carbon Solutions
- Track
- Prepurchase - 2024
Exterra uses a thermochemical process to transform mine waste into fast-dissolving alkaline minerals for carbon removal. Their process cleans up mine sites by eliminating asbestos residues and also extracts low-carbon metals like nickel that can be sold to reduce the cost of removal.
Anvil
- Track
- Prepurchase - 2024
Anvil contacts alkaline minerals with atmospheric CO₂ in a low-energy system that speeds up the mineralization process. The resulting solid carbonate minerals are then stored durably on-site and the removal can be easily measured. The team is targeting a promising, highly reactive feedstock and accelerating its broad use for removal at scale.
Purchase targets
Frontier continues to look for new purchases from EW&M companies that complement our existing portfolio and address gaps that accelerate the field more broadly.
Offtake priorities
We are looking for novel projects that meet our criteria for great EW&M projects, meaningfully beat the key performance metrics in our current portfolio, meet the eligibility criteria listed in the Offtake RFP, and:
- Have a near term trajectory to remove large volumes at low cost
- Integrate with large industries (e.g., mining) to scale rapidly
- Co-locate with alkalinity sources to minimize transport costs and emissions
- Balance potential high energy costs with co-product revenue
- Offer remediation co-benefits to accelerate scale, e.g. reduce mine and/or industrial waste liabilities
Apply for offtake
Prepurchase priorities
Frontier is not currently making new field weathering prepurchases, but we continue to look for earlier-stage mineralization companies with novel, potentially breakthrough approaches that are addressing the following innovation areas:
Remediation and co-benefits
Environmental remediation and co-benefits are critical accelerants to build project support and give back to communities hosting CDR deployments, especially those near existing industrial sites. We’re looking for mineralization projects that help build community and policy support by pairing CDR with environmental remediation and other social co-benefits (e.g., neutralizing asbestos tailings, deacidifying tailing ponds, etc.).
Approaches that enhance passive mineral reactivity
The most effective mineralization approaches will maximize the acceleration of weathering to deliver tons more quickly and at lower cost. We’re looking for strategies to accelerate passive mineralization through mechanical, thermal, (bio)chemical, or other means to liberate alkalinity from feedstock. This could include advances to rock crushing and grinding (i.e., comminution) technologies that lower the energy required to achieve small particle sizes, as well as thermal or (bio)chemical treatments to alkalinity sources that separate or leach reactive alkalinity, such as Ca²⁺ and Mg²⁺ from the host rock. In thermal and electrochemical processes, the efficient recovery and re-use of used chemicals and potential by-products is critical.
Project co-development with large alkalinity sources
Mining, processing, and shipping large quantities of alkalinity to deployment sites all increase a project’s costs, upstream emissions, and time to scale. We’re looking for projects working directly with industrial operations that produce large quantities of alkalinity (e.g., mining, steel, cement, lime, etc.) that will enable quicker scale-up, lower costs of mineralization, and greater overall CDR efficiency.
Synthetic alkalinity
Mined alkalinity can often contain problematic contaminants that must be neutralized or managed to avoid negative ecosystem impacts. Synthetic oxides, hydroxides, and other alkalinity could avoid these problems and serve as clean and efficient feedstocks for mineralization (and ocean alkalinity enhancement). We’re looking for approaches to synthetic alkalinity production that minimize energy and capex investment and effectively manage byproducts (e.g., critical minerals, building aggregates, etc.) and wastes (e.g., CO₂ or HCl acid) during production. Specific alkaline minerals of interest include oxides and hydroxides like MgO and CaO as well as Mg(OH)₂ Ca(OH)₂, NaOH, and KOH.
Additionally, low-cost, carbon free production methods of calcium oxide (CaO) and magnesium oxide (MgO) from limestone could enable outstanding improvements to the efficiency and scale of several CDR approaches such as mineral looping DAC, mineralization, and ocean alkalinity enhancement (i.e., ocean liming). We’re looking for any great approach to generate CO₂-free calcium oxide (CaO) or magnesium oxide (MgO) at lower energy and cost than conventional methods. This could include novel calciner and CO₂ capture designs or no-heat alternatives.
Accelerating in-situ and ex-situ mineralization for CO₂ storage
The near-term capacity of geologic CO₂ storage has been a challenge for many CDR approaches given the limited availability of permitted Class VI wells. We’re looking for novel in-situ and ex-situ mineralization approaches paired with carbon capture (e.g., DAC and BECCS) to diversify storage options and offer a hedge against near-term capacity constraints.
Apply for prepurchase
Pathway resources
Frontier BiCRS resources
Field weathering buyer principles
Field weathering ecosystem rubric
CarbonPlan’s Verification Frameworks