Carbon Mineralization Needs Greater Policy Support to Reach Carbon Removal Potential

There is strong scientific consensus that along with rapid and deep emissions reductions, the global community will need to actively remove carbon from the atmosphere to reach the climate goals agreed to under the international Paris Agreement on climate change. Within the United States, the government’s long-term strategy to reach net-zero greenhouse gas emissions estimates that the U.S. will need to remove roughly 1 billion metric tons of carbon dioxide per year by 2050, through both technological and nature-based carbon dioxide removal approaches. One such carbon removal approach is carbon mineralization, a naturally occurring process that can be accelerated, where certain minerals within rocks react with and sequester carbon dioxide (CO2).

For carbon mineralization to achieve its carbon removal potential, greater federal support for research, development, and ultimately, deployment is needed. Other carbon dioxide removal technologies, most notably direct air capture, have already received significant funding and support from the 2022 Inflation Reduction Act and 2021 Bipartisan Infrastructure Law. Mineralization and other approaches however have not yet received this same level of policy support. This additional support is especially needed to ensure scale up is done responsibly and minimizes any environmental and health risks.

How Does Carbon Mineralization Work and What Benefits Can It Provide?

Mineralization can be used in a variety of ways for carbon removal, both below and above ground. Pathways involve bringing ambient or concentrated carbon dioxide into contact with certain types of minerals within rock — including mine tailings, some types of industrial waste or rocks specifically accessed for mineralization. Mineralization can also be used as a carbon storage option for CO2 captured elsewhere, through underground injection of CO2 into certain types of rock. It can also sequester CO2 in products, for example in cement and concrete.

With greater public and private investment, scientists estimate carbon mineralization could remove up to 1 gigaton of CO2 from the atmosphere annually by 2035 and 10 gigatons by 2050.

Some types of carbon mineralization may deliver co-benefits like strengthening concrete through the injection and mineralization of CO2 in the material, reducing health hazards by remediating asbestos mine tailings, reducing local ocean acidification and increasing crop productivity through enhanced rock weathering.

Another important co-benefit associated with mineralization is in the mining sector where, in addition to its carbon removal and toxic remediation applications, mineralization can be used to extract valuable critical minerals from mine tailings. Demand for critical minerals like cobalt, nickel and lithium is expected to grow in coming years, with the Biden administration expecting at least 400 to 600 fold growth.

These minerals are key components of electric vehicle batteries and other clean energy technologies and are now required to be increasingly sourced from the U.S. to qualify for tax credits under the Inflation Reduction Act. Researchers have devised ways to economically extract critical minerals from some mine tailings while simultaneously mineralizing captured CO2, providing a pathway for the mining sector to earn revenue while removing carbon and supporting the energy transition. The range of ways mineralization can be done and benefits it can provide — for the climate and otherwise — mean not only that it would benefit from greater policy support, but also that policies needed to scale it up must be customized to its different applications.

What Public Policy Support Does Carbon Mineralization Already Receive?

Today, mineralization benefits from government support that focuses on all types of carbon dioxide removal approaches, but unlike direct air capture, does not have dedicated funding streams. Direct air capture is arguably the front-runner carbon removal technology today, and that is in part because it operates within a closed system, which makes measuring CO2 and tracking environmental impacts relatively easier. This is in comparison to many types of mineralization which involve augmenting and leveraging existing natural cycles, which makes measuring sequestration and monitoring environmental impacts more difficult.

At the same time, it is important to acknowledge that direct air capture and other carbon dioxide removal approaches are not at odds: Different approaches will be suited to different local contexts and will provide different co-benefits. Meeting national and global climate goals will require developing a portfolio of natural and technological approaches recognizing the ultimate scale of removals needed and the tradeoffs associated with each approach. 

Current and Introduced Federal Funding Opportunities Carbon Mineralization Is Eligible For

What Additional Policy Support Is Needed to Scale Up Carbon Mineralization?

For carbon mineralization to be a viable option for large-scale removal, it will need greater focused support from early research to deployment, including:

Increased government funding for research and development: Public research and development funding is needed to support early-stage technologies, where the private sector is less willing to take risks. Different mineralization approaches are at different stages of development and require public funding to reduce uncertainties related to resource mapping of mineral availability; acceleration of reaction rates; ecosystem impacts; and measurement, reporting and verification. Different research questions are relevant to different types of mineralization. For example:

• Mineralization below ground: Although CO2 is already being injected into the ground for permanent sequestration through mineralization in basalt and ultramafic rocks (e.g., Wallula project in Washington and Carbfix project in Iceland), further research is needed to better understand underground reactions, as well as the rate and extent to which CO2 is mineralized. This is also crucial to better understand and limit the potential chemical contamination of nearby aquifers and surface waters, as well as the risk of induced seismicity.  
• Mineralization above ground: Research is needed in several areas including better understanding the factors that can accelerate mineralization reaction times both for mine tailings and addition of alkaline material to crop fields and the ocean, as well as potential ecosystem and environmental impacts. Further research is also needed to better understand how to treat alkaline mine tailings and industrial waste most effectively through mineralization, to reduce the health and environmental hazards they present.

Funding for demonstration projects: Mineralization approaches will require demonstration projects at different scales to resolve uncertainties that can’t be addressed in a lab setting, including testing different materials and application methods in different environments and geographies. Government grants, loan guarantees or investment tax credits are options that can cover a portion of the capital costs of a project.

Deployment support: While mineralization projects may be able to attract private investment when they are closer to commercialization — due to co-benefits like increased crop productivity and reducing ocean acidification — the carbon removal that mineralization provides is still a public good that governments have a role to support, at least in the near term. Deployment support can include:   

• Government procurement: This includes direct purchases of carbon removal through carbon mineralization approaches, as is proposed in the Federal Carbon Dioxide Removal Leadership Act and the CREST Act. Mineralization can also be supported through Buy Clean policies, which set limits on embodied carbon in building materials like cement and concrete. Mineralized concrete can provide lower lifecycle greenhouse gas impacts compared to conventional concrete, particularly if the CO2 is sourced from direct air capture. 
• Production tax credit: This provides funding for each relevant unit of production. The current 45Q tax credit is a production tax credit for carbon sequestration. It provides $130 per metric ton of CO2 (tCO2) from direct air capture sequestered permanently in products and $60/tCO2 captured at a point source and used in products, such as cement or concrete.
  • Above ground mineralization: Today, 45Q supports capture of CO2 via direct air capture or point source carbon capture, utilization, and storage, so mineralization techniques that capture and sequester CO2, such as spreading alkaline minerals on agricultural soil, are not eligible for the credit. Mineralization would benefit from an expanded 45Q or an analogous type of deployment support.
  • Below ground mineralization: The 45Q tax credit could be enhanced to make clear that in-situ mineralization is eligible as a form of secure geologic storage.
• Regulatory accommodations: Federal, state and local rules on land use could be amended to ease permitting for mineralization demonstrations or practices. Enhanced rock weathering, for example, may need special permission when conducted on federal land if it is not deemed a “casual use” project. Similarly, alkaline feedstocks could be included as soil amendments under conservation standards as they can increase soil carbon content and agricultural productivity.

Mandates: Governments can go beyond incentives to set regulations that advance mineralization. Governments can require companies with alkaline mine or industrial waste to take steps to leverage it for carbon removal. In terms of using mineralization as a way to reduce embodied carbon in building materials, low-carbon product standards go a step further than Buy Clean and set a carbon intensity threshold for concrete use in a certain jurisdiction. Mineralization would be one way to reduce emissions associated with concrete.

What Policy Support Can Help Ensure that Mineralization Is Scaled-up Responsibly?

For carbon mineralization to scale up responsibly, additional types of government support and action are needed beyond supporting technology development. These include improvements to measurement, reporting and verification and regulations to ensure safe handling of hazardous materials.

Measurement, Reporting and Verification: There are two main challenges, the ability to measure carbon removal associated with mineralization approaches, and the development of consistent, robust standards and protocols to codify this process. Measuring and monitoring the amount of carbon that has been removed through open-system approaches, like enhanced rock weathering, is more challenging than for closed-system approaches, like ex-situ mineralization, where CO2 can be directly measured. Because these approaches are still in development, there is both variability in and scarcity of measurement, reporting and verification protocols for mineralization.

Standardization is crucial to allow for comparison across projects and to hold project developers accountable for their removal claims. Federal carbon removal procurement, included in the 2023 fiscal year appropriations, points to an increasing role for the government in determining what counts as robust measurement, reporting and verification that’s eligible for procurement. Policy support is needed to improve measurement, reporting and verification for various carbon mineralization approaches, such as:

• Open-system approaches: Ocean alkalinity enhancement or enhanced rock weathering are open-system approaches for which it is more challenging to measure and monitor carbon removal. To strengthen measurement, reporting and verification standards and protocols, a small but well-targeted amount of funding can develop long-term sites that improve the foundational scientific research base needed to better understand open-system interactions. These would include environmental impacts, measuring carbon mineralization on crop fields and in the ocean and safely applying mineralization approaches. 

Regulating the safe handling of hazardous material: The treatment, use and storage of feedstock material containing heavy metals commonly present within alkaline mine tailings and industrial waste must be well regulated. Although there are no current regulations specific to enhanced rock weathering or ocean alkalinity enhancement, these types of approaches could to some extent be accommodated under existing waste management, air and water pollution regulations.

It is crucial to ensure that such materials do not cause harm to those handling them or the communities and ecosystems in which a mineralization project is sited. Inhaling dust from certain alkaline feedstocks can be a health risk to farmers spreading it over fields, which can be avoided if the material isn’t ground past a specific size. A recent proposal by the U.S. Department of Labor to amend current federal standards to ensure that workers are protected from health hazards tied to exposure of respirable silica material would be an important step in the right direction.

• Mineralization at mine and industrial waste sites: As some mine tailing sites are located close to surface water or groundwater resources, mineralization must follow robust standards to avoid contamination. Feedstocks can in some cases be treated on-site to mitigate toxic properties. These treatments, however, require further research and testing and should be accompanied by rigorous guidelines to prevent geochemical contamination or negative health impacts. Appropriate regulation can help establish a safe research space to explore the potential of mine tailings for carbon removal and help drive innovation on how to handle them safely and efficiently.
• Mineralization in agricultural fields: Spreading ground or pulverized alkaline feedstock over agricultural fields may provide co-benefits like improving crop yields, but some types of feedstocks also contain heavy metals, which must be managed to avoid resulting in hazardous concentrations in the soil. Conservation or environmental regulation and standards must be developed or amended to include alkaline material for use in croplands. These could be informed by voluntary-market examples to help prevent these impacts. An enhanced rock weathering methodology, for example, requires all feedstocks to be analyzed for contaminants prior to and after deployment, establishing limits on ‘acceptable’ levels of contaminants based on local or national regulations.

Community engagement: Carbon mineralization projects, just like all carbon removal or industrial projects, are likely to impact the communities within which they are deployed. Once mineralization approaches receive increased policy support, and are included in more government programs, mineralization projects could be included under the Justice40 Initiative, which seeks to distribute 40% of benefits of federal investments to disadvantaged communities (such as communities that are overburdened by pollution). This would be one step to ensure that local communities in which carbon mineralization projects are hosted directly benefit from these developments.

A suite of different policies will be needed to ensure different types of mineralization can scale up and that this scale-up happens responsibly.

What Comes Next?

A diverse and robust portfolio of carbon dioxide removal solutions will require additional policies that support development and deployment to unlock their potential. The Department of Energy has made its commitment clear through the Carbon Negative Shot initiative, which aims to reach $100/tCO2 removal across carbon removal approaches that can reach large-scale, and recent announcements of upcoming funding specifically focused on mineralization. These are important steps in the right direction, but more funding and attention is needed to support research, development, demonstration, and deployment, and to ensure that it is all done responsibly.