Building Direct Air Capture Responsibly from the Ground Up

The science is clearer than ever that to prevent the most dangerous impacts of climate change, we not only have to reduce emissions, but also pull CO₂ directly out of the air with carbon removal. The U.S. Long-Term Strategy indicates that in addition to reducing emissions by at least 85% around half a billion tons of technological carbon removal will likely be needed by mid-century to meet our net-zero climate goal.

One technology used for carbon removal, direct air capture (DAC), has seen growing private investment, public research funding and most recently $3.5 billion under the United States’ Bipartisan Infrastructure Law to build four large-scale DAC projects.

With all of this interest and investment, the coming years will more than likely see an increasing number of DAC plants constructed across the country. But what impacts will these projects have on nearby communities? As DAC is scaled to provide necessary carbon removal, how can we avoid historical and present practices in infrastructure siting that burden communities of color and fail to bring benefits to communities that need them most?

Because DAC is only operational on a small scale today, it can be difficult to assess the future impacts of expanding DAC capacity and their supporting infrastructure in the U.S. Doing so, however, is critical to scaling DAC in an equitable and environmentally friendly way.

To begin to answer some of these critical questions, a new WRI working paper synthesizes the best available data on the impacts of various DAC systems, and offers preliminary recommendations for community engagement and policy guardrails that will help ensure DAC is scaled up responsibly.

What does it mean to scale Direct Air Capture responsibly?

Responsibly scaling DAC requires the thorough assessment of the economic, environmental and social impacts of siting and operating plants, paired with effective action to reduce potentially detrimental impacts and equitably provide benefits. We break down the components of a responsible scale-up and lay out what we know about potential impacts of building DAC plants.

Assessing environmental impacts of Direct Air Capture

To understand the environmental impacts of DAC plants, it’s first helpful to conceptualize a DAC plant. DAC plants are machines that push air over certain types of chemicals, which selectively react with CO₂ in the air. Once captured, heat is typically applied to release the CO_2, which is then compressed and sequestered underground or sold for use in certain products, such as concrete building materials.

DAC plants today vary in scale from capturing 1 metric ton (tonne) of CO₂ per year up to 1 million tonnes (Mt) per year — the largest plant in operation today captures 4,000 tCO₂/yr with one MtCO₂/yr scale plant in development; for comparison, a typical passenger vehicle in the U.S. emits 4.6 tonnes of CO₂ per year. The different sizes and possible configurations of DAC plants mean that DAC plants can be sited in a variety of locations and can be tailored to local needs. It also means that the impact of DAC will differ from plant to plant.

Today, there are two leading DAC system types that use different chemicals — liquid solvent or solid sorbent, which both require energy input of around 80% heat and 20% electricity. Solvent plants require higher temperatures, so are powered by natural gas with carbon capture today, while sorbent plants can be powered by renewable sources or waste heat.

WRI research finds that overall, DAC plants are expected to produce zero or almost zero onsite emissions that could negatively impact human health or the environment.

Solvent plants produce minimal, but non-zero, amounts of “drift losses” — aerosolized solvent droplets that can enter the atmosphere. Technologies called demisters can, however, remove liquid droplets, significantly reducing the amount of drift loss. Chemicals used in sorbent plants would degrade over time as heat is applied to release captured CO₂, but those degradation products (e.g., ammonia) are expected to be contained within the DAC plant and not released into the environment. To help reduce uncertainty and public concern, information on these kinds of impacts for existing and planned plants should be easily accessible.

Designing and siting DAC systems to minimize impact

A major determinant of a DAC plant’s impact will be the energy source powering it. Renewables produce no onsite emissions, however they often require extensive land area. New DAC plants could connect to the grid for power, but to avoid competition for renewables with other sectors, scaling DAC will require building significant new renewable capacity.

For a million-tonne-per-year DAC plant powered entirely by solar PV, around 34 km² of land would be needed to produce the 270-280 MW of power required (other renewables like geothermal take up less space). In contrast, natural gas with carbon capture and sequestration is currently used to provide high temperature heat for solvent DAC systems, and takes up much less space — 0.4 km² total with the DAC plant. Today’s leading solvent DAC system uses natural gas fired in a high-oxygen environment, which makes carbon capture easier, but produces minimal onsite emissions: for every tonne of CO₂ captured from the air, around 0.012 tCO₂ is emitted. Nitrogen oxide emissions are also significantly reduced — 70-90% lower than conventional natural gas firing. Extracting and transporting natural gas also causes negative upstream environmental and social impacts, and economy-wide decarbonization requires decreased reliance on natural gas over time.

Then there’s the issue of water. DAC plants, and particularly solvent plants, require water to operate, which may pose challenges if DAC plants are sited in water-scarce environments. To address this, DAC could be sited in cooler and wetter climates. New sorbent technologies are also in development that use less water overall and can even produce water.

DAC land use, water, and energy needs show how important it is to carefully assess the location of DAC plants, to minimize community and environmental impacts and select systems that best suit local resource availability.

The environmental impacts of DAC don’t just occur onsite; impacts are also distributed throughout the supply chain. Building DAC plants would require a moderate and incremental scale up of annual cement and steel production (~1-3% increase in U.S. production), while production of chemicals used for the solvent and sorbent would need to scale up more significantly. Producing more of these materials to meet DAC demand will increase emissions and other impacts associated with production.

As the exact impacts of a DAC plant will vary from project to project, depending on plant configuration and project location, environmental assessments should be conducted for each proposed project to identify potential negative impacts. Additionally, project design and plant location should be tailored to reduce community and environmental impact.

What does responsibly scaling Direct Air Capture look like?

First, regulations should ensure DAC is developed safely and equitably. While the regulation of U.S. infrastructure and industry is designed to prevent harmful impacts and the release of dangerous substances, environmental regulations have historically not been effective in preventing disproportionate environmental burdens from falling on low-income communities and communities of color. Regulations also have not always been enforced sufficiently, allowing for the ongoing release of pollutants that have harmed these and other communities. Because of this, the policies and regulations that will govern DAC must be critically examined to ensure that DAC is developed safely, and that the burdens and benefits of DAC infrastructure are equitably distributed.

Second, DAC offers an opportunity for more inclusive and equitable decision-making processes that will guide its scale-up, particularly as it is a relatively new industry. These processes should prioritize community input — including community opposition to a project — and minimize negative local impacts to the extent possible. There should also be opportunities available for communities to determine siting suitability and negotiate robust benefits. Potential benefits will vary by community but could include things like providing a certain number of jobs to community members, funding job training or apprenticeship opportunities, providing financial compensation, or investing in other aspects of the community as desired.

A key step in this process will be more research to clarify local environmental and social impacts of building and operating DAC plants with different configurations and in different locations. Information can then be transparently communicated, especially to communities that may host projects.  

Third, the process to decide the location for a new DAC facility: As a major impact of DAC will be the land use footprint for the plant and the energy source (whether the energy source is onsite or elsewhere), the process for deciding DAC plant location will be a key to determining who is impacted. Even though DAC plants will not be emitting hazardous pollutants like chemical plants or other industrial facilities, they will cause other impacts like noise, facilities visible from homes or businesses, and new roads and increased traffic could increase noise and pollution. While CO₂ transport and sequestration infrastructure, necessary to permanently remove the CO₂ from the atmosphere, is outside of the scope of WRI’s paper, infrastructure like CO₂ pipelines or CO₂ injection sites may have impacts that are of concern to communities. These concerns will need to be carefully assessed and negative impacts will need to be mitigated. 

Fourth, a key benefit of DAC plants is expected to be job creation, both onsite to operate the plant and in planning, construction engineering and other functions in the supply chain. Recent analysis finds that each million-tonne DAC plant could provide more than 3,000 jobs, with around 270 jobs at the plant itself. For local workers to benefit from job creation, however, job training and apprenticeship programs will be needed to make sure that workers have necessary skills.

However, the benefits that DAC plants could offer are only theoretical until they are negotiated and received. Use of legally binding mechanisms can help ensure that communities have the opportunity to benefit from available jobs and provide a mechanism to negotiate for other types of benefits beyond jobs.

These agreements could take the form of a Community Benefit Agreement, a negotiated legal agreement between community groups and project developers that guarantees community benefits in exchange for a community’s agreement to accept the project, or a Project Labor Agreement, which is an agreement between contractors and unions, laying out the terms for a project. Project Labor Agreements can include Community Workforce Agreements, which require that the contractor hire a negotiated percentage of local, low-income or other marginalized workers, or that they collaborate with local organizations to provide job training programs and provide job quality specifications.

What kind of policy can support responsible scaling?

Policy guardrails at the federal and subnational levels, as well as private sector action will be key to ensuring responsible DAC development. Here are three policy and procedural recommendations that can help guide responsible scale-up:

1. Federal Action

President Biden’s Council on Environmental Quality has shown a commitment to just deployment of carbon removal and carbon capture, utilization and sequestration. These commitments should be further codified into law and normalized as standard practice. The historic investments that the federal government is making in carbon removal can be used to provide guardrails and incentives to ensure that DAC is scaled responsibly and with environmental justice as a key concern. This could mean that every DAC project that receives federal funding:

• Is required to complete social and environmental impact assessments to identify sites that are acceptable
• Conducts meaningful community engagement using skilled facilitators to ensure that all stakeholders, including marginalized community members, can provide input on project development
• Is powered by low-or zero-carbon energy sources with rigorous criteria to reduce environmental impacts
• Establishes job training programs in communities adjacent to DAC plants and standards for high-quality employment

The federal government can also invest in research, development and demonstration to improve efficiency and reduce environmental impact of DAC technologies as well as for improving monitoring, reporting and verification capacity.

2. Local Action

Local policy, such as equity-informed zoning and planning, can help to counteract historical patterns of land use that concentrate locally unwanted land uses in low-income communities and communities of color. Local environmental justice initiatives can assemble advisory panels to provide input on zoning and planning to ensure that infrastructure such as DAC is distributed equitably.

3. Private Sector Action

Private companies are increasingly investing in carbon removal, and specifically in DAC, because of the opportunity it provides for permanent carbon removal and sequestration on a large scale. While federal oversight is critical to ensuring responsible DAC scale-up, companies can also help to hold DAC projects to a high standard. Companies can ensure that when they purchase carbon credits from DAC projects, the projects have undergone review to verify that they have conducted adequate environmental and social impact assessments, meaningfully engaged community members to address concerns and ensured that benefits accrue to host communities.

As a relatively new industry, DAC  presents the opportunity to scale responsibly, and every sector of society will need to be engaged to ensure that this occurs. The first step in that process, and in any individual DAC project, is to better understand how these facilities will impact communities and to ensure that DAC facilities bring real benefits in addition to needed carbon removal.