CHAPTER 3

Carbon Dioxide–Removal Evaluation

The previous chapter covered the (1) technological and (2) nature-based CDR pathways that exist today and described the standards used to evaluate the quality of those CDR pathways. Although some airport-specific considerations were spotlighted in Chapter 2, Chapter 3 builds on this information and provides further understanding of how to evaluate the opportunities and constraints of CDR strategies within the specific context of airports.

3.1 Evaluation Process

The previous chapter provides the context of CDR pathways that exist today. Many of the pathways discussed in Chapter 2 are rapidly evolving with technology and research, continuing to assist in the evaluation and improvement of these pathways. It is important for airports to have a process to evaluate CDR so this guide can continue to be used when TRLs are further along, new pathways are developed, efficiency improves, and cost comes down. Figure 21 (repeated from this report’s summary section) shows a high-level roadmap for evaluating and implementing CDR pathways for an airport.

Understanding the CDR pathways and barriers is step one, to be completed in conjunction with using the technical tool. This will help an airport focus on CDR pathways localized for them and understand the critical barriers. Next, the communication toolkit can be used to help educate and align partners to create buy-in for a CDR project. The third step is evaluating the design and cost specifics of the various CDR technologies, implementing, and verifying. Then, the fourth step focuses on monitoring and continued verification of the pathways to ensure continued removal over time.

3.2 Barriers to Implementation at Airports

Considering the critical barriers to implementation must be a part of the initial evaluation of viable CDR pathways. Following is a list of potential barriers and airport-specific requirements to implementing CDR. Each barrier description includes insights into critical criteria to review and the regulations associated with implementing a CDR project on-site. Chapter 6 focuses on funding and financing strategies, but as a potential barrier to implementation, considerations are also discussed. An additional barrier to examine is that small airports may have more land but fewer resources than their larger counterparts and vice versa. Chapter 4, the case studies portion of this report, is intended to provide insights into the current CDR landscape for airports.

Key barriers to consider include the following:

• Grant assurances
• Fair market value

• Operating expenses
• Revenue diversion
• Lease length
• Airport layout plan (ALP)
• Environmental review
• Airspace review
• Wildlife considerations

3.3 Regulatory Coordination and Context

3.3.1 Grant Assurances

Public-use airports operate under specific requirements that are tied to receiving federal funding from FAA-administered airport financial assistance programs like the Airport Improvement Program. These requirements are called grant assurances. There are 39 grant assurances, covering a range of topics from procurement of services to the fees charged for use of an airport. There can be serious consequences if an airport fails to comply with these grant assurances, including the loss of funding for a project and the loss of eligibility to attain future grants. ACRP Web-Only Document 44: Understanding FAA Grant Assurance Obligations: Volume 1: Guidebook provides a summary of all the grant assurances, organized by subject, under which airports operate (Molar et al. 2018).

General subjects of grant assurances include the following:

• Airport access
• Leasing and user relations

• Finance and revenue
• Operation and safety
• Ownership and control
• Federal aircraft and facilities
• General federal requirements

Grant assurances are important within the context of CDR, because any CDR technique applied by an airport must still meet the requirements of the FAA. Many grant assurances also have requirements that must be applied to third parties.

Following is a list of several grant assurances that could potentially affect a CDR strategy employed by an airport, followed by detailed descriptions of some airport-specific constraints as they relate to the interplay of grant assurances and the rapidly developing field of carbon removal. It is important that these issues are considered as airport planners evaluate CDR at their airports.

• Grant Assurance 20 (Hazard Removal and Mitigation): Requires airports to make their best efforts to prevent the development of objects or buildings, or both, that may obstruct the airspace.
• Grant Assurance 21 (Compatible Land Use): Requires airports to ensure to the best of their ability that land close by must adhere to airport standards and will not interrupt normal airport operations.
• Grant Assurance 22 (Economic Nondiscrimination): Requires that the airport be available as an airport for public use on reasonable terms and without unjust discrimination to all types and classes of aeronautical activities, including commercial aeronautical activities offering services to the public at the airport.
• Grant Assurance 24 (Self-Sustainability): Requires that an airport must charge fair market value to nonaeronautical users but may charge less than fair market value to aeronautical users.
• Grant Assurance 25 (Airport Revenues): Requires that fair market value lease revenue will be paid on an annual basis and that revenue be dedicated to the airport fund and used for aviation purposes. Any nonaeronautical use would need to determine fair market value for any parcels that would be leased for nonaeronautical use, such as CDR.
• Grant Assurance 29 (Airport Layout Plan): Requires the sponsor to maintain an up-to-date ALP reflecting planned or constructed projects. Sponsors will need to initiate FAA review and obtain approval of CDR facilities and uses proposed on the airport. Having a project on an ALP would also trigger the National Environmental Policy Act (NEPA) environmental documentation review prior to construction unless it was determined to be exempted under Section 163. Section 163 allows the FAA to determine whether an airport’s actions are under FAA jurisdiction, or if outside aeronautical use could be exempted from NEPA requirements. However, special purposes, such as the Clean Water Act, may still apply to an action, even if NEPA is not required.
• Grant Assurance 31 (Disposal of Land): Requires a land release from aeronautical use to a long-term nonaeronautical use. Since a land release may be needed to apply a CDR technique, the airport sponsor may need to go through the land-release process.

3.4 Fair Market Value

Grant Assurance 24 relates to self-sustainability, when an airport must charge fair market value to nonaeronautical users but may charge less than fair market value to aeronautical users. A sponsor must set fees for nonaeronautical use based on fair market value, which can be determined by a cost-recovery model or based on fair market value supported by an appraisal. This has a few implications for CDR.

The FAA defines aeronautical use as “any activity which involves, makes possible or is required for the operation of aircraft, or which contributes to or is required for the safety of such operations” (1999). CDR is not a traditional aeronautical use, and as a nonaeronautical use it would be subject to paying fair market value for any land, as dictated by an appraisal.

The FAA has developed a list of exceptions for a few categories of nonaeronautical uses of airport property for which a sponsor may charge less than fair market value:

Under the Final Policy, the lease of airport property to a unit of the sponsoring government for nonaeronautical use at less than fair market value is considered a prohibited revenue diversion unless one of the specific exceptions permitting below market rental rates applies. If a sponsor’s use of airport property qualifies as community use, and the other requirements for community-use leases are satisfied, the FAA would not object to a lease at less than fair market value. Qualified uses could include park or recreational uses or other public service functions. However, such use would be subject to special scrutiny to ensure that the requirements for below FMV community use is satisfied. The community use provision of the Final Policy does not apply to airport property used by a department or subsidiary agency of the sponsoring government seeking an alternative site for the sponsor’s general governmental purposes at less-than-commercial value. For example, a city cannot claim the community use exception for a nominal value lease of airport property for a municipal vehicle maintenance garage. Such usage, while beneficial to the taxpaying citizens of the sponsoring government, would be difficult to justify as benefiting the airport by improving the airport’s acceptance in the community.

(FAA 1999)

While CDR is not clearly within these exceptions, there could be an argument for stating that CDR provides a public-service function, thereby benefiting the community. In cases where a third-party developer would develop land for CDR purposes in exchange for the carbon-removal benefits being given to the airport, the ability to lease the land to a developer at less than fair market value could make the economics of some of the CDR pathways more feasible. There is precedence for solar projects at airports receiving less than fair market value. Additionally, more research into the fair market value for pore space (allowing developers to lease the geologic pore space at an airport for sequestration purposes) is needed. To date, the FAA has given guidance to use the FAA Advisory Circular 150/5100-20, Guidance on the Extraction of Oil and Gas on Federally Obligated Airports (2016), relative to oil and gas leases to guide lease requirements for pore space.

3.4.1 Operating Expenses

To date, the FAA’s guidance on the purchase of offsets consists solely of the offsets being listed as a potential method to address GHGs for airports (see more discussion under the Revenue Diversion section). An additional element to consider is whether airports can now, or in the future, exact fees related to the social cost of carbon.

Under Grant Assurance 24, for aeronautical uses other than the airfield, the sponsor can charge up to fair market value, as long as the charges (a) do not unjustly discriminate and (b) recover the users’ fair share of the costs of the airport facilities. This means that, in general, the costs of the airport operation can be passed along to its aeronautical users (airlines, general aviation users, etc.).

Current operation and maintenance expenses are included in the fair share of costs relayed to users and are based on the FAA Policy and Procedures Concerning the Use of Airport Revenue; these costs can include environmental mitigation for projects. In the past, environmental mitigation has included impacts such as wetland mitigation that are required under federal law.

Historically, emissions-related fees have been treated more akin to noise-related landing fees than wetland mitigation, meaning that the cost of emissions has not been relayed to the user.

3.4.5 Environmental Review

Federal actions that trigger the need for an environmental review under the NEPA include the FAA’s conditional, unconditional, or mixed approval of the following:

• Federal funding for airport planning and development projects, including separate funding plans and specifications for those projects (i.e., federal funding for a solar project);
• New or changed ALP (i.e., DAC or other units that need to be listed on an ALP); and
• An airport sponsor’s request to release airport land from a federally obligated, public-use airport when the land would be used for nonaeronautical purposes, including entering into long-term leases (i.e., a public–private partnership may require a land release).

As with any airport project, it is important that the airport sponsor coordinate early with the FAA Regional Airports Division and District Offices (ADOs) and seek guidance on required environmental and agency coordination, as well as potential federal funding opportunities. As part of the planning process for CDR projects, it would be beneficial to inventory and document potential site impacts related to wetland, cultural resources, threatened/endangered species, hazardous materials, and water quality degradation from erosion and sedimentation. After consulting with the region or ADO about the project and environmental issues, the sponsor will provide the FAA with environmental information to support NEPA analysis (i.e., a categorical exclusion or an environmental assessment).

3.4.6 Airspace Review

In September 2022, the FAA issued Advisory Circular 150/5190-4B, Airport Land Use Compatibility Planning, which replaced the FAA 2010 guidance, “Interim Guidance on Land Uses in the Runway Protection Zone [RPZ].” In this advisory circular, the FAA identifies where infrastructure is considered compatible relative to CFR Part 77 imaginary surfaces (see Figure 22). It states that certain types of infrastructure, for example, are not considered a compatible land use within an RPZ, approach zone, or transitional surface (7:1). With additional review by the FAA, types of infrastructure may be permitted within the horizontal surface and conical surface. This may be also the case with a CDR installation.

Part 77 surfaces are three-dimensional airspace areas that surround a runway and are used by the FAA through 14 CFR Part 77 to evaluate whether a structure or vegetation could present obstructions or could be considered a hazard to air navigation. A DAC or other CDR installation that has vertical considerations on airport property could potentially be considered an obstruction if located within a Part 77 surface or RPZ. Any CDR installation on airport property that falls within an approach surface or RPZ and that has vertical properties would require early discussion with the FAA to determine feasibility. An imaginary surface analysis may need to be performed to determine feasibility.

FAA Advisory Circular 150/5190-4B does not specifically prohibit CDR land uses within a RPZ, but this should be discussed with the FAA early in the process if a sponsor is considering a CDR project within a RPZ. The sponsor may need to submit a range of alternatives to the FAA if the FAA were to approve of a CDR project. Currently, compatible land uses within an RPZ that could be similar to a CDR project include the following: farming (in the absence of wildlife concerns); airport service roads (if needed to access/maintain the CDR installation); and underground facilities. The most common airspace issues with a potential CDR project located within a RPZ would likely be related to height issues and visual obstructions.

Regardless of height, all projects at airports require submittal of a Notice of Proposed Construction or Alteration Form 7460 under Part 77 to ensure the project does not penetrate the imaginary surfaces (14 CFR Part 77) around the airport or cause radar interference. The FAA will conduct an aeronautical study of the project and will issue a determination of hazard or no hazard.

3.4.7 Wildlife Considerations

It is critical to account for potential wildlife hazards because of CDR project development on airport property. Wildlife concerns will likely be most relevant with nature-based CDR pathways. FAA Advisory Circular 150/5200-33C, Hazardous Wildlife Attractants on or near Airports, recommends a 5,000- to 10,000-foot separation (depending on whether an airport serves piston-powered aircraft or turbine-powered aircraft) between wildlife attractants and aircraft operations. For the protection of approach, departure, and circling airspace, the FAA recommends a 5-mile distance between the wildlife attractants listed above and the nearest aircraft operations area. Case studies on the topic indicated that the USDA has concerns with wildlife because of increasing plantings near airports. Despite minimal research at this time, it is anticipated that nature-based CDR pathways will likely attract wildlife. In general, wildlife is attracted to areas that mimic their natural habitat and provide access to key resources. The nature-based CDR pathways that are most likely wildlife attractants include afforestation/reforestation, soil-based, and wetland restoration. Some technological pathways, such as DACS, could provide nesting habitats or hazardous conditions for wildlife. Conducting a wildlife review on select pathways with a USDA or wildlife officer would help with understanding and addressing these concerns.