Airport Renewable Energy Projects Inventory and Case Examples (2020)

Below is the uncorrected machine-read text of this chapter, intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text of each book. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

50 The research included in this synthesis is the basis for a summary of airport renewable energy projects. It also sheds light on the overall state of renewable energy generation at U.S. airports. Further, the research includes an overview of practical information intended to be useful to other airports when considering technologies; siting issues; ownership and financing; and plan- ning, permitting, and implementation for renewable energy projects. It also provides context for the drivers behind such airport projects. The issues addressed in the previous sections can be effectively considered in the presenta- tion of the following case examples, which discuss how individual airports have planned and implemented renewable energy projects. Each example addresses the relative ease or challenge of renewable energy implementation. When possible, case examples also illustrate how decision- making tools, funding mechanisms, outside stakeholders, regulations, and other incentives or disincentives impacted the initiative’s overall implementation. The list of potential case examples was proposed and reviewed by the synthesis expert panel, with the objective of evaluating a variety of technologies and designs at airports of different sizes and in different geographic areas. The author contacted these and additional airports on the basis of known or subsequently learned information on different types of renewable energy technologies implemented by airports. Telephone interviews were conducted, with questions sent in advance and used to guide the development of each case example (see Appendix D). The variety of final case examples presented below is intended to maximize their applicability to the widest audience. The list of case examples is provided in Table 1. The table includes the airport name, its FAA identification code, state, NPIAS hub classification, type of renewable energy technology pro- filed, date commissioned, project ownership structure, and a description of the project. The locations and types of the airports profiled in the case examples are shown in Figure 41. The final list includes 10 airports (three large, two medium, one small, three nonhub, and one general aviation) within seven FAA regions. The case examples include four renewable energy technologies plus battery storage. The case examples are presented in the following pages. They are presented in alphabetical order by airport name. C H A P T E R 4 Case Examples

Case Examples 51 Airport Code Hub Class Technology Date Project Ownership Description Appleton International Airport, WI ATW N Geothermal, solar PV, and solar thermal 2010– present Airport Solar hot water panels on roof of airport’s general aviation terminal generate thermal heat Brunswick Executive Airport, ME BXM GA Anaerobic digester 2016 Private third party 1-MW anaerobic digester generates electricity from organic matter including wastewater treatment plant sludge and septic waste Charleston Yeager Airport, WV CRW N Canopy- mounted solar 2019 Airport FAA funding for airport solar project on top deck of parking garage Denver International Airport, CO DEN L Multiphase solar program 2008– present Private third party and airport Four solar PV arrays have been installed on airport property with a combined capacity of 10 MW DC Dallas/Fort Worth International Airport, TX DFW L Renewable electricity purchasing 2006– 2019 Airport Purchase of 176,000,000 kW- h/year from renewable and competitive energy supply sources including landfill gas, facilitating ACA Level 3+ carbon neutral accreditation Eastern Iowa Airport, IA CID S Geothermal heating and cooling 2018 Airport Heating and cooling for 54,000-sf expansion of airport terminal Ketchikan International Airport, AK KTN N Biomass 2016 Airport 500-MBH biomass boiler to heat airport terminal Nashville International Airport, TN BNA M Lake plate geothermal cooling 2016 Airport Geothermal lake plate system to use cooling capacity of abandoned quarry on airport property, funded with AIP 512 grant San Diego International Airport, CA SAN L Solar PV paired with battery storage 2016– present Airport and private third party 5.5 MW of solar PV and 2 MW/4 MW-h lithium-ion battery storage St. Louis- Lambert International Airport, MO STL M Ground- mounted community solar 2019 Third- party utility Lease of land to utility for 1-MW ground- mounted solar project Note: Hub classifications from the NPIAS: L = large; M = medium; S = small; N = nonhub; GA = general aviation. MBH = one thousand British thermal units per hour. Table 1. Case examples of airport renewable energy projects.

52 Airport Renewable Energy Projects Inventory and Case Examples 4.1 Renewable Energy Program at Appleton International Airport (ATW), WI Figure 41. Case example airports. Airport Code: ATW Technology: • Solar PV (roof-mounted and canopy-mounted) • Solar thermal • Geothermal heat pump system Hub Classification: Nonhub Project Owner: Airport FAA Region: Great Lakes Operations Date: 2010 to the present 4.1.1 Introduction Renewable energy can be integrated into an airport to support a variety of long-term initiatives. Because renewable energy technologies do not require the delivery of fossil fuels, but instead use on-site resources that are naturally replenished, they provide benefits that cannot be achieved by other power options: namely, zero emissions and uninterrupted power supply. Increasing renewable energy consumption (from either on-site generation or off-site purchasing) can help the airport strive toward a net zero or carbon neutral goal. Building the renewable facilities on site and coupling them with energy storage, such as lithium-ion battery technology, can

Case Examples 53 move the airport toward implementation of a microgrid, whereby the airport can continue to be powered even in the event of a regional disruption of the power supply. Appleton Inter- national Airport (ATW) has been incorporating renewable energy on site as part of its long-term sustainability master plan in an effort to realize its near-term future as a net zero facility and self-sustaining microgrid. 4.1.2 Project Details In 2010, ATW installed as technology demonstration projects both a 50-kW solar PV facility on the roof of the main terminal concourse and a 12-panel solar thermal facility on the terminal roof. In 2013, ATW constructed a LEED-Platinum general aviation terminal building, which included a 25-kW rooftop solar PV facility and a geothermal heat pump system. In 2017, ATW constructed a 230-kW solar canopy project over surface parking adjacent to the main airport terminal building. In 2019, the airport constructed a second 230-kW solar canopy project next to the previous one. 4.1.3 Implementation Discussions about the airport’s sustainability issues first turned into action in 2006, with a public display in the airport terminal. Seeking to understand how the airport could increase energy efficiency to achieve both economic and environmental objectives, ATW completed a facilities assessment of its terminal and maintenance buildings in 2008. Then, following the economic downturn, ATW applied to ARRA’s Energy Efficiency and Conservation Block Grant Program, through which it received funding to deploy solar PV and solar thermal demonstration projects at the airport. In 2011, ATW was selected by FAA as one of 10 airports to receive grant funding for the develop- ment of an airport sustainability master plan. The completed plan included the airport’s goals of achieving net zero energy for the main terminal by 2030 and developing a net zero energy general aviation terminal as a demonstration project in the near term. In the plan, the airport showed how it could achieve these goals through (1) a 70% reduction in energy use from its 2010 baseline and (2) development of renewable energy projects to meet half of the remaining demand. The plan also included a list of the energy efficiency and renewable energy projects necessary to achieve the airport’s goals. ATW tracks its energy use, changes associated with energy efficiency, and renewable energy, and the airport’s projections for achieving its long-term objectives are shown in Figure 42. It uses energy use intensity, which is a measure of a building’s energy use as a function of its size, according to the EPA Energy Star program. A significant opportunity will present itself through the expansion of the main terminal; this project, which is expected in 2021, which will feature energy efficiency and renewable energy components—including a geothermal heating and cooling system—that will drive down energy use to about 61% of the airport’s 2010 baseline. ATW is also considering how it can include energy infrastructure improvements that support a potential airport microgrid. The recently constructed solar canopy projects illustrate how the airport is implementing renewable energy consistent with its sustainability master plan. Each project consisted of two canopies. The first canopy was funded with AIP discretionary funding, which for ATW meant 95% FAA funds and 5% local matched funds. The second canopy was funded by supple- mental funds at the end of the fiscal year, with a 50% federal grant and 50% state match. FAA financially supported ATW’s sustainability planning and then provided funding for project implementation.

54 Airport Renewable Energy Projects Inventory and Case Examples 4.1.4 Project Benefits • Solar canopies provide the added benefit of covered parking, which increases customer satisfaction. 4.1.5 Lessons Learned • Projects are part of an integrated strategy approved by the airport executive team, which supports project implementation. • It is beneficial for the airport to regularly report on sustainability and renewable energy benefits to FAA and other regulatory authorities. 4.2 Anaerobic Digester at Brunswick Executive Airport (BXM), ME Figure 42. ATW’s path toward net zero energy (EUI = energy use intensity). Airport Code: BXM Technology: Anaerobic digester Hub Classification: General Aviation Project Owner: Private third party FAA Region: Eastern Operations Date: April 2016 4.2.1 Introduction Energy that is produced by organic matter is generally referred to as bioenergy. Bioenergy is used as a fuel in electric power plants and in building furnaces and boilers; in addition, when distilled to liquid form, bioenergy can be used as biodiesel for cars and as bio–jet fuel for aircraft. The source

Case Examples 55 of organic matter for fuel can be crops grown as feedstock or waste organics left over from other uses. An anaerobic digester is a vessel that captures biogas from naturally degrading organic matter, which can then be combusted to generate electricity. The Brunswick Executive Airport (BXM) is home to an anaerobic digester that generates 1 MW of electricity and transmits the power into the local electric grid, which is owned by the Midcoast Regional Redevelopment Authority (MRRA). 4.2.2 Project Details The project is a 1-MW anaerobic digester located on airport property at the southern edge of the airport apron. MRRA, which owns and operates the airport, leases about 4.25 acres of land to Village Green Ventures (VGV), the facility owner and operator. MRRA purchases electricity generated by the plant through a PPA. The purchase price (11.5 cents per kW-h) is lower than the combined rate available from outside generation and distribution. The digester is fueled by a variety of municipal and commercial organic waste sources in the region, including wastewater treatment sludge. When the digester is operating at full capacity, the electricity generated pro- vides approximately 20% of the electricity needs of the Brunswick Landing campus where the airport is located. Planned expansion in 2020 will increase the generation to 2 MW. 4.2.3 Implementation BXM is located at the former Naval Air Station Brunswick (NASB) which was closed as part of the Base Realignment and Closure (BRAC) process in 2005. As part of BRAC, the Brunswick Local Redevelopment Authority, the Town of Brunswick, the U.S. Department of Defense, and local stakeholders published the Reuse Master Plan to redevelop the former base, now called Brunswick Landing, Maine’s Center for Innovation. MRRA was established in 2007 to imple- ment the plan. MRRA is the largest property owner at Brunswick Landing. It manages and owns significant assets of the former NASB, including 1,424 acres, the airport, utilities (power and water), and transportation infrastructure. The NASB Reuse Master Plan included as a central tenet the establishment of a renewable energy center of excellence to attract renewable energy companies and innovation to the region. The plan also set a goal of generating and using 100% of the power at the former base, now called Brunswick Landing, in the form of renewable energy. Consistent with these objectives, MRRA was contacted in 2012 by VGV about the opportunity to develop an anaerobic digester to capture and burn methane and generate renewable electricity. After receiving a commitment that MRRA would purchase the electricity produced by the digester, VGV moved forward with the permit- ting and financing for the facility, a process that involved working with FAA to amend the ALP, reviewing the potential for airspace hazards, approving the lease language, and completing an EA. The anaerobic digester, shown in Figure 43, has been operating since 2016. It receives feed- stock supply from off-site providers, including sludge from regional wastewater treatment plants, as fuel. The digester is one of the largest such facilities in Maine. Because the airport and the larger Brunswick Landing campus are connected to the regional electric grid, they use the full amount of power from the digester when it is operational—reducing the amount of power required from the electric grid—and increase grid power purchasing when the digester is not operational. Brunswick Landing is also host to a 1.5-MW DC solar photovoltaic facility that similarly reduces the amount of power required from the regional electric grid. 4.2.4 Project Benefits • The project helps MRRA achieve its renewable energy goals and provides 100% green power to its Brunswick Landing customers.

56 Airport Renewable Energy Projects Inventory and Case Examples • The digester generates power on site, thereby decreasing reliability on local energy and supporting a longer-term concept of a microgrid. • The project supports the overall Brunswick Landing economic development goals of attracting renewable energy and technology businesses. 4.2.5 Lessons Learned • The project is a great opportunity for reuse of former military property. • The electricity output of the anaerobic digester has varied as the facility has adapted to changing feedstocks. As a result, it has not produced a steady or reliable amount of electricity. • The digester facility has proved to be compatible with airport operations. 4.3 Airport-Owned Solar PV Project at Charleston Yeager Airport (CRW), WV Figure 43. Anaerobic digester at Brunswick Executive Airport, ME. Airport Code: CRW Technology: Solar PV Hub Classification: Nonhub Project Owner: Airport FAA Region: Eastern Operations Date: September 2019 4.3.1 Introduction Airports have been pursuing the development of solar PV projects in a variety of ways. Some projects are financed and developed by private partners while others are owned and operated by the airport. Some projects are located on underused airport land, and others are integrated into the airport’s built environment. The Central West Virginia Airport Authority (CWVAA) recently completed a project at the Yeager Airport in Charleston that was funded primarily by an FAA grant. The project demonstrates the option of developing an airport-owned project and providing power directly to airport facilities.

Case Examples 57 4.3.2 Project Details The Yeager Airport solar project comprises 1,701 solar PV panels on the top deck of the airport’s long-term parking garage. It has a combined power rating of 630 kW, which is sufficient to support the energy needs of the airport’s two parking garages and equivalent to the power consumed by 70 average households. The power is consumed directly on airport property, thereby reducing the amount of power purchased from the utility at an expected annual cost savings of $50,000. 4.3.3 Implementation The CWVAA has been planning for the implementation of the solar PV project since 2014, with the goal of enhancing the sustainability objectives at Yeager Airport. In 2012 and 2013, the CWVAA prepared an energy assessment that calculated the airport’s baseline energy use and projections for future demand. As part of its sustainability efforts, the CWVAA was incorporating gate power projects with electric ground power and preconditioned air units to eliminate aircraft jet fuel emissions at the gate and to improve local air quality. These projects were expected to increase electricity demand by about 6%. The CWVAA then created the Green Energy Initiative to focus future airport development on energy efficiency and self-sufficiency. The primary components of the initiative are to (1) maximize use of nonaviation properties, (2) increase energy self-sufficiency, (3) minimize the airport’s carbon footprint, and (4) enhance economic and sustainable development. Because the airport is located in a region impacted by poor air quality, the initiative also sought to develop projects that reduce emissions. The electricity provided to customers in the region includes a baseload from coal-fired power plants, which represented approximately 97% of the region’s annual operations in 2018, and natural gas peaker plants energized during periods of high energy demand. These peaker plants operate approximately 3% of the year. The CWVAA assessed opportunities to develop clean energy on airport property to meet its long-term needs; the group also identified a strategy for developing on-site solar energy in a multiphase program to meet the airport’s baseload needs and to reduce its energy needs from coal plants. In assessing financing options for the solar projects, the CWVAA determined that a private market in West Virginia was not strong and that pursuing a grant from FAA would be the best opportunity to develop a solar energy project. The CWVAA was initially a finalist to receive an FAA grant for solar projects in 2014. However, available funding had to be diverted in March 2015 to repair a sudden collapse of land in the runway safety overrun area. The CWVAA applied again for a grant from FAA under its Section 512 energy efficiency program and was awarded $3.5 million in 2018. The grant would pay for 90% of the project costs, with the remaining 10% funded by the state. In evaluating siting options, the CWVAA assessed locations both on the ground and on top of buildings. It ultimately selected an overhead racking system over the top deck of Parking Garage A to meet its objectives. The project is shown as Figure 44. The orientation of the arrays is to the southwest at 235 degrees, the alignment of the existing parking garage, thereby enhancing the project’s stability and minimizing engineering costs. The design was evaluated for glare potential, and its orientation avoids glare impacts to comply with FAA’s solar policy and ocular hazard standard. The site also provides excellent visibility and a pleasing aesthetic to showcase the airport’s commitment to its sustainability objectives. 4.3.4 Project Benefits • The project reduces the airport’s long-term electricity costs. • It is consistent with long-term planning objectives to achieve energy independence and move toward net zero carbon. • The project location is highly visible in demonstration of the airport’s commitment to sustainability.

58 Airport Renewable Energy Projects Inventory and Case Examples 4.3.5 Lessons Learned • Airport funding needs can change quickly, but these changes should not alter the airport’s long-term planning objectives. • Project success is strongly influenced by the support of airport management and a committed champion. • The airport’s decision to pursue renewable energy can have a wide regional effect. 4.4 Comprehensive Long-Term Solar Photovoltaic Program at Denver International Airport (DEN), CO Figure 44. Solar project on top deck of parking garage at Charleston Yeager Airport, WV. Airport Code: DEN Technology: • Solar PV (ground-mounted and canopy- mounted) Hub Classification: Large Project Owner: Private third party and airport FAA Region: Northwest Mountain Operations Date: 2008 to present 4.4.1 Introduction The opportunities for integrating renewable energy are created by public programs designed to develop markets by subsidizing costs and mandating purchasing. A variety of programs have been enacted at the federal, state, and local levels, from the federal investment tax credit, which allows tax-paying entities to monetize credits and reduce the cost of project investment, to renewable portfolio standards, which require utilities to purchase a minimum percentage of the total electricity distributed to customers from a renewable source. While a variety of renewable technologies have been supported by incentives, solar PV has been the most accessible renewable energy technology for airports because of its compatibility with the airport-built environment. Since 2008, when it completed its first solar PV project, the City and County of Denver Depart- ment of Aviation has developed solar projects and procured renewable electricity for use at

Case Examples 59 Denver International Airport (DEN) through a variety of methods and initiatives by responding to opportunities that maximize economic and environmental benefits. 4.4.2 Project Details DEN has completed the following solar PV projects, listed in Table 2, in response to the associated renewable energy programs. 4.4.3 Implementation The initial four solar projects developed between 2008 and 2015 were initiated under the Solar*Rewards program offered by the utility Xcel Energy. Xcel Energy sought cost-effective locations for solar projects to be developed by private companies with the power consumed on site. Xcel would then acquire the renewable energy certificates (RECs) and have them “retired” to meet its state-mandated renewable energy obligations under Colorado’s RPS. These sites are located “behind the meter” on airport property, allowing DEN to offset its energy demand through a PPA with the developer. Though these sites were initially easy to develop and connect to DEN’s grid to serve its energy demands, the limitations of existing substations and transmission line capacity have made additional projects more costly. In 2016, DEN hosted a fifth solar project, a solar canopy facility with battery storage, as part of a transit-oriented development microgrid demonstration on airport property. This project is shown in Figure 45. The project, part of the Colorado Innovative Clean Technology demonstra- tion, was developed by Xcel Energy to evaluate new technologies and potential services. The microgrid is powered by a 1.3-MW AC solar canopy and sustained by a 1-2 MW-h lithium-ion battery storage system. The project was installed at an airport parking garage and connected to the headquarters of the Panasonic Enterprise Solutions Company across the street. Xcel owns the system and leases property from DEN, while Panasonic operates and services the system. If a disturbance is detected in the grid, the system automatically shuts down the solar and discon- nects the microgrid from the regional grid while continuing to supply power to the Panasonic building from the battery. The utility is evaluating several value propositions (power quality, arbitrage, etc.), and DEN is considering opportunities for similar applications. Description Location Ownership Type Capacity Program Lease and PPA Four projects on airport land Private Ground- mounted 10 MW Solar*Rewards Lease Airport garage Utility Canopy 1.6 MW Microgrid pilot PPA Six locations (two on airport) Private Ground- mounted 4.8 MW Community solar PPA One site off airport Private Ground- mounted 4.9 MW Renewable*Connect Integrated into new airport development Concourse expansion Airport Rooftop 1.5 MW Self-funded Table 2. DEN’s solar projects.

60 Airport Renewable Energy Projects Inventory and Case Examples DEN then participated in projects developed under the Colorado Community Solar Gardens Act. The act permits the development of grid-connected solar projects up to 2 MW, with a single large customer or subscriber using up to 40% of the power output and 60% or more purchased by smaller energy consumers. DEN is the large subscriber for six community solar gardens in Colorado: two located on airport property and four located off site. The airport has signed a contract to purchase the power for a 20-year period. The RECs that result from the project are owned by the participating utility. All six of the projects are “in front of the meter” and do not directly affect energy use at the airport. However, for the two projects located on airport prop- erty, the interconnection study assessed the capacity of the existing electricity infrastructure to accommodate additional solar generation. DEN is also participating in the Renewable*Connect program, which allows large energy consumers to purchase renewable energy from a specified off-site renewable energy generator within the same utility service area. The power is acquired through a long-term contract similar to those used for the community solar gardens; however, the utility retires the RECs generated by the projects on behalf of the customer. Under Renewable*Connect, DEN is obligated to purchase the energy for a 10-year period with an option for a second 10-year period, and DEN receives the environmental attributes (including RECs) of the energy generated. As both aviation and nonaviation development at the airport expands, DEN is planning for more renewable energy to be integrated into each development project. Though DEN does not currently have a renewable energy requirement for new development projects, it does require new airport facilities to be LEED-Gold certified, with renewable energy being one option for accruing LEED points. Projects being pursued include solar panels on top of new concourse building expansions that will serve 39 aircraft gates, as well as new surface parking areas that will support solar canopy structures. An advantage of these new projects is the fact that the electricity generated will directly serve the on-site load, behind the meter, thereby reducing the amount of power purchased from the utility. In addition, DEN will own the RECs created by the projects. 4.4.4 Project Benefits • DEN has been able to apply program opportunities to develop renewable energy at the airport, garnering maximum benefits. • DEN’s success in developing highly visible projects has helped establish the airport as a leader in the industry. Figure 45. Canopy-mounted solar over transit parking facility at Denver International Airport, CO.

Case Examples 61 4.4.5 Lessons Learned • Airports should evaluate their project objectives to understand the life of the project. Airports should also document options and decision-making processes at the beginning of the project to refer to throughout the life of the project. For example, a PPA may allow for the airport to buy the system after tax incentives have been monetized. What was the decision on evaluating that option and what were the factors that led to the decision? Also, the PPA may be for a 20-year period, but the facility may produce marketable electricity for 10 to 20 years afterward. What are the airport’s interests in the project once the PPA expires? • Each project type has its benefits. Airport-owned projects include RECs. Third-party projects include less risk. Airports should not rule out any particular project type. They should also take advantage of incentive programs and maintain a diversity of approaches. 4.5 Reverse Auction Renewable Energy Purchasing Program at Dallas/Fort Worth International Airport (DFW), TX Airport Code: DFW Technology: • Various Hub Classification: Large Project Owner: Various, airport owns the renewable RECs FAA Region: Southwest Operations Date: 2006 to 2019 4.5.1 Introduction Airports can adopt renewable energy in a variety of ways. Some respond to opportunities presented by renewable energy developers who see a project on airport property as a mutually beneficial arrangement. Other airports integrate renewable energy infrastructure into proposed capital projects such as a new parking garage. A different strategy is the purchase of renewable energy from off-site providers. Under this scenario, the electricity from the renewable energy facility does not flow directly to the airport, but the airport secures ownership of the renewable energy and all its environmental attributes produced by the off-site facility. There are advantages and disadvantages to the various approaches. When it purchases energy from an off-site facility (often through an energy broker), the airport owns the renewable energy and can apply associated ownership verification to achieve carbon emission reduction goals without initiating complicated capital projects. A disadvantage of this purchasing structure is the lack of a physical renewable energy presence at the airport, which can serve as a reminder to customers of the airport’s otherwise proven commitment to renewable energy. Dallas/Fort Worth Inter national Airport (DFW) provides a clear example of the benefits of renewable energy purchasing through a reverse auction process, as well as how an airport can increase the public visibility of its successful renewable energy program. 4.5.2 Project Details In 2006, DFW established an organizational goal to purchase a minimum of 10% of its total electricity needs from renewable sources. Because Texas is a deregulated energy market—whereby

62 Airport Renewable Energy Projects Inventory and Case Examples utilities own the transmission infrastructure and deliver the power, but the energy produced can be purchased in an open market—DFW developed a reverse auction procurement process for purchasing electricity. The airport incrementally increased the minimum level of renewables annually until 2018, when it required bidders to supply all of the purchased electricity from renewable sources. Historically, DFW has executed a contract for the winning bid for a term of 2 to 3 years. At the end of each fiscal year, DFW audits actual energy use and compares it to the amount purchased to ensure that the minimum annual renewable energy percentage is met. The purchase of 100% renewable energy through the reverse auction process has enabled DFW to achieve ACA Level 4 carbon neutral accreditation since 2016. 4.5.3 Implementation DFW works with an energy consultant who creates the framework for an online auction, inputs DFW’s energy profile and consumption requirements, notifies bidders about the auction, and administers the auction process. The winning bids from previous years are also made avail- able to current bidders for full price transparency. In addition to establishing requirements for total volume and patterns of energy use at the airport, DFW initially established a requirement that 10% of the energy delivered under the contract would be sourced and validated from a renewable energy facility. DFW also stipulated that the purchase of the renewable energy would include the energy and all associated environmental attributes, among them renewable energy RECs and carbon credits. DFW put no constraints on bidders to provide a specific renewable energy technology, thus allowing them to find and bid the lowest price possible. Because DFW consumes a substantial amount of electricity (more than 400,000 MW-h per year), it can use its buying power to enhance competition among bidders and drive down prices. Over time, DFW increased the minimum percentage of renewable energy required from the bidders. Over an 8-year period, the percentage increased from 10% to 30%, while the cost decreased by 40% by 2014, as shown in Figure 46. Though the auction encouraged intense price competition, the dramatic decrease in the price of renewable energy was primarily the result of the expanding wind energy market, particularly in West Texas, which made a substantial amount of wind-generated electricity available in the marketplace. In 2018, emboldened by the low cost of renewable energy and supported by organizational goals to maintain carbon neutrality, DFW required that bidders supply 100% of the electric- ity delivered to DFW from renewable sources. Bid prices continued to hold steady or decrease despite the requirement of 100% renewable energy. The quantity and price of energy procured are shown in Figure 46. Because 70% to 80% of DFW’s carbon footprint comes from electricity, and the remaining 20% to 30% comes from fleet and facility emissions, carbon neutrality at DFW could not be achieved by the purchase of 100% renewable energy alone. However, the purchase of renew- able energy showed how achieving carbon neutrality was feasible. Through these efforts and other innovations in the transportation sector, DFW achieved ACA carbon neutral accreditation in 2016. DFW’s strategic plan includes an ongoing commitment to purchase 100% renewable energy. DFW is also developing a solar project at a public park on airport property; the project will illustrate DFW’s level of commitment to renewable energy. 4.5.4 Project Benefits • DFW has established valid and measurable means for achieving climate mitigation goals. • The project site is highly visible, which allows for broad public recognition of the airport’s renewable energy goals.

Case Examples 63 4.5.5 Lessons Learned • It is imperative that contracts provide ownership not only of the energy but also of the envi- ronmental attributes, including RECs and carbon credits, which substantiate ownership of renewable energy values. • Because the program is not visible, as is the case for an on-site renewable energy facility, it can be complemented by either a small demonstration facility in a highly visible location or a prominent educational campaign. 4.6 Geothermal Heating and Cooling at Eastern Iowa Airport (CID), IA Figure 46. DFW’s renewable energy purchasing and cost, FY2006–FY2018. Airport Code: CID Technology: Geothermal heating and cooling Hub Classification: Small Project Owner: Airport FAA Region: Central Operations Date: September 2018 (initial phase)

64 Airport Renewable Energy Projects Inventory and Case Examples 4.6.1 Introduction Prominent renewable energy technologies such as solar PV and wind power generate renew- able electricity. Technologies that displace traditional fossil fuel–based heating and cooling have been more challenging to develop at scale; this challenge is attributable in part to the fact that heating and cooling require on-site systems (compared with large regional electric power plants), which limits market expansion. In addition, heating and cooling require a higher power density associated with thermal energy, which is most effectively produced by grid-scale tech- nologies such as biomass and geothermal. Despite these challenges, airports have successfully implemented a number of GHP systems to heat and cool large airport buildings such as terminals and concourses. These systems use the constant temperature underground of ∼50°F to cool buildings in the summer, store the displaced hot air underground, and use the stored energy to heat buildings in the winter. Eastern Iowa Airport (CID) in Cedar Rapids has developed one of the newest geothermal heating and cooling systems. This case example provides the airport industry with insight into the latest evolution and performance of such systems. 4.6.2 Project Details The project is a GHP system constructed as part of the Phase III airport terminal expansion at CID. The closed-loop system uses high-density polyethylene piping, with glycol as the transfer medium. A total of 135 wells are drilled to a depth of 300 feet. The system is sized to provide heating and cooling to Concourse B and part of Concourse C, with the potential to expand to cover all of Concourse C. Partial system operation began in September 2018. As of November 2019, 11 of the 18 GHPs are fully operational, with another five pumps installed but not yet operational and an additional two pumps still to be installed. Components of the system as it appears in the utility room of the terminal are shown in Figure 47. 4.6.3 Implementation The GHP project has been completed as part of the airport’s multiphase terminal modern- ization program. It is funded using a combination of AIP, passenger facility charge, and state development funds, but the project is also largely financed by airport capital reserves. The cost of the GHP system was $730,728. Figure 47. Pipe system for geothermal heating and cooling in terminal building of Eastern Iowa Airport.

Case Examples 65 Planning for the third phase of the terminal modernization project included working with Alliant Energy, the utility service provider, to identify and assess building system options, including alternatives to achieve sustainability objectives. An important consideration was the applicability of a rebate program for commercial customers developing new construction projects. Using this information, the airport reviewed a variety of building equipment options to maximize rebates versus the investments. As a result, Alliant’s consultant provided estimated rebate incentives based on three energy reduction strategies, which included a geothermal heating and cooling system. The geothermal system met two primary project objectives: (1) a project design based on envi- ronmental stewardship principles and (2) the best opportunity to maximize the rebate program. The airport conducted a detailed assessment of the return on investment for the GHP on the basis of the change in power costs (i.e., savings) versus the investment. CID used an average utility rate of between $0.70 and $0.85 per square foot for traditional heating and cooling and compared that to $0.50 and $0.65 per square foot for the geothermal installation. The savings were then compared to the cost of the system to calculate an expected payback period. The airport predicted that the cost of geothermal versus traditional boiler-feed heat pumps showed a 6-to-9-year return on investment, which also accounted for the cost of a 240-kW solar project on the terminal roof but did not take into account a $69,546 rebate from the new commercial construction program with Alliant Energy. The geothermal system came with a 1-year warranty from the installer. The system life is expected to be 50 years. As the building and the geothermal system have been in various states of construction, testing, and operation over the past year, an actual cost comparison will need to wait until the complete installation is online in the spring of 2020. 4.6.4 Project Benefits • Lower long-term heating and cooling costs result in lower operating costs for the airport’s tenants. 4.6.5 Lessons Learned • CID recommends that additional investment be made during site investigation, including completing a dozen or more test borings in the wellfield to ensure the collection of consistent geotechnical data. CID conducted only a few test wells, which produced data insufficient for project design. The airport ended up spending an additional $97,000 to modify the design and ensure that the facility was balanced correctly. • The rebates offered by the energy provider represented a significant opportunity to demonstrate cost-effectiveness. • CID made some small but valuable investments to the design to accommodate the cost-effective future expansion of the system. 4.7 Biomass Boiler at Ketchikan International Airport (KTN), AK Airport Code: KTN Technology: Biomass with wood waste Hub Classification: Nonhub Project Owner: Airport FAA Region: Alaska Operations Date: 2016

66 Airport Renewable Energy Projects Inventory and Case Examples 4.7.1 Introduction The opportunity to generate renewable energy depends primarily on geography and climate. For example, wind farms will be most cost-effective when constructed in windy regions. In the United States, such regions include the Great Plains and those offshore of the East Coast. Similarly, hydropower is greatest in the West, where rivers flow from the Rocky Mountains to the Pacific Ocean. In Ketchikan, Alaska, woody biomass is most plentiful as a byproduct of the forestry industry. For this reason, the Borough of Ketchikan installed a biomass boiling heating plant at Ketchikan International Airport (KTN) to heat the airport terminal. 4.7.2 Project Details The biomass boiler is rated at 500 MBH (or 500,000 Btu-hr), sufficient for providing 90% to 95% of the airport’s heating needs. For redundancy purposes, the airport requires backup power, which is provided by an oil unit. In addition to its availability in an emergency, the oil unit is also activated to provide peak power on the coldest days, which accounts for the additional 5% to 10% of energy generation. KTN made a purposeful decision not to oversize the biomass boiler, enhancing both efficiency and operational life. A 700-gallon water tank was also installed with the oil boiler to provide thermal energy storage, which augments the boiler’s overall efficiency. An automated silo with a storage capacity of 30 tons of wood pellets was installed adjacent to the boiler building, supplying on-demand delivery when the amount of wood pellets reaches a specific level. The boiler system is located inside an old fish storage building that has been retrofitted for its new purpose. The building includes a large glass viewing window with an educational display that allows visitors to see the boiler and learn about its operations. 4.7.3 Implementation KTN’s oil-fired boiler was 45 years old and in need of replacement. A bid was released for a new, more efficient oil-fired boiler system in 2010, with responses to the bid higher than expected. The airport staff learned of recent biomass boiler installations elsewhere in Alaska that, in addition to generating heat, also used local renewable resources. Staff set up visits at existing biomass installations to learn more about recent operational experiences. Airport staff discovered that the cost of a biomass boiler was similar to that of an oil-fired boiler and that state grants could potentially reduce the overall cost to the borough. The borough initially received a grant from the U.S. Department of Agriculture to conduct a feasibility study of a biomass boiler. This study confirmed the cost-effectiveness of biomass and defined the system requirements for the project. Then, with additional grant commitments from the Alaska Energy Authority, the borough proceeded with design and construction. The system became operational in fall 2016. The boiler building and feedstock silo are shown in Figure 48. 4.7.4 Project Benefits • Operating costs of this biomass heating system are $30,000 per year, compared with $70,000 per year for the previous oil-fueled system. • Combustion of the regional woody biomass (wood waste and sawmill residue) reduces GHG emissions by 54% when compared with the burning of oil for fuel. 4.7.5 Lessons Learned • The airport thoroughly researched the experiences of other in-state installations, which helped it to better understand the advantages of a biomass boiler heating system, specifically as it would operate in Alaska.

Case Examples 67 • Previous installations had incomplete combustion, which could be resolved by purchasing different equipment and working with an experienced engineering team. • The airport also purchased the boiler and silo separately, this ensuring that KTN had control in selection of the most critical components and bid engineering and installation. 4.8 Geothermal Lake Plate Cooling System at Nashville International Airport (BNA), TN Figure 48. Biomass boiler building with feedstock silo at Ketchikan International Airport, AK. Airport Code: BNA Technology: Geothermal cooling Hub Classification: Medium Project Owner: Airport FAA Region: Southern Operations Date: February 2016 4.8.1 Introduction Airports have different characteristics that require individualized assessment of problems and solutions. Some issues can be grouped by airport size, while others may be defined by geography and climate. In other cases, an airport may have specific landforms and uses that reveal unique challenges and opportunities. Such was the case when the Metropolitan Nashville Airport Authority (MNAA) acquired a former rock quarry as part of an airport expansion project at Nashville International Airport (BNA) three decades ago. Once thought to be only a potential hazard to aviation activities, the quarry has become the central component of BNA’s geothermal lake plate cooling system, the largest in North America. 4.8.2 Project Details The purpose of the project was to utilize cold water deep in the rock quarry to provide a constant source of cooling for the airport. The MNAA sponsored the construction of a closed-loop pipe system connecting the airport terminal and the rock quarry. Water from the terminal is pumped to the quarry, which holds about 1.5 billion gallons of water, where geothermal heat exchangers submerged in the quarry cool the water to about 63°F. The cooled water is pumped back to the

68 Airport Renewable Energy Projects Inventory and Case Examples terminal’s central utility plant and, as prechilled water, reduces significantly the energy required to cool the terminal. Once the cooling has been accomplished, warmer water of about 79°F is circulated back to the quarry, repeating the cycle. The system includes 10,000 feet of 20-inch pipe and 11 lake plate heat exchangers, each about the size of a large car, submerged more than 50 feet below the quarry surface. The pipe crosses under an active runway, taxiway, state highway, and airport service road before climbing the terminal wall and entering the central utility plant. As a closed-loop system, the water in the pipes never mixes with the water in the quarry. MNAA used this opportunity to upgrade the chillers in the terminal and to reprogram the building’s heat and cooling system to maximize cost savings and efficiency. 4.8.3 Implementation In 2009, a comprehensive energy study was conducted on all MNAA-operated facilities. The study determined that the quarry might be suitable as a source of geothermal cooling. In 2012, a preliminary engineering evaluation was conducted to assess the feasibility and design of a large- scale geothermal system. A conceptual plan for the system was completed by the end of 2013. The project was included in the airport’s capital program for 2015 at $10.5 million. BNA applied for FAA AIP funding and received a $3.6 million grant for the project under its energy efficiency grants in 2014. Other sources of funding included $1.3 million from the state of Tennessee and $1.3 million from airport revenues. The remaining amount would be financed by energy savings- backed bonds. After the MNAA filed a short-form environmental assessment, FAA issued a Finding of No Significant Impact to approve the project. MNAA procured a design-builder through advertise- ment and selection according to FAA procurement requirements. The executed design-build contract included a guaranteed maximum price and guaranteed minimum annual reductions in energy and water (3,029,983 kW-h and 30 million gallons, respectively). The contract included a measurement and verification plan based on field measurements for assessing compliance with the contract guarantees, as well as penalties if the contractor did not meet the guaranteed savings, and specified a remedy period for making corrections. Project construction began in April 2015. Construction activity is shown in Figure 49. MNAA implemented the new system in Figure 49. Construction of geothermal lake plate project at Nashville International Airport, TN.

Case Examples 69 February 2016. The project team focused on optimizing the system through the first 6 months, which was critical to ensuring enhanced system performance. MNAA owns the project. The facility has a payback period of less than 10 years and a 50-year minimum service life. 4.8.4 Project Benefits • The project has resulted in more than $500,000 in electricity savings annually, which was greater than forecasted. • It also saves 20 million gallons of water for the cooling system and 10 million gallons of water used for irrigation. • The pipes had to cross runways and taxiways. Extra electrical and communications conduits were included to provide for future opportunities. Concrete repairs and painting were con- ducted during the closure. 4.8.5 Lessons Learned • Design-build was an excellent delivery method for the project because of the nature of the job. The contract design was based on performance specifications, which gave the design-build contractor the control and flexibility necessary to achieve project performance goals. • The switch to the new system was scheduled for the middle of a winter night in an effort to reduce the impact to the airport of several hours without a cooling system. However, switch- ing to such a system at any time is challenging given that the airport needs to be operational 24 hours a day. MNAA mitigated risks by developing a detailed switchover plan, in 15-minute increments, with specific points-of-no-return and exit opportunities. A backup crew was prepared to bring the old system back online at a moment’s notice. • The irrigation component, which is separate from the geothermal system, was added to the project to access on-site water and reduce water purchasing. 4.9 On-Site Energy Management Program with Solar and Battery Storage at San Diego International Airport (SAN), CA Airport Code: SAN Technology: Battery storage, solar PV (roof-mounted, canopy-mounted) Hub Classification: Large Project Owner: Airport (battery) and private third party (solar) FAA Region: Western-Pacific Operations Date: 2016 to present 4.9.1 Introduction Renewable energy produces emissions-free, carbon neutral power, but only when the renew- able resources can be accessed. For solar PV energy, power is produced during the day but not at night. For wind power, energy is produced when the wind is blowing but not when it is calm. Thus, because of its intermittent nature, renewable energy needs to be coupled with nonrenewable sources (e.g., fossil fuels) to provide a baseload. However, recent advances in the development of cost-effective utility-scale battery storage offer an alternative whereby renewable energy can be generated and stored for use at a later time.

70 Airport Renewable Energy Projects Inventory and Case Examples Energy storage technology allows for enhanced control over when on-site energy is consumed, which in turn allows the user to reduce grid purchases at times of peak demand prices. An energy storage system also supports the key components of an independent microgrid, with on-site generation controlled and energy dispatched in a consistent manner to feed on-site demand in the microgrid when it is disconnected from the regional grid. For these reasons, the San Diego County Regional Airport Authority (Airport Authority) has recently implemented a battery energy storage system (BESS) project at San Diego International Airport (SAN). The BESS, when combined with other improvements, will stabilize and dispatch electricity to reduce power costs; it will also serve as a building block for the development of a microgrid electricity distribution system. 4.9.2 Project Details The project is a BESS composed of a 2 MW/4 MW-h lithium-ion battery, which is supported by GridSynergy, a software-driven energy storage solution. GridSynergy’s cloud-based software will draw on data showing past and present energy-generation and usage at the airport to calcu- late optimal charge and discharge cycles for the lithium-ion batteries. GridSynergy will address the operational needs of the airport’s energy system over the next 10 years. SAN’s energy usage is complex because it includes 5.5 MW of solar PV energy, which serves about 15% of the airport’s energy needs. The solar PV project includes a 2.2-MW roof-mounted facility on top of Terminal 2, a 2.2-MW canopy-mounted facility over the adjacent Terminal 2 surface parking lot, and a 1.1-MW canopy-mounted facility over surface parking at the north- side economy parking area. Elements of the electricity-generation and distribution system are shown in Figure 50. The Airport Authority purchases the power generated by the facility, which is owned and operated by a private entity through a PPA in which the Airport Authority retains Figure 50. Microgrid infrastructure with solar PV sites at San Diego International Airport, CA.

Case Examples 71 all RECs generated from the systems. The power output from the solar facilities varies depending on time of day and weather conditions; the battery system captures some solar output and releases it later in an effort to distribute the power more consistently. 4.9.3 Implementation The Airport Authority initially prepared extensive energy modeling to analyze the airport’s load profile during planning for the Green Build Terminal 2 project. The modeling assessed the existing power use, the forecasted future power use based on growth assumptions, and the potential gap to illustrate energy needs. The study highlighted the risk of prolonged electrical outages attributable to the airport terminals’ single-circuit connection to the electrical grid without redundancy. Electrical infrastructure improvements projects completed in 2009 resolved this issue by creating three circuits to deliver power to the airport terminals and, subsequently, by establishing individual loops to serve specific areas of the airport. These upgrades also enabled the development of the Green Build terminal, which was completed in 2013. As a result of these improvements, the airport is supported by a 12-kV electrical service and distribution system that includes five loops serving various parts of the airport. Two primary circuits located in the airport’s main vault supply airport power from the grid, and one alternate is available if a primary circuit is lost. Controls in the network allow the Airport Authority to direct power to specific loads as necessary. Informed by both (1) the existing energy load and infrastructure and (2) the energy needs forecasts, the Airport Authority began to develop a plan for managing energy supply and costs. In considering the airport’s projected energy demand, the Airport Authority planned for the development of on-site electricity generation provided by solar PV. With significant land limi- tations, the best siting option was on existing buildings and on new canopy structures located over surface parking areas. By 2017, 5.5 MW of on-site solar PV had been developed. Concurrent with these efforts, the airport prepared in 2016 and 2017 a strategic energy plan that summarized the efficiency, generation, and infrastructure improvements; developed organizational goals for energy management; and outlined a roadmap to meet conservation, environmental, resiliency, cost-containment, and industry leadership goals. As the solar generation potential was significant and its contribution to the local grid would vary widely with time of day and weather conditions, the Airport Authority installed a supervisory control and data acquisition (SCADA) system to monitor the airport’s overall energy use. It includes sensors throughout the airport’s grid that measure voltage, current, which breakers are open, and where there is or is not power. The SCADA system is programmed to automatically shed electricity load in the event of a primary circuit fault to ensure that critical airport loads are continuously served. The Airport Authority recently installed a 2 MW/4 MW-h lithium-ion BESS with software controls that became operational at the end of May 2020. The airport has two primary objectives for implementing the system. First, the BESS will decrease the amount of energy the airport purchases from the utility during peak demand by deploying energy stored in the BESS during those periods. Electricity prices are highest during peak demand, and energy purchased during peak periods currently represents about 40% of the airport’s monthly energy bill. Second, the system will provide greater opportunity to consolidate energy loads and leverage more capacity for solar PV and other on-site renewable energy sources planned for the future. In addition, the 12-kV system provides the airport with greater control over its maintenance programs by allowing SAN to manage power loads from different sources and to proactively pursue maintenance before system failures occur. Though the BESS theoretically could be used to store energy for use in the event of a grid outage, it will not be programmed to provide this function because the battery size is small relative to the airport’s overall energy demand. However, the BESS is consistent with SAN’s long-term goal to add storage and energy generation to increase resiliency and reduce associated risks to operations.

72 Airport Renewable Energy Projects Inventory and Case Examples 4.9.4 Project Benefits • Reduced overall electrical utility costs: – Demand costs are reduced through consolidation of small meters and conjunctive billing of the main circuits. – Increased capacity for solar PV and battery storage helps the airport produce and use power at a lower, more effective rate. • Redundancy: – The entire airport can be powered by either of two primary circuits. – The SCADA system has programmed the alternate circuit to pick up half the airport loads if one primary circuit is lost. • Resiliency and business continuity: – Primaries do not share the same manhole, and the Airport Authority’s emergency circuits do not share the same manhole with any primary or secondary airport circuit. – Faults will be isolated by automatic protections and power will be restored to remaining loads automatically through SCADA logic and automatic switching. – In an effort to protect priority loads, the system is programmed to shed loads if at capacity. – San Diego Gas and Electric has enabled the close transition (paralleling circuits) function to shift loads with no power interruptions as needed for maintenance and shift lineups. – SAN has control over the maintenance program of critical 12-kV and tertiary electrical gear. • Increased flexibility: – SAN relies only minimally on the utility for outage needs during projects and maintenance. – The SCADA system allows for monitoring of and reporting on the system, subsystem, and loads. 4.9.5 Lessons Learned • A BESS requires a solid plan that considers future growth, changing technology, organiza- tional goals, and a complex energy market. • It also requires a robust maintenance program and capable technicians, as well as adequate management once in operation. 4.10 Community Solar Project at St. Louis-Lambert International Airport (STL), MO Airport Code: STL Technology: Solar PV (ground-mounted) Hub Classification: Medium Project Owner: Third-party utility FAA Region: Central Operations Date: 2019 4.10.1 Introduction Proponents of renewable energy are constructing solar PV projects in a variety of models to serve an array of interests created by federal and state energy initiatives. One such model is the community solar project, which encourages developers to finance project costs by securing contracts with small and large energy users who voluntarily purchase renewable power from the facility at a prescribed electricity rate. In some recent examples, airports have partnered with solar developers on community solar projects by offering land for development and either participating as a member of the community to buy the solar energy produced or simply receiving

Case Examples 73 a lease payment as an airport revenue source. The Ameren Missouri Lambert Community Solar Center is an example of a recently constructed community solar project. 4.10.2 Project Details The project is a 1-MW ground-mounted solar PV system built on underused airport land north of the primary airport facilities. It includes three subarrays with 2,800 solar modules and associated equipment. It uses a fixed tilt design with no tracking or other moving parts. In this design, metal pilings support racking structures on which the solar modules are mounted. The amount of power produced is sufficient to supply about 100 homes. The facility is owned by Ameren, the electric utility serving the region, which has a lease with the City of St. Louis to own and operate the solar facility on airport land. The electricity generated by the system is transmitted directly into the regional electrical grid, which is owned and operated by Ameren. However, the project is configured as a community solar project whereby Ameren’s resi- dential and small retail customers can sign up to purchase the solar power generated by the facility. 4.10.3 Implementation Under the Missouri Renewable Energy Standard, utilities operating in the state must supply a minimum of 15% of total electricity from renewable energy sources and 2% from solar power. To meet this requirement, Ameren sought to partner with the City of St. Louis on a demonstration solar project. However, limited land within the St. Louis city limits is available to accommodate a 10-acre project, as was initially considered. Ameren had been working successfully with St. Louis-Lambert International Airport (STL) on an energy efficiency program that ultimately received an award from the governor. Given the airport’s potential availability of land and existing infrastructure to connect to the electrical grid, STL became a logical partner to help Ameren develop a solar project. Ameren and STL investigated six potential sites on airport property. The preferred site, which was subsequently developed, is located at the intersection of Missouri Bottom Road and North Lindbergh Avenue, bordered by railroad tracks, and is in the extended centerline of Runway 12L/30R. The site was optimal for a solar project because it is adjacent to the existing 34-kV electricity line, allowing for ease of interconnection. The site also has limited development potential for other uses because of (1) aircraft noise during takeoff and landing and (2) topography and access constraints. A picture of the project is provided in Figure 51. Figure 51. Solar project located in undevelopable area of St. Louis-Lambert International Airport, MO.

74 Airport Renewable Energy Projects Inventory and Case Examples When STL engaged FAA in project approval, the airport determined that preparing and funding the approval process for a 10-acre project site would be prohibitive. It worked with Ameren to reduce the footprint below the 3-acre threshold that would allow for streamlined FAA approval under NEPA. STL considered the options of buying the electricity from a solar facility and of receiving a lease payment as a landlord. STL’s existing electricity costs are very low, which make it difficult to justify paying more for solar electricity. STL chose to execute a lease agreement whereby it receives $4,000 per year for a 20-year period. This arrangement also fit with Ameren’s project objectives and allowed the utility to offer the electricity to residential and small retail subscribers. 4.10.4 Project Benefits • The climate mitigation benefit is estimated to be a reduction of 2,145,774 pounds of carbon dioxide per year. • The project site is highly visible, which allows for broad public recognition of the airport’s renewable energy goals. 4.10.5 Lessons Learned • The project’s success depended on a project champion on the airport staff and a committed partner at the utility to push the project forward. • The permitting and approval process was more complicated and expensive than the airport or the utility had anticipated.