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9 FIGURE 7 Transmission lines at sunset (courtesy: HMMH). making wet cooling a more efficient heat transfer mechanism. FIGURE 6 Power plant (courtesy: U.S. EPA website). However, owing to concerns about water scarcity, new power plants are often required to assess the feasibility of dry cooling. tricity (see Figure 6). Because the fuel they run on is always available (unlike renewable sources), these plants provide base Electrical Transmission Infrastructure load electricity to the grid. Older plants operate with coal and oil, whereas newer plants typically utilize natural gas or bio- Transmission lines consist of towers and high-voltage lines fuels, which comply with modern environmental regulations. necessary for carrying power produced at energy-generation facilities across distances to areas where the electricity is con- Some smaller capacity plants, known as peakers, are being sumed (see Figure 7). Typically, new transmission lines are developed that can start up quickly during periods of peak built to deliver electricity to locations where the lines can energy consumption. Peakers typically fire up during the sum- be integrated into the existing regional and local electrical mer months when air conditioners are operating or in the win- network. The height of the towers can vary; however, taller ter during periods of extreme cold when heaters are operating. towers generally mean that they are fewer in number, which Peaker plants are less efficient than base load plants and typi- tends to be more economical. Tower height and distance fol- cally have higher exhaust velocities and temperatures because low industry-published design guidelines (ASCE 1997; IEC they lack a heat recovery steam generator. This type of gener- 2003). Conventional towers are approximately 150 ft high. ator extracts heat in the flue gas producing cooler exhaust tem- Because many new energy-generation technologies are located peratures and lower exit velocities. Because peaker plants can in remote areas, transmission lines are an important compo- be designed with shorter stacks, they may not trigger an air- nent of the energy project. space review. In addition, the shorter stack produces a greater dispersion of the plume lower to the ground. When located near an airport, these high temperatures and exhaust velocities ASSESSING IMPACTS can create turbulence for aircraft passing through the plume. This section describes information available for assessing impact. First, the definition of navigable airspace is provided Traditional power plants require a cooling system to cool to establish the geographic area where impacts can be pro- the exhaust steam for reuse. Cooling towers release heat pro- duced. Second, the forum for reviewing potential impacts duced in the steam generation process and transfer it back to (i.e., the regulatory process) is summarized to provide an under- the environment, either to the water or air. There are two types standing of what processes are requiring the impact studies. of cooling towers: evaporative wet cooling and dry cooling. Third, the community that is impacted by proposed energy The mechanics of the systems vary; however, the end process projects is described. And fourth, the types of information is the same, to remove heat and cool water for reuse. They that have been generated directly and indirectly as the result can use either evaporation to remove the excess heat and cool of regulatory reviews are summarized providing a snapshot the liquid (wet cooled) or rely on air to cool the liquid to the of the current knowledge base. ambient temperature (i.e., air cooled). Evaporative wet cool- ing systems release moisture into the air to transfer heat. Air- cooled condensers transfer heat to the ambient air not unlike Defining Airspace an automobile radiator. The air-cooled condenser maximizes surface area for transfer of the heated steam exhaust to the sur- One of the FAA prime objectives authorized by statute is to rounding air and fans blow the heated air skyward. Because ensure the safety of air navigation and the efficient utilization water is denser than air its heat carrying capacity is greater, of navigable airspace by aircraft (FAA 2008a). Under Title

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10 49 of the United States Code, Section 40103(a)(1), "the United physical, electromagnetic, and line-of-sight interference on States Government has exclusive sovereignty over airspace of navigation, communications, radar, and control system facil- the United States." The National Airspace System is a limited ities; and airport traffic and service capacity (FAA 2008a). resource. New structures and activities that infringe on air- space are continuously proposed. It is the FAA's responsi- The FAA has established clear thresholds for defining bility to evaluate the significance of each proposal. When airspace and created a notification process for requiring conflicts arise concerning a structure being studied, the FAA project proponents to notify the FAA of projects that may may advocate the need for conserving the airspace for aircraft; impact airspace. The definition of airspace is described in preserving the integrity of the National Airspace System; and the section Physical Penetration of Airspace in this chapter. protecting air navigation facilities from encroachments such The process for evaluating potential hazards is described in as physical penetrations, electromagnetic interference, and Order JO 7400.2G, Procedures for Handling Airspace Mat- visual impairments that would preclude normal operation. ters (FAA 2008a). For off-airport projects, proponents file a ACRP recently funded a principal reference for understand- Form 7460 with the FAA Office of Obstruction Evaluation/ ing airspace review (LeighFisher 2010). Airport Airspace Analysis (OE/AAA). The OE/AAA is a par- ticular office under FAA's Air Traffic Organization whose 14 CFR Part 77 provides the following regulatory guidance responsibility it is to coordinate the FAA's review of poten- for FAA's authority relative to airspace protection: tial hazards to air navigation. (1) establishes standards for determining obstructions to Regulatory Review Processes navigable airspace (2) sets forth the requirements for notice of certain pro- The energy technologies discussed in this report typically posed construction or alteration trigger federal, state, regional, and local permitting processes (3) provides for aeronautical studies of obstructions to before being constructed. Under conventional project permit- air navigation to determine their effect on the safe ting, applications are filed, hearings are convened, presenta- and efficient use of airspace tions are made, public input provided, and permit decisions (4) provides for public hearings on the hazardous effect of rendered based on existing laws and regulations. Through proposed construction or alteration on air navigation. this process, impact analyses are generated. In some cases, independent government studies may be initiated where the Furthermore, "[t]he standards established in determining permitting process has not adequately resolved the issue. The obstructions to air navigation are used by the Administrator primary regulatory processes associated with energy tech- to impose requirements for public notice of the construction nologies and impacts on aviation are described here. or alteration of any structure where notice will promote air safety. Notices are used to provide the basis for determina- tions of possible hazardous effect of the proposed construc- OE/AAA tion or alteration on air navigation." The FAA's OE/AAA Division undertakes aeronautical studies Airspace, as defined by federal regulation, begins at a to assess the potential impacts of a project on air navigation. height of 200 ft above ground level and extends upward. In It distributes the notice to representatives of the various FAA closer proximity to airports and military installations, where lines of business, including airports, technical operations, aircraft approach and descend, the height of airspace is less services, frequency management, flight standards, flight pro- than 200 ft. The FAA regulations refer to the invisible bound- cedures office, and military representatives. Each division aries that demarcate airspace as imaginary surfaces. These has the responsibility of providing comments on the potential imaginary surfaces extend out from the runway in a manner impacts of a proposal on its area of authority and expertise. that reflects where aircraft are likely to fly while also accom- As an example, air traffic personnel is responsible for identi- modating unforeseen aircraft maneuvers. The height above the fying whether the structure impinges on airspace; assessing ground of the imaginary surface is lowest near the runway and effect on existing and proposed aeronautic operations, traffic increases at distance from the runway. State and local author- control procedures, and traffic patterns; providing comment ities have attempted to regulate areas below 200 ft as airspace on mitigation opportunities including marking and lighting; as a result of localized concerns about the impact of shorter identifying when negotiations with sponsors are necessary; structures on aviation. determining when circulation is necessary and coordinating that process; collecting all comments; and issuing the deter- The FAA is responsible for conducting obstruction evalu- mination. Technical operations staff identifies electromag- ations to determine potential impacts on airspace. Specifically, netic and/or physical effects including the effect of sunlight the evaluation may consider the effects on public use and mil- and reflections on air navigation and communication facilities. itary airports and aeronautical facilities; visual flight rule and instrument flight rule aeronautical departures, arrivals, and Upon completing the aeronautical study and obtaining en route operations, procedures, and minimum flight altitudes; input from the various divisions and organizations involved

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11 in the review, the OE/AAA issues a hazard determination communication, 2010). This is much in contrast to projects sub- on the proposed structure or activity. If the project will not ject to NEPA review that provide a forum for early comment impact aviation, the OE/AAA will issue a Determination of from all agencies including the FAA. No Hazard. If an impact is identified, the OE/AAA will issue a Determination of Presumed Hazard, the reason for the Recognizing the importance of the NEPA review for avi- hazard, and changes that could be made to avoid the hazard. ation impact issues, the Department of Defense (DoD) and Unless the applicant agrees to the changes in writing, the Bureau of Land Management (BLM) have executed a mem- Notice of Presumed Hazard will be reissued as a Determi- orandum of agreement (MOA) to evaluate and resolve con- nation of Hazard as the FAA's final determination on the flicts associated with projects proposed on BLM land. This matter. The determination, however, is not a permit enforce- is of consequence because the BLM has been issuing leases able by law but is instead part of a notification process to for energy projects on federal lands. Although the BLM is identify potential hazards to aviation, require marking and already obligated under NEPA to solicit input from other lighting of potential hazards to minimize potential risk to avi- federal agencies, the MOA provides the aviation community ation, and update aeronautical charts and flight procedures and the military with an early notification process. Therefore, for pilots to avoid the hazard. In reality, however, a hazard when the BLM initiates a process to lease land to an energy determination is sufficient enough to deter project financing development company, the DoD is one of the parties notified and underwriting owing to the potential liability associated about the project and can provide comment on facilities and with the determination. As an example, most utility-scale wind activities and potential adverse impacts. Although the FAA turbines are greater than 200 ft in height and are subject to is not party to the MOA, the BLM is obligated to notify the airspace review by the OE/AAA. The receipt of a hazard FAA under NEPA. determination from the FAA for a proposed wind turbine is considered by project developers to be a fatal flaw, thereby In April and May of 2010 a military planning group com- negating the project. prised of representatives from the Army, Navy, and Air Force, commented to the BLM that six wind farm projects in the Mojave Desert near Barstow, California, could negatively National Environmental Policy Act impact military activities in the area. The DoD reported that the projects will constrain flight operations, interfere with Projects conducted by federal agencies, hosted on federal radar, and increase the chance of collisions. Those comments lands, financed with federal funds, or requiring a federal per- prompted one of the developers who had proposed three of mit are subject to review under the National Environmental the six projects to withdraw its applications for approval. Policy Act (NEPA). Under NEPA, the lead federal agency responsible for the federal action facilitates a broad public review of the project that includes a variety of environmen- State and Regional Regulatory Review tal analyses such as potential impacts on transportation sys- tems. Applicants file reports and analyses that form the basis State and regional regulatory authorities may facilitate broad of a decision (known as an Environmental Impact Statement environmental reviews of projects similar to those completed or EIS) by the lead agency regarding the project's compli- under NEPA. These reviews authorized under state legisla- ance with NEPA. Because the NEPA review is broad, it typ- tion (sometimes referred to as "little NEPAs") are coordi- ically catches all the possible environmental issues that a nated by state environmental agencies and/or state energy project might affect. EISs are rich with analyses of potential commissions. Some state and regional regulatory reviews impacts of projects on airports and aviation. require that FAA notification be secured as part of a land use permit. This was the case with the Shepherd Flats Wind Farm As noted earlier, the FAA Hazard Determination is not a in the Columbia River Region of Washington State. permit and therefore is not considered a federal action for the purposes of NEPA. It alone cannot trigger a NEPA review. Some friction between the different levels of government As a result, projects with potential aviation impacts will not that are considering the potential impacts of energy projects on be subject to a NEPA review unless there is another issue that aviation has been reported. Local authorities see local issues triggers NEPA. and are concerned that state and federal authorities do not rec- ognize them. Meanwhile, decisions by state energy authorities Furthermore, project developers may not consider prepar- may override local laws, regulations, ordinances, and standards ing a Form 7460 for an airspace review until the latter stages owing to the overall public good in developing energy proj- of the regulatory process unless their project is located close ects (CEC 2010a). Projects proposed on federal land may be to an airport and aviation issues are raised in the broader per- exempt from local and county land use regulations further leav- mitting context. This has been a common occurrence that has ing the local voice unheard (Riverside County 2010). Finally, put the FAA in the challenging position of issuing a hazard the FAA has made it clear that airspace cannot be disparately determination for a project that has otherwise substantially pro- defined and regulated across the country, making Part 77 the gressed and achieved regulatory approvals (Globa, personal basis for all airspace regulation decisions (Whitlow 2009).