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4 The U.S. Department of Energy (DOE) has released the following definition to describe a microgrid: âA microgrid is a group of interconnected loads and distributed energy resources (DER) within clearly defined electrical boundaries that acts as a single controllable entity with respect to the [distribution] grid. A microgrid can connect and disconnect from the grid to enable it to operate in both grid-connected or island modeâ (DOE 2018). The purpose of this study is to compile information on microgrid funding mechanisms, oppor- tunities and challenges, operational issues, design methodologies, the intricacies of working with utilities, and lessons learned, which will help inform airport and public transit entities. This report is structured to first introduce the background and evolution of microgrid technologies, then provide a discussion of the benefits and opportunities, barriers, and considerations. Costs, cost savings, revenue streams, funding, and ownership structures are then presented, and several relevant existing projects are described. Airports and public transit are critical infrastructure and major energy users requiring resilient and reliable power. These are some of the characteristics of a facility that would typi- cally be considered a good candidate for discussing the opportunities of developing a microgrid. Given a lack of established examples, opportunities, benefits, and barriers generally are not widely understood in the industry. Even less well understood are the complex costs, funding mechanisms, and ownership structures that are crucial to evaluating feasibility. This synthesis report presents a literature review on the emergence of microgrids, the state of practice for microgrids, their merits and advantages/constraints, main components, and appli- cations, and provides insight into the following questions: ⢠Resiliency and reliability are known key drivers for microgrids for the aviation and public transit sectors. What is the frequency of power outages? What is the future risk of outage due to utility grid reliability issues, natural disasters, terrorism, and so forth? What is the cost of downtime or service interruption? ⢠Aside from reliability and resiliency, what are the needs and benefits of microgrids at airports and in public transit facilities? ⢠What are the challenges for airports and public transit entities? What are the knowledge gaps? What are the policy, regulatory, and utility cooperation gaps? What are the paths forward in these areas? ⢠What are the costs associated with microgrid equipment and ongoing operations and main- tenance (O&M)? What are the potential cost savings and revenue streams? ⢠What funding mechanisms are available? What makes each of them successful? Which would be most relevant to airport and public transit entities? What is the value of resil- ience, reliability, operational savings, and other measures (such as carbon reduction) that microgrids can offer? C H A P T E R 1 Introduction
Introduction 5 This synthesis report compiles information about microgrids and their implementation. It discusses barriers and challenges to implementation, as well as methods utilities have used to promote, foster, or support development. Primarily intended to inform airports and public transit entities that may consider establishing a microgrid, the report also will be useful to energy managers, engineers, planners, decision makers, and utilities. Coordination with the utility can be one of the greatest opportunities and challenges to microgrid installation. When done successfully, such coordination can unlock many opportu- nities. The utility can be a valuable partner and in many cases also can benefit from the instal- lation of a microgrid. The macrogrid is essential to a successful, operational microgrid and the utility connection remains an integral part of a resilient and reliable islandable power system. The relationship between the two systems can and ought to be mutually beneficial. When referring to microgrids for airports, this report considers facilities such as terminals, ground access and parking, air trains, runways and taxiways, navigational aids, and other powered elements of the campus. When referring to microgrids for transit entities the report considers rail, light rail, and buses. Microgrids can be applied to both buildings and transit operations. Public transit entities could benefit from service to safety systems, station buildings and offices, ticketing machines, maintenance facilities, stabling yards/depots, gates, security, electrified rail/traction power, track lighting, escalators/elevators, park-and-ride lighting, moveable bridges, intermodal emergency transport, and electric vehicle charging. In addition to compiling existing information via a literature review, the research team also gathered information on industry experience directly from airports and public transit entities through targeted surveys, interviews, and panel discussions. Panel discussions were held with 10 organizations (including U.S. airports, public transit entities, and other microgrid opera- tors) to gather information relating to industry experiences with microgrids and the need for resilient, reliable power. Figure 1 shows an indicative microgrid design process. Timeframes and sequences of tasks will vary from project to project, and some stages may overlap or be iterative and revisited at several points. In general, however, Figure 1 summarizes the complex process to progress a microgrid project from concept to operational. The process begins with an internal discussion around goals and objectives to frame the projectâs needs and requirements. The utility is engaged early in order to take advantage of collaboration opportunities and determine mutual benefits. Outside consultants may be useful to study feasibility and to present ownership and funding options. The design, permitting, and construction stages may be managed in different ways depending on the chosen project ownership model. Commissioning, measurement and verifica- tion, and ongoing O&M ensure that systems are installed as designed and continue operating as intended for the life of the installation.
6 Microgrids and Their Application for Airports and Public Transit Figure 1. Elements for microgrid realization (Arup 2017).
