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46 Airports and public transit entities are a relatively new market segment for microgrid adop- tion. With less knowledge and experience in microgrid methods and technologies, the two industries want to know what benefits and advantages apply to them, what are the barriers, and what financial and ownership models make a successful business case. This synthesis has sought to address these questions by gathering microgrid facts, owner motivations, success stories, and examples of strong business cases. With the dramatic cost declines in DER in recent years, microgrids have expanded beyond their traditional role as power sources for remote locations. Now, with an emphasis on microgrids for resilience and with advanced microgrid controllers, microgrids have emerged as a revenue stream for utility customers. Additional benefits to a microgrid owner can include lower emissions via maximized utiliza- tion of on-site renewable energy generation; improved power quality; energy use cost reductions; and significant savings by avoiding facility downtime. Not all of these benefits are in synergy with one another, but the customizable nature of a microgrid means priority goals can be addressed with a unique solution. Microgrids present several opportunities for the airport and public transit sector in par- ticular. Factors such as the physical space availability, electrical system scale, and on-site elec- trical system experts make airport and public transit facilities attractive sites for microgrid implementation. In addition to the utility integration barriers that affect all microgrid market segments, air- ports and public transit entities have intensive power demand, extensive security requirements, and considerable construction constraints. A further impediment is the lack of successful exist- ing projects to demonstrate effective practices and economic viability for the particularities of airport and transit operations. Moreover, microgrid feasibility depends on many varying fac- tors and a success story from one location may not be replicable at another location because of external factors such as state policy, local natural gas and electricity tariffs, or solar resource availability. The costs associated with developing a microgrid depend heavily on the systems used. Estab- lished technologies such as solar panels and natural gas turbines are less expensive technologies compared with emerging technologies such as battery storage and fuel cells. The up-front costs of all components are reducing rapidly as adoption increases. DER will generally be the big- gest ticket item of a microgrid, so existing systems and subsidies play a large role in capital cost reduction. Significant energy cost savings can be achieved through avoided grid electricity imports and demand charge reductions, and ancillary services may offer potential additional revenue streams. C H A P T E R 9 Conclusions
Conclusions 47 The most important factors in calculating microgrid returns have been shown to be natural gas price, carbon cost, DER costs, and utility tariff costs. Many funding mechanisms and ownership models are available, and new strategies and opportunities are emerging. State and federal incentives and subsidies continue to play a major role in project feasibility, particularly in ensuring that microgrids provide more clean power to the distribution grid and limit the uptake of small-scale natural gas generators that undermine climate policy goals. A review of existing microgrids and recently conducted feasibility studies concludes that microgrids can be a viable tool for many buildings and facilities, including airports and public transit operations. A key piece of determining viability, however, is attributing a value to resil- ience and outage avoidance. This value can be difficult to quantify. For microgrids to become common at airport and public transit entities, further research is suggested. This research includes focus on the impacts of power interruptions. Regarding the occurrence frequency or duration of power disruptions that affect operations, the conse- quences to airport and public transit entities are not well understood. Increased monitoring would help form a better picture of the true costs of disruptions to owners, tenants, vendors, and travelers. Other next steps could include dissemination of success stories as some of the currently planned projects are completed, and the production of a prescriptive guide to outline the planning, design, and implementation processes. As a whole, the microgrid industry would benefit from transparent interconnection processes, central databases of state-by-state regula- tory information and ancillary service opportunities, and increased communication between utilities, airport/public transit operators, and regulators.