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Microgrid Effects and Opportunities for Utilities Staying Reliable for Your Customers

By Dave Barr, PE, PMP; Chrissy Carr, PE; and Eric Putnam, PE, CEM

Many large utility customers, including Background military installations, campuses and While the use of distributed generation, backup universities, are considering microgrids to power for critical loads, and the ability to self- better manage energy usage and enhance generate power in an island disconnected from power quality and system reliability. In addition the grid is not new, the term “microgrid” is gaining to greater energy security, microgrids offer popularity and is a focus of government and a variety of economic benefits ranging from commercial power users. While microgrids can greater efficiency of operation to the ability to take many forms, the U.S. Department of Energy facilitate participation in demand response (DOE) defines a microgrid as the integration and and interruptible rate programs provided by control of multiple local generation and storage the local utility. There are many scenarios and assets (diesel generators, combustion turbines, environments where a utility can benefit from a PV arrays, battery systems, etc.) to provide on-site customer’s implementation of a microgrid. generation for local loads in both grid-tied and islanded modes of operation.

Image 1: Shands Cancer Hospital Campus, University of Florida.

TECHBriefs 2013 No. 4 4 Burns & McDonnell Drivers for Microgrids parallel operation of the distributed resources. By allowing multiple generation assets to By operating in parallel, the customer can remove provide power for a common load, microgrids not only its entire load from the utility grid, greatly increase both the reliability of power and but it can also provide the full capacity of the efficiency of generation. Typically, the greatest distributed generation assets to the utility. Thus, a beneficiaries of microgrids are customers with customer with 2MW of generation serving a peak large, mission-critical facilities or large power load of 1.3MW can actually reduce the utility’s consumers in areas prone to frequent and/ load by 2MW. This benefit is further enhanced or prolonged outages (e.g., hurricane zones). if the customer also has renewable resources Although facilities like these have used on- available. In addition, operating in parallel allows site generation in the past, they are starting the customer to simultaneously participate to migrate toward microgrids because of the in other ancillary services such as providing many examples of single generators failing voltage and reactive power to the utility. This during prolonged outages and leaving the entire does, however, require the utility to approach mission in jeopardy. In addition, customers microgrids in a more progressive way than in areas experiencing greater stress on the they have typically done in the past and allow transmission and distribution system (e.g., customers to export power in these situations. Northeast ) are beginning to If this is done, the combination of utility reconsider the scale of their on-site power needs incentives along with the greater energy security and installing microgrids to alleviate concerns of is often sufficient grounds for an end user to events like the Northeast Blackout of 2003. install the necessary equipment for a microgrid.

The U.S. Department of Defense (DOD) Microgrid for Shands Cancer Hospital identified reliability on the commercial electrical As an example, Burns & McDonnell designed grid as a significant vulnerability to its mission, and constructed a microgrid for the campus particularly in light of growing threats of serving the Shands Cancer Hospital at the cyberattacks on critical (refer to University of Florida (see Image 1). This project the Defense Science Board Task Force on DOD was a partnership between the hospital and Energy Strategy report, “More Fight – Less Fuel,” Gainesville Regional Utilities (GRU), the local February 2008). This concern was reiterated utility company. GRU built, operates and in an October 2012 speech by Leon Panetta, maintains an on-campus energy center that then secretary of defense. Cyberthreats such provides all utilities (i.e., chilled water, steam, as Aurora and Stuxnet are real-life examples of normal and emergency power, and medical threats to power control and utility systems. gases) to the campus. To provide these utilities reliably and efficiently, the energy center uses Benefits for End-Use Customers a microgrid that can supply the entire campus’ Obviously, customers with a microgrid designed power demands and includes both a combustion to completely carry their normal day-to-day turbine generator and a diesel generator. For loads can easily participate in a demand maximum efficiency, the turbine generator response program by switching to an island is part of a combined heat and power (CHP) mode of operation when market conditions are solution that captures waste heat to generate favorable. Although not explicitly a requirement the steam required by the hospital. Since of microgrids, it is not uncommon for those with the thermal load can result in an operating this capability to be provided with the ability to condition where the turbine is producing more seamlessly transition to and from the local utility. electricity than is needed by the campus, GRU This actually provides both the customer and the routinely exports power from this system to its utility with a much more desirable alternative — grid for consumption by other customers. In a

Burns & McDonnell 5 TECHBriefs 2013 No. 4 1.4

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0.8 300 Fuel savings due to generator optimization Power (kW)Power 0.6 200 Fuel consumption (gal/m) consumption Fuel

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PV output Total microgrid load Traditional fuel consumption SPIDERS fuel consumption

Figure 1: Typical microgrid power and fuel consumption.

traditional utility agreement, the hospital would This greatly reduces the likelihood of a power have needed to instead use packaged boilers outage during the storm since all of the campus for the excess steam load to prevent exporting distribution is underground and there are no power, which would have reduced the overall outside influences on the system (e.g., a lightning efficiency of the system. strike on an adjacent feeder). Once the storm has passed and the system is stable, it is seamlessly Although a CHP can be implemented without reconnected to the utility grid. Any outages in a microgrid, Shands officials recognized that the regionwide utility system are, thus, fully the community expects to be fully mitigated for the hospital. operational at all times. This perception is even more critical for Shands, which has a One other benefit of this particular microgrid is Level 1 . With this in mind, the the ability to load test the emergency generator campus was built as a fully rated microgrid so without either interruption of power to the the turbine generator could supply all of the users or use of a load bank. Typically, hospitals power to the campus even with the loss of both perform their generator load tests by connecting redundant utility feeds. Since a CHP already resistive load banks to the generators, turning required operation in parallel with the utility, the generator’s output directly into heat without a seamless transition to/from island operation doing any useful work. At the Shands Energy Dave Barr, PE, PMP, is the was an obvious feature to include with this Center, the emergency generator is allowed to director of federal projects for system. Thus, when a significant storm or run parallel to the utility grid so it can be fully Burns & McDonnell. He has more hurricane is headed toward the hospital, GRU loaded by doing useful work. It’s a better test than 20 years of experience in the design and design-build of islands the campus without affecting the end of the generator and is more financially and mission critical facilities and customers in any way. environmentally efficient. infrastructure.

TECHBriefs 2013 No. 4 6 Burns & McDonnell Protection for the Power Grid are decoupled from their individual loads, The DOD is considering microgrids as part of a allowing a single generator to serve multiple mitigation strategy to protect critical missions loads and allowing the PV to support the loads. from vulnerabilities to cyberattacks or other Under operation of the SPIDERS microgrid, adversarial attacks on the nation’s power grid. A critical loads were served continuously during a great deal of the logistics for U.S. troops in other three-day simulated , and testing countries is based within the continental United indicated the system served the loads using 30% States. Thus, electrical power within the bases less diesel fuel by operating fewer generators on U.S. soil is a critical resource for the military’s at more efficient points and by integrating war-fighting capability. renewables into the power island (see Figure 1).

The DOD and DOE have developed a three- Benefits for Utilities phase demonstration known as Communities have come to rely upon electric Smart Power Infrastructure Demonstration utilities to support critical functions such as for Energy Reliability and Security (SPIDERS). military installations and hospitals. Severe Under the SPIDERS program, the DOD is weather events highlight the potentially demonstrating and testing the effectiveness of devastating impacts of prolonged power outages. using multiple diesel generators in conjunction Recently, during Hurricane Sandy, a major New with photovoltaic (PV) arrays and other energy York hospital had to evacuate 300 storage media to operate a stable, medium- after both the utility's power supply and backup voltage microgrid upon prolonged loss of utility generators failed. Utilities often bear the brunt Chrissy Carr, PE, is power. The goals of the program are to increase of negative public perception and increased an electrical engineer reliability of backup power systems as well as regulatory pressure after such incidents, whether specializing in the design of reduce fuel consumption. One key feature of this justified or not. Both utilities and their customers systems and supporting critical operations benefit from the utility automation. She has 23 program is that it uses existing assets whenever years of and project possible. Thus, it is not a “clean sheet” approach increased reliability that microgrids provide, management experience. to creating microgrids, but one that mimics particularly in times of disaster. what the DOD and private could do as a lowest-cost approach. As existing distribution systems are stressed by aging infrastructure and demand growth and as Phase I of SPIDERS supports mission-critical a utility’s ability to execute capital projects for loads at Joint Base Pearl Harbor Hickam new generation, transmission and distribution (JBPHH) in Hawaii. Military facilities in are hampered by regulatory and environmental Hawaii have experienced multiday losses of roadblocks, the additional flexibility in system utility power due to tropical storms, and do operations provided by on-site generation not have the luxury of importing power from and microgrids become more attractive (see nearby states. Burns & McDonnell designed, Figure 1). In addition to reducing demand on the constructed and tested the SPIDERS Phase I , microgrids can also help utility microgrid and documented significant operation through the addition of reactive power enhancements in reliability and security. Prior to generation and other frequency and voltage SPIDERS, critical loads were individually served regulation improvements to load balancing Eric Putnam, PE, CEM, is an by isolated generators that were oversized for and power quality. As distribution electrical engineer specializing in the normal load, and thus ran inefficiently. automation continues to evolve for the utilities, the design of aviation and high- Also, renewable energy assets such as PV arrays new will be available to better tech facilities. He has 20 years were of no value upon loss of utility power. monitor and control the distribution grid to use of industry experience, including these benefits. work with Phase I and Phase II When connected to the microgrid, generators projects for the SPIDERS program.

For more information, please email [email protected], [email protected] or [email protected].

Burns & McDonnell 7 TECHBriefs 2013 No. 4 TECHBriefs

• Diversity Matters — Space Diversity, That Is • Microgrid Effects and Opportunities for Utilities

Conclusion Utilities should consider development and There are many scenarios and regions of the operation of microgrids for large utility country in which both utilities and customers customers as part of their growth strategies. can benefit from properly implemented and Increasing incidents of serious storms causing operated microgrids through improved power long-term power outages in densely populated reliability and more efficient energy generation areas and new threats such as cyberattacks are and consumption. As implementation of smart highlighting vulnerabilities to critical missions. grid technologies increases in utility distribution The growing availability of financial incentives, networks, there will be even more potential for including demand-response and grid services, utilities and customers to optimize distributed make on-site power generation more viable. energy resources.