By Efraín O’Neill-Carrillo, Isaac Jordán, Agustín Irizarry-Rivera, and Rafael Cintrón The Long Road to Community Microgrids Adapting to the necessary ICROGRIDS OFFER TREMENDOUS OPPOR- tunities in isolated areas or developing changes for renewable countries that are unable to establish a tra- energy implementation. M ditional power infrastructure. However, microgrids face vast challenges in places where the dominant model is based on a centralized, hier- archical infrastructure with policies and institutions developed to support such infrastructure. Renewable ener- Digital Object Identifier 10.1109/MELE.2018.2871239 Date of publication: 16 November 2018 gy researchers at the University of Puerto Rico–Mayaguez 6 IEEE Electrification Magazine / DECEMBER 2018 2325-5987/18©2018IEEE (UPRM) have traveled a long road advocating 2010. In 2008, researchers at UPRM quantified the poten- distributed energy resources (DERs) and com- tial for electricity generated from local renewable energy munity microgrids. sources. They found that the best renewable resource with commercially available technology in Puerto Rico is Overview of Electric the sun (Figure 2). Figure 3 shows the potential for gener- Energy in Puerto Rico ating solar electricity using photovoltaic (PV) panels on In 1941, the Puerto Rico Water Resources residential rooftops. All of the electric energy in Puerto Authority (AFF, its acronym in Spanish) was Rico could come from using PV systems in 65% of resi- created as a public power company to plan, dential rooftops once we obtain an efficient, cost-effec- design, construct, operate, and maintain tive, and environmentally sound technology to store Puerto Rico’s electric infrastructure. As part of electric energy for use at night. Figure 4 shows results a plan to take many Puerto Ricans out of the from another UPRM study [funded by the U.S. Depart- dire conditions they lived in the 1930s, Anto- ment of Energy (DOE)] proving that residential rooftop PV nio Lucchetti proposed to integrate all of the systems already had an average cost of between 11 and electric power systems in Puerto Rico. War- 12 cents per kWh in 2013 (assuming an installed cost of time circumstances enabled the final acquisi- US$3 per watt, net metering, and four hours of “peak tion of private power companies, which sun”). In contrast to most U.S. jurisdictions, rooftop PV helped the AFF complete its mission: the systems with net metering have been economically fea- electrification of Puerto Rico. sible in Puerto Rico since at least 2010, reaching grid pari- The AFF accomplished its founding mis- ty near that time. sion in the 1970s. While its name changed to A key challenge is to turn the potential for renewable the Puerto Rico Electric Power Authority energy into a reality through a safe and reliable grid con- (PREPA) in 1979, its mission stayed the same. nection. The differing opinions regarding this matter result As of December 2018, PREPA is a vertically from the fact that traditional power systems were built and integrated utility and is one of the largest operated based on the assumptions of that time. Conse- public power companies in the United States, quently many electric companies around the world (includ- and remains the only provider of retail elec- ing PREPA) have usually reacted negatively to renewable tricity on the island (Figure 1). It has more energy, believing that it complicates conventional power than 2,400 mi of transmission lines (230 and system operation. Despite these challenges, distributed MOUNTAIN: ©ISTOCKPHOTO.COM/ALEJANDROPHOTOGRAPHY, MOUNTAIN: INGRAM PUBLISHING LICENSED BY SOLAR PANELs—imaGE 115 kV), 51 115-kV transmission centers, 283 generation continues to grow in Puerto Rico, furthered by subtransmission substations (38 kV), and the passing of Act 133 in 2016, which permits solar commu- over 30,000 mi of distribution lines (13.2, 8.32, nities and microgrids on the island. 7.2, and 4.16 kV). New technologies, practices, and oppor- PREPA’s mission was finally updated in 2014 to reflect a tunities were missed because of the lack of a renewed new mandate toward a sustainable energy future. A new mission to face the challenges of the latter quarter of the regulator, the Puerto Rico Energy Commission, was created 20th century and begin an ordered and comprehensive transforma- tion of the electric infrastructure, its business structure, and custom- 728 MW er service. On the other hand, 248 MW Dos Bocas 840 MW Caonillas Cambalache Palo Seco there was no holistic planning or San Juan integration of energy strategies and technologies in Puerto Rico, Rio Blanco 220 MW and changes in energy policy direc- Mayaguez tions (due to excessive partisan inter- ventions in PREPA) were an obstacle Garzas I and II for decades. Toro Negro I and II An area of disagreement in the Yauco I and II last 20 years between PREPA’s AES Costa Sur ecoEléctrica Aguirre management and electricity users 507 MW 454 MW 1,032 MW 1,534 MW has been the use of renewable Oil (6, 2, or Diesel) Not Shown: 386 MW from Smaller Units Distributed sources to produce electricity. In Hydro (100 MW) spite of PREPA’s narrow planning Coal Around the Island Installed Capacity: 5,839 MW (3,443 MW in the South) vision, a net-metering law was Natural Gas enacted in 2007, and a renewable portfolio standard became law in Figure 1. The installed generating capacity in Puerto Rico. (Image courtesy of Dr. Agustín Irizarry.) IEEE Electrification Magazine / DECEMBER 2018 7 Barceloneta Vega Baja Toa Baja Quebradillas Hatillo Carolina Manati Vega Alta Cataño Canovanas Dorado Aguadilla Rincón San Loiza Isabela Arecibo Moca Camuy Juan Aguada San Florida Toa Alta Trujillo Río Luquillo Morovis Sebastián Corozal Alto Grande Fajardo Bayamón Añasco Ciales Guaynabo Lares Utuado Naranjito Aguas Gurabo Ceiba Las Marías Orocovis Buenas Juncos Naguabo Mayagüez Comerio Jayuya Barranquitas Caguas Hormigueros Maricao Adjuntas Cidra San Villalba Aibonito Humacao San Lorenzo Coamo Cayey Germán Yauco Ponce Yabucoa Cabo Juana Las Rojo Lajas Díaz Santa Salinas Piedras Guánica Isabel Guayama Maunabo Sabana Guayanilla Peñuelas Patillas Grande Arroyo 1,495 → 3.4 h 1,952 → 4.5 h 2,408 → 5.5 h 1,343 → 3.1 h 1,800 → 4.1 h 2,256 → 5.2 h 1,191 → 2.7 h 1,648 → 3.8 h 2,104 → 4.8 h Figure 2. The annual average insolation in kWh/m2 and peak sun hours. in 2014. Also in that year, PREPA began a restructuring pro- 40 cess to address the financial problems that had been 35 evident since the early 2000s. The existing electric infra- 30 structure was built for an industrial economy, but the loss 25 of 1,000 industrial clients left Puerto Rico with a generation 20 overcapacity. The decade between 2007 and 2017 saw a 15 48% reduction in industrial demand (after its 2006 peak), a 10 13% loss in the residential sector (after its 2005 peak), and a Annual GWh Generated 5 10% loss in commercial demand (after its 2007 peak). In 0 2017, PREPA filed for bankruptcy protection under Title III 0102030405060708090 100 of the Puerto Rico Oversight, Management, and Economic Available Rooftop Area (%) Stability Act, a U.S. law. One option for overcoming PREPA’s Figure 3. The potential for electricity production from residential roof- difficult circumstances is to facilitate the use of DERs, top PV systems. which present an opportunity for local socioeconomic development—if priority is given to renewable energy in a hybrid sys- tem that enables solar communities Levelized Cost of Energy (LCOE), US$/kWh and microgrids. (Net Metering, 20 Years, 1% Annual Degradation) US$0.25 0.22 0.19 Renewable-Driven Microgrids US$0.20 EI Yunque 0.18 0.16 In Puerto Rico, approximately 70% of US$0.15 0.15 0.13 0.17 0.13 0.12 0.11 the population lives in areas with an 0.15 0.13 US$0.10 excellent solar resource (Figure 2). 0.12 0.11 US$/kWh 0.10 0.09 Adjuntas, Canóvanas, 0.09 0.08 Hence, rooftop PV systems in Puerto US$0.05 Cabo Rojo Sur Mayaguez Norte Guánica Rico have greater potential when US$0.00 compared to other renewable re­­ 2.5 3 3.5 4 4.5 5 5.5 sources. PV systems have some Peak Sun Hours drawbacks, however, such as the LCOE 4 US$/W LCOE 3 US$/W fluctuation of output power, which depends on weather conditions. One Figure 4. The cost per kilowatthour of residential rooftop PV systems. way to increase the penetration of 8 IEEE Electrification Magazine / DECEMBER 2018 PV generation is to add energy storage One option for per group (12.8 kWh per house). Loads devices. With storage and a dedicated were simulated with one of three control system, PV generators can be overcoming PREPA’s demand profiles: 100 houses used transitioned to serve the role of an 834 kWh per day, 50 houses used active generator and provide more difficult circum - 918 kWh per day, and 50 houses used flexibility for system operators and stances is to 627 kWh per day. Each grouping of users. This approach is limited by the houses had a different combination of economic and environmental issues facilitate the use profiles and was not uniformly dis- related to existing storage technolo- tributed. Load reductions represented gies. Another way to increase the use of DERs, which present DR actions. When load reduction was of rooftop PV systems is by managing an opportunity for triggered, the 834- and 918-kWh pro- the demand through demand-response files were reduced by 33%, while the (DR) strategies, which can be used to local socioeconomic 627-kWh profile was reduced by 25%. match load profiles to available renew- Demanding a constant block of able energy production.