Puerto Rico’s Grid Needs Resiliency. Here’s Why It Won’t Be Easy.

Puerto Rico's energy infrastructure must be redesigned and rebuilt with an emphasis on resilience-and that will require wide-ranging, long-term efforts, the Department of Energy (DOE) says in a new report.

In its June 20 report, "Energy Resilience Solutions for the Puerto Rico Grid," the agency lists a number of recommendations for the government of the U.S. territory to consider as it crawls toward recovery from Hurricane Maria.

The hurricane's winds, which were just below a category 5 intensity, on September 20, 2017, left nearly 100% of the island's 3.5 million citizens without power (Figure 1). The storm caused an estimated $65 billion to $115 billion in damage. While the government estimates 64 lives were lost as a result of the disaster, researchers from Harvard and other institutionssuggest roughly 4,600 people died within three months of the catastrophe, many owing to delayed medical care.

1. Blackout. Comparison of lights at night in Puerto Rico before (top) and after (bottom) Hurricane Maria. Note: Lower image date should read "September 25, 2017". Source: NOAA

While data about power loss is not included in the DOE's report, the researchers suggest that on average, households went 84 days without power, 68 days without water, and 41 days without cellular telephone coverage through December 31, 2017. In the most remote regions of the island, 83% of households were without electricity for the entire period. Power disruptions left hospitals unable to operate sophisticated pharmaceutical and medical equipment that is dependent on electricity.

Troubled Even Before the Storm

Even before the hurricane, Puerto Rico faced a number of issues that exacerbated difficulty of reliable power generation, and restoration in the storm's aftermath, the DOE's report notes. One issue was that government-owned utility Puerto Rico Electric Power Authority (PREPA) was plagued by mismanagement owing to what some officials and consultants described as an "inefficient bureaucracy."

While the island has been working to overhaul its infrastructure through energy reforms aimed to reduce political influence over PREPA's decision-making, several industry observers acknowledge that PREPA's troubles are complex. As the Puerto Rico Energy Commission (PREC) described them: "The quadrennial turnover of managers with each new political administration, the political pressures from elected officials to avoid necessary rate increases, the failure of government agencies to pay their electricity bills on time, the irresponsible initiation and termination of expensive capital projects, the high levels of electricity theft, the work rules that prevent efficient use of well-paid employees, the poor record-keeping and antiquated administrative procedure, the compensation schemes that prevent PREPA from recruiting and retaining qualified and experienced personnel-all this must come to a halt, to be replaced by a universal commitment to the good of the Commonwealth."

According to the DOE's report, PREPA acknowledged the woeful physical condition of its "ailing grid," including "degraded infrastructure" and a "deteriorated" transmission system. Between 2010 and 2015, for example, PREPA's forced outage factor of plants averaged 6.87%, "but ended that period at nearly 27%," it said. The report notes that "Some units were completely out of service for extended periods of time, while the best performing plant was fired by natural gas supplied by Gas Natural Fenosa, majority owner of EcoEli(C)ctrica, achieving an availability rate of 97% and average capacity factor of 65%."

For PREC, however, Puerto Rico's biggest hurdles stem from PREPA's dismal finances, which it said must be stabilized. "Until PREPA's financial situation improves, it cannot borrow new money. If it cannot borrow new money, it cannot repair its deteriorating physical infrastructure, prepare that infrastructure for a future of renewable energy, pay salaries sufficient to attract and keep excellent workers, and modernize its system so as to enable consumers to save money on their electric bills," it said.

Resiliency Now and Forever

Taking these considerations into account, the DOE issued a number of recommendations that Puerto Rico could take to improve its electricity system and produce an immediate effect. These include urging government entities to issue "updated, effective mutual aid agreements" to coordinate support during the next event. In the short-term, PREC and PREPA should also implement microgrid regulations, it said. These rules should be "in line with accepted industry standards and practices; and establish effective, efficient, and reasonable interconnection requirements and wheeling regulations." The rules should also allow customers to design systems "in a manner that support the reliability and resilience of the broader electricity grid," it said.

Over the longer-term, the DOE urged the government to invest in grid improvements that are based on detailed modeling. On the transmission front, that would entail conducting load flow and contingency analysis, and identifying optimal resiliency and hardening benefits for the transmission system. While the design of the island's transmission infrastructure is "fundamentally sound," the DOE also recommended an enhanced program to mitigate corrosion of the guy-wire anchor rods, improved right-of-way maintenance for access to structure locations, and updating of materials to more robust industry standard components. It also called attention to an opportunity to consider building new transmission corridors along new roads crossing mountain areas.

The location of substations, which were flooded both by saltwater in coastal areas and rainfall, should also be analyzed. If they are found within flood areas, substations should be re-sited or raised (to a 0.2% flood elevation), and waterproofed, the DOE said.

The island could also benefit from segmenting its transmission system into smaller portions to better enable system recovery and black-start restoration. Planning for segments more likely to survive a future event could include a mix of generating assets, it suggested.

A New Generation of Power Projects

The DOE noted that Puerto Rico's pre-storm average load was about 1,500 MW, with a 2,250-MW peak. But installed capacity exceeded 5,000 MW-which means that "as few as three" of PREPA's current power plants (Figure 2) could satisfy estimated load in 10 years when combined with purchased power, it said. However, though generation is adequate, siting of generation and fuel diversity will be paramount in a resilient system, it added.

2. Puerto Rico's key generation sites. Courtesy: Public Private Partnerships Authority

"Preliminary analysis shows that moving toward a more diverse fuel portfolio, including alternative fossil fuels, renewable energy and energy efficiency, will produce significant cost reductions," the report says. "Fuel-efficient load-following combustion turbines could greatly improve fuel efficiency as compared to conventional steam turbine power plants. However, as with grid infrastructure, detailed modeling, such as production cost, capacity expansion analysis and detailed machine modeling, can help determine the best course of action to integrating new generation sources for Puerto Rico."

Hardening efforts should particularly focus on plants like the 990-MW oil- and gas-fired Costa Sur power plant in Guayanilla. At plants like the oil-fired, 602-MW Palo Seco Station near San Juan-which has been retrofitted to comply with federal mercury and air toxics standards-"detailed hardening assessments should be undertaken."

Because Puerto Rico has excess generation, it can also afford to model energy interdependencies and assess fuel contingencies, including shipping concerns, source of fuels, storage locations, and the impact of disruption and emergency response. "Analysis can indicate where to prioritize dual fuel generation capability and sufficient levels of on-site fuel storage," the DOE said.

At the same time, however, the island should actively work toward reducing its dependence on imported fuels. About 90% of PREPA's generation fleet (about 4,878 MW) uses heavy fuel oil, and the remainder (961 MW) of independent power production relied on natural gas, coal, hydro, wind, and solar (Figure 3).

3. Existing generation mix and energy consumption in Puerto Rico before Hurricane Maria in September 2017. Source: DOE

Displacing oil imports with natural gas has been a key facet of Puerto Rico's energy sector reform. It already has one natural gas import terminal, which mainly supplies the 540-MW EcoEli(C)ctrica with liquefied natural gas (LNG) from Trinidad and Tobago and other markets. Before the storm, PREPA was also considering projects to convert the 1,500-MW oil-fired Aguirre and Costa Sur plants to natural gas. PREC has recommended that the Costa Sur project be repowered with a new combined cycle plant and outfitted with natural gas infrastructure.

But, according to the DOE, if Puerto Rico were to use more gas-from the U.S. to reduce foreign fuel imports-it would need gas to be shipped in compliance with the Jones Act. "There are currently no Jones Act compliance vessels available to deliver large volumes of U.S. LNG to Puerto Rico," it noted. Additionally, there may be no capacity at U.S. shipyards to build a Jones Act compliant ship for LNG transport before the mid-2020s.

A more fruitful approach would be to bank on renewable energy. In Puerto Rico-which became the first U.S. territory to require forward-looking planning in 2014, and which issued an island-wide integrated resource plan in February 2017-a law already requires 20% of sales to come from renewables by 2035, which means about 1,200 MW of renewable capacity will need to be built. On the island, the delivered cost of electricity from independent renewable power producers, from power purchase agreements signed in 2014, "compared favorably with the cost of PREPA's heavy fuel oil-fired plants," the DOE noted.

The island could explore its sizable renewable energy potential for biomass, solar, and especially ocean power (Figure 4). Biomass could replace coal at the 454-MW AES plant in Salinas, whose license is set to expire in the next 10 years. Puerto Rico could also consider power produced from municipal solid waste.

3. Puerto Rico's renewable energy potential. Source: DOE

The DOE also added that private investment in distributed generation could be encouraged if the island establishes "clear expectations regarding interconnection and remuneration," and ensures they are "adhered to consistently by all relevant parties."

Microgrids could also have a long-term function, it said. "While there is economic and reliability value in being connected to the PREPA system during normal conditions, storm recovery and community support can be enhanced through these community-based microgrids in more remote areas of the Commonwealth." More analysis may be needed, but it appears that "microgrid investment has the potential to be more cost effective than alternative system upgrades to harden the system for improved function and reliability," the DOE said.

If the island is to make any progress, however, it will also need to resolve workforce issues afflicting its power sector. Puerto Rico has lost 30% of its grid-related workforce over the past decade. Future efforts will need to focus on retention of skilled labor.

"[H]ighly skilled (or re-trained) technicians will be needed to operate future systems-e.g., control centers enabling active monitoring and control of distributed generation and microgrids; enhanced outage management functionality, integrated with an Advanced Distribution Management Systems (ADMS) and Distributed Energy Resource Management Systems (DERMS); and integrated cyber and physical asset security in all systems," it said.

-Sonal Patel is a POWER associate editor (@sonalcpatel, @POWERmagazine)

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