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Siemens outlines design for mini-grids to power Puerto Rico

By on July 25, 2018

SAN JUAN – Siemens Corp., a global electrification, automation and digitalization conglomerate that is devising the Puerto Rico Electric Power Authority’s (Prepa) blueprint for the future, released a white paper on Monday, titled “Resilient by Design: Enhanced Reliability and Resiliency for Puerto Rico’s Electric Grid.

Introducing its recommendations for a new energy infrastructure framework for the island, the energy giant said that since its last integrated resource plan (IRP) in 2015, Puerto Rico’s electric power system “has experienced significant upheaval” after having been severely struck by hurricanes Irma and Maria – “combined with the steep drop in the cost of renewables and battery-based energy storage.”

The developments, Siemens said, “offer Puerto Rico a rare and powerful opportunity to redesign its power system, producing a significantly more resilient grid by design that will ensure a steady flow of cleaner and higher quality power for its residents and businesses. ”

The company-commissioned white paper outlines an approach to a distributed energy system (DES): 10 mini-grids throughout the island that would incorporate and enhance existing energy infrastructure. “The mini-grid solution incorporates energy storage, renewables, and existing conventional infrastructure that will operate both connected to the grid as well as in island-mode in case of natural disasters,” as explained in a release.

Mini-grids differ from microgrids in that they incorporate “existing distribution infrastructure, and can be sized much larger than typical microgrids, for example, encompassing the San Juan region,” the paper’s authors explain.

Possible mini-grid coverage (Screen capture of

“The proposed mini-grids leverage existing infrastructure and act as ‘islands’-within-the-island – to improve resilience during natural disasters – or can be interconnected to sustain the full Puerto Rico island community during normal operations. One mini-grid could encompass the entire San Juan region, for example,” Alan Bloodgood, senior vice president of Energy and Infrastructure of Siemens Government Technologies Inc., said in the release. “This approach is tailored to meet Puerto Rico’s specific needs and would optimize a wide array of resilient energy infrastructure options by lessening reliance on one central power source, and, shorten the duration of any outages and minimize emergency power restoration costs brought about by natural disasters.”

Siemens commissioned the report to “inform the next IRP that will guide the grid rebuilding and development for Puerto Rico,” the paper reads. “By analyzing often-competing objectives such as cost, reliability and resiliency, we begin our analysis with a ‘base case’ conceptual plan focused on cost and reliability, representing a traditional centralized energy system – similar to what Puerto Rico had before Irma and Maria, with conventional power generation sited in the south and north of the island.

“Next, we identify the additional requirements needed for a resilient ‘enhanced case’ system – clearly necessitated by the recent storms and their catastrophic impacts – and determine how supply would have to be modified and redesigned or moved to add greater resiliency. To achieve the vision of a more renewable, resilient and reliable Puerto Rico electric system, our recommended plan incorporates a series of mini-grids, a different design for energy management that systematically improves resiliency by separating the existing grid into pockets of critical loads served by distributed resources that can operate in both grid-connected and island modes.”

Specifically, among those proposed, “the base case strategy achieves 20% Renewable Portfolio Standards (RPS) including large and small combined cycle gas turbines (CCGT), solar photovoltaic (PV) and battery-based energy storage. By comparison, the resilient enhanced case strategy enables the grid to reach 35% renewable penetration for a lower-emission mix of generation resources with more energy storage, distributed solar and small CCGT units, strategically located to form each mini-grid,” the paper’s summary reads.

As detailed in the report, the “resilient enhanced case strategy” prepares for “high impact events” through “reduced dependence on centralized thermal resources, use of distributed renewable generation and ability to store energy shifting daytime production to the night peaks.”

The enhanced case “results in a slightly higher levelized cost of energy (LCOE) – 7% higher over the base strategy – which is a modest increase when considering the devastating impacts to the economy if just one of the events that the system is designed to absorb were to happen again. After these recovery costs are considered, the resilient enhanced case strategy is expected to be the least cost option.”

Access the white paper here: “Resilient by Design: Enhanced Reliability and Resiliency for Puerto Rico’s Electric Grid.

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