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Prepa Wants 8 Minigrids, Various Microgrids With Storage

By on February 8, 2019

Editor’s note: The following originally appeared in the Feb. 7 -13, 2019, issue of Caribbean Business.

The Puerto Rico Electric Power Authority (Prepa) is proposing the division of the island’s transmission and distribution system into eight minigrids and a host of microgrids with energy storage. On the supply side, Prepa is proposing at least eight installations, including liquefied natural gas (LNG) projects.

The initiatives are contained in a draft of the integrated resource plan (IRP) that Prepa is scheduled to finalize and submit to the Energy Bureau Feb. 12 as required by Act 57 of 2014.

The IRP focuses on a more resilient energy system that would decentralize power production to avoid the repeat of the islandwide outages caused by hurricanes Irma and Maria. It calls for a shift from centralized generation in the south to more decentralized generation resources distributed across the island.

The IRP is centered on the concept of minigrids, which are defined as zones of resiliency into which the system can be segregated during and after a major weather event or natural disaster, ensuring the load can be served using local resources and supporting the effective and timely recovery from the event. Its implementation will transition the Puerto Rico electric system from one centered on fossil fuels to one in which renewable resources play a central, if not predominant role.

Complementary to the minigrids, smaller microgrids have been identified for those areas, due to geography and system topology, and are likely to remain isolated. Several of these projects are already being recommended for Puerto Rico.

On the supply side, Siemens, which prepared the IRP, examined various long-term capacity-expansion plans and agreed to the following:

  1. Maximize the installation rate for solar photovoltaic (PV) generation for the first four years (2019 to 2022) of the plan. The recommendation is to issue requests for proposals (RFPs) in blocks of about 250 megawatts (MWs), and depending on pricing and Prepa’s capability to interconnect, continue to add blocks with a goal of interconnecting at least 750 MWs and possibly 1,200 MWs over this period.
  2. Install between 500 MWs and 1,100 MWs of battery energy storage in the first four years of the plan. The amounts of battery storage are heavily correlated with the total number of PVs to be installed and the local energy supply required for the minigrids into which the system is expected to segregate during major events.
  3. Convert the San Juan Units 5 & 6 combined cycle (CC) to burn natural gas. This option is an ongoing initiative using a ship-based LNG terminal and was adopted as a given in the formulation of all plans where there is new gas development.
  4. Develop a land-based LNG terminal in San Juan to supply a new CC gas turbine (CCGT) and San Juan’s Units 5 & 6 CC.
  5. Install a CC gas turbine at Costa Sur Steam Plant or extend a renegotiated contract with EcoEléctrica. Under all cases, unless the contract with EcoEléctrica is renegotiated to significantly reduce the fixed payments and the plant is allowed to cycle frequently, EcoEléctrica is replaced by a 300 MW CCGT after the contract expires in 2022.
  6. Install new GTs capable of burning containerized natural gas. The need to serve critical and priority loads within the minigrids for resiliency resulted in the necessity to add 17 to 18 small GTs of 23 MWs each at selected locations in the grid; specifically, Caguas (Yabucoa), 5 units; Carolina (Daguao), 5 units; Cayey, 2 units; Ponce East (Jobos), 2 units; and Mayagüez North (Aguadilla), 2 units, among others.
  7. Develop a ship-based LNG terminal in Mayagüez.
  8. Develop a ship-based LNG terminal in Yabucoa.

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