SDG&E Shares Future Plans for Borrego Springs Microgrid
Last updated 3/4/2022 at 9:32am
At its February meeting, the Sponsor Group hosted representatives from SDG&E who provided a comprehensive update of future plans to make the Borrego Springs Microgrid sustainable and resilient, and answer residents' questions. Earlier, SDG&E had attended the January meeting of the Infrastructure Subcommittee of the Borrego Springs Revitalization Committee, but many residents' questions and concerns had remained unanswered.
First, some background about the microgrid. As a remote community, Borrego Springs is served by a single electrical transmission line that connects to the Narrows substation on Route 78 and from there to the Warner Springs substation at the intersection of Routes 79 and S-2. Over the last decade, SDG&E has developed the Borrego Springs Microgrid to achieve resilience to outages on the transmission line. During normal operation, the microgrid is connected to the larger state-wide grid and energy can flow between the state-wide grid and the microgrid depending on local demand and local supply. During outages, the microgrid can operate in "island mode" disconnected from the larger state-wide grid, i.e., fed only from available local energy generation and storage.
The Borrego Springs Microgrid is a first-of-its-kind demonstration project in the U.S. In 2020, SDG&E received a $4.5 million federal grant from the U.S. Department of Energy's Solar Energy Technologies Office (SETO) to transition the Borrego Springs Microgrid to 100% clean energy. Lessons learned from this transition as well as general microgrid operations will be shared with utilities nationwide.
The microgrid is operated in island mode during planned outages for grid maintenance and testing. During a daytime outage, energy from rooftop Solar and two local commercial Solar plants is supplemented with SDG&E's local microgrid battery storage and diesel generators. For a nighttime outage, the current storage capacity and generators in the microgrid are sufficient to power essential community services; non-critical loads may be shed, as necessary. In December 2019, the microgrid provided power to all of Borrego Springs during planned compliance maintenance testing and repairs for 10 hours.
When an unplanned outage occurs, the microgrid island mode is not automatically initiated. For safety reasons, the process is initiated only after SDG&E is able to patrol the region to identify and isolate any cause of the unplanned power outage. Since staff must be dispatched from San Diego to conduct these inspections and initiate the failover, the process is expected to take four hours. This has been the source of frustration for residents. Clint Brandin, President of the Borrego Springs Chamber of Commerce, reminded SDG&E staff that the October 2021 event resulted in thousands of dollars of losses at local businesses. Laurence Abcede, SDG&E Distributed Energy Resources Manager, described the challenges that the Borrego Springs Microgrid presents due to the variability of Solar production, and the variability of demand from residential and commercial customers, including water pumpers in the region. An unexpected spike in demand resulted in the extended October outage. Laurence promised that SDG&E will continue to collaborate with the community to schedule planned maintenance and testing events to minimize the hardship to residents and businesses.
SDG&E staff presented two major projects slated for the Borrego Springs Microgrid. Melanie Davidson and Pooyan Kabir presented information about the Borrego Springs Microgrid Green Hydrogen Project. Kelly Fitzgerald and Todd Voorhees presented the Tie Line 686 Wood to Steel Replacement Project.
Borrego Springs Microgrid Green Hydrogen Project. Renewable energy sources – Solar and wind – have periods of energy surplus and periods of energy deficit. As California embarks on a fully renewable-energy future, there is a need for thousands of MWh of energy storage. Compared to batteries and pumped storage, hydrogen offers a clean, cost-effective, long duration, and scalable energy storage solution. This year SDG&E is piloting a long duration hydrogen energy storage solution (reducing the use of diesel-powered generation) at the Borrego Springs Microgrid. The process works as follows. Using local renewable energy from Solar, hydrogen is extracted from water and stored as hydrogen gas in storage tanks on site. A hydrogen fuel cell converts the stored hydrogen to supply electricity to the grid as needed, such as when there is a renewable production deficit.
For the Borrego Springs pilot, the electrolyzer consumes 1 MW to produce 18 kg of hydrogen per hour, while consuming 60 gallons of water per hour. (As a rule of thumb, 1 kg of hydrogen has energy equivalent to one gallon of gasoline.) Hydrogen is stored in 2 tanks, each with a 188 kg capacity. During production of electricity, the fuel cell consumes 17 kg of hydrogen per hour to produce 250 kW of electricity. From the above figures, I noticed the low "round-trip efficiency" of hydrogen as an energy storage solution – consuming 1 MWh of power to store 18 kg of hydrogen, then using 17 kg of hydrogen to produce 250 kWh of electricity. The following document from the National Renewable Energy Laboratory (NREL) https://www.nrel.gov/docs/fy19osti/73520.pdf provides a comparison between battery and hydrogen storage. Compared to batteries, the storage cost of hydrogen is low and scales well, but it comes at a higher cost of charging and discharging equipment, and low round-trip efficiency. Where surplus renewable energy is going unused anyway, hydrogen storage can offer an inexpensive storage solution.
SDG&E staff responded to questions about safety, water use, and wastewater disposal. Hydrogen is produced and consumed on site and will not be transferred in and out of Borrego Springs. Hydrogen production is a mature technology, and over ten million metric tons of hydrogen is produced in the US each year. The Borrego Springs project follows all national safety standards and regulations. As mentioned above, when hydrogen fuel is being produced, the process consumes 60 gallons of water per hour. Wastewater will not be fed into the aquifer but sent to a lined evaporation pond on site.
As the project is in the planning stage, not all information presented here is final. Please look for more information and answers to questions about the Borrego Springs hydrogen storage project in coming months.
Tie Line 686 Wood to Steel Replacement Project. As shown in the first map (below), Tie Line 686 (yellow) connects the Warner Springs substation to the Narrows substation. Tie Line 687 (blue) connects from the Narrows substation to Borrego Springs. Tie Line 686 was originally constructed in 1924.
The wood to steel replacement project (see top right graphic) is targeted at high fire threat districts (HFTD), the first 14.8 miles from Warner Springs substation. The project start and end are indicated on the second map. In the 14.8-mile segment, 209 wooden poles will be removed and replaced with a total of 140 new steel poles. The project crosses Vista Irrigation District land, BLM land, ABDSP land, the Pacific Crest Trail, as well as private property. Micropile foundations will be used to minimize the amount of ground disturbance, especially in areas with culturally sensitive resources. Poles with micropile foundations can be constructed via helicopter to minimize access and travel restrictions. In the Q&A, SDG&E staff indicated that permitting is expected to take 18 – 24 months, and construction is expected to start in 2025.
If you have questions for SDG&E about the Borrego Springs Microgrid, including the two new projects, please contact Elizabeth Rodriguez (email: firstname.lastname@example.org). Also, Dallin Young, SDG&E Public Affairs Manager may be reached at email@example.com. Elizabeth is the liaison to SDG&E from the Infrastructure Subcommittee of the Borrego Springs Revitalization Committee. She is working with SDG&E to schedule a follow-up with SDG&E at an upcoming meeting of the Infrastructure Subcommittee.
Update on the La Casa del Zorro Solar Project. John Wells of La Casa del Zorro provided a brief update on the Solar project. They have received project approval with the smaller footprint. They have now started looking at fencing options. They will post progress updates and photos online at lacasadelzorro.com/solar, and welcome community input and engagement. They will be back with an update to discuss fencing options at the March Sponsor Group Meeting.
The next regular meeting of the Borrego Springs Community Sponsor Group is scheduled for March 3, 5 p.m. Sponsor Group member voted to continue to meet via video conference for the March meeting. For further information and to be added to the Sponsor Group email list to receive agendas, agenda packets, and a Zoom link, contact the Chair at firstname.lastname@example.org.
A Special Meeting of the Sponsor Group will be held via Zoom on February 16, 5 p.m. The agenda is limited to 1. Decorum, Practices and Procedures at Sponsor Group meetings; 2. Discussion about the Sponsor Group mission; and 3. Discussion of roles and responsibilities of Sponsor Group members.