Pacific Gas & Electric (PG&E) has rolled out a new plan to keep power flowing during the 2020 wildfire season, which includes forming a microgrid from an existing natural gas-fired plant.
The California utility outlined its strategy in an April 1 filing before the California Public Utilities Commission (Rulemaking: 19-09-009).
The new plan replaces a program to install permanent microgrids this year at 20 substations. The utility recently announced that it was temporarily suspending the 20 microgrids after it became clear it would be difficult to build them by September, the traditional beginning of wildfire season.
The purpose of the microgrids — and the new plan — is to keep the power flowing to customers if the utility is again forced to enact public safety power shutoffs — the de-energizing of lines to prevent them from sparking wildfires. The shutoffs last Fall caused power outages in northern California that crippled business and day-to-day activities.
The utility is now negotiating with the owner of the 44-MW Red Bluff power plant to make the plant capable of acting as a microgrid — going into island mode — when it is necessary to de-energize lines that serve two substations, Rawson and Tyler.
The simple cycle natural gas-fired plant is owned by Purenergy, a subsidiary of NAES.
If the negotiations and installation are successful, the customers served by the two substations would continue to receive electric service via the microgrid during a shutoff.
Temporary microgrid fleet exceeds 300 MW
In addition to microgridding Red Bluff, PG&E has struck agreements to rent mobile generation and associated services for use at temporary microgrids to energize substations during the 2020 fire season.
The utility did not specify the capacity of the mobile generation, but said it is greater than the 300 MW it originally planned to use. In response to environmental concerns, PG&E said it is focusing on using renewable diesel for temporary generation.
PG&E offers cost comparisons
The utility also offered updates on its evaluation of the 20 substations identified for permanent microgrids. Upon further examination, the utility found that local generation makes sense for 13 of the sites, while the others may benefit more from adding generation and transmission capacity and voltage support, according to the filing.
In the evaluation, the utility identified high level costs for the various solutions, including:
- Transmission line switching, $1 million per switch
- Transmission line building, $2.5-$4 million/mile
- Undergrounding transmissions lines, $20-$35 million/mile
- Microgrids with permanent generation, $1.5 million/MW, plus $7.5 million in required substation upgrades.
The cost proposed for each microgrid, which the utility secured via competitive bids, is redacted.
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