Strategic Undergrounding
Risk Reduction Category
Technology Description
Strategic undergrounding is a data-driven approach that identifies critical overhead distribution feeders, equipment, and lines as candidates for proactive undergrounding. A strategic undergrounding program helps identify the lines most prone to outages and considers undergrounding to improve grid resilience and the total time of restoration of overhead distribution lines [1].
A strategic undergrounding program can provide heightened wildfire resiliency and electric reliability by undergrounding electric distribution lines near key community facilities. Removing overhead power lines and placing them underground helps remove the risk of sparking fires during adverse weather. It also enables the power lines to remain energized during PSPS which reduces the impact of power outages on fire-prone communities [2].
While undergrounding can be an effective means of fire hardening the electrical system, it is likely much more expensive and may have a lower cost-to-benefit ratio relative to other methods of fire hardening [3]. In Southern California Edison’s (SCE) current Grid Safety and Resiliency Program Application (A.)18-09-002, SCE compares the costs and benefits between three different wildfire mitigation options for their overhead infrastructure located in the High Fire Threat District:
- Re-conductoring and pole replacement with conventional wires and wooden poles
- Installing or re-conductoring and pole replacement with covered (insulated) conductors and fire- resistant metal poles
- Underground conversion of overhead infrastructure
SCE calculated the data in the following table which compares these fire mitigation options:
| Mitigation Effectiveness-to-cost Ratios for Undergrounding Alternatives | ||||
|---|---|---|---|---|
| Mitigation Option | Relative Mitigation Effectiveness Factor* | Cost per Mile | Mitigation Effectiveness-to-Cost Ratio | |
| Southwire | Re-conductor 0 Conventional poles and conductors | 0.15 | $300,000 | 0.5 |
| Covered Conductors and Fire-Resistant Metal Poles | 0.6 | $480,000 | 1.4 | |
| Underground Conversion | 1 | $3,000,000 | 0.33 |
*Undergrounding serves as the baseline for measuring mitigation effectiveness
According to SCE, underground conversion is roughly 7 times more expensive than covering the conductors and replacing wooden poles with fire resistant poles. Additionally, the latter option has a mitigation benefit- to-cost ratio that is significantly higher than both undergrounding and conventional pole and wire replacement [3]
Technical Readiness (Commercial Availability)
Implementations/Deployments
Innovations as of Mid 2023
Potential Enrichment Work Opportunity
References
[1] https://www.tdworld.com/intelligent-undergrounding/article/21146693/strategic- undergrounding
[2] https://www.sdge.com/undergrounding-overhead-powerlines