Cascadia Ridge BESS — Community Research

Jupiter Power LLC wants to build a 130 MW lithium-ion battery storage facility on about 45 acres in unincorporated King County, on Snoqualmie Ridge. It would connect to PSE’s Mt. Si substation via a 115kV tie-line.

View larger map — Marker shows approximate center of the proposed site.

We’re not against this project. PSE needs grid storage for CETA compliance, and the Mt. Si substation next door makes this a logical site. Storage here would strengthen grid reliability for the Eastside, including Snoqualmie Ridge. We want that.

But lithium-ion is the wrong battery for this location. The fire, noise, and environmental risks are real — and they’re solvable with technology Jupiter Power has already committed to for its other projects.

What we’re asking for

  1. Sodium-ion or equivalent non-lithium-ion chemistry. Jupiter Power signed a $500 million sodium-ion deal with Peak Energy last year. Their CTO called it a “potential game changer.” Sodium-ion doesn’t have thermal runaway, doesn’t produce hydrogen fluoride gas, and uses passive cooling instead of fans running around the clock. The facility won’t be online until late 2028 — sodium-ion will be on the market well before then.

  2. Keep the trees on the west side of the site. Critical area buffers protect the north and east edges, but the west side — facing the backyards of homes on Bracken Place SE and SE Center Street — has no buffer protection. Leaving the existing trees alone costs the project nothing.

Why this matters

EPRI tracks two failure metrics. Their per-project rate (0.3%/yr) puts the 15-year compound probability at 1 in 23 (4.4%). Their per-GW rate (0.3 failures/GW/yr), which accounts for facility size, puts a 130 MW facility like Cascadia Ridge at 3.9% per year — compounding to 45% over 15 years. The truth is somewhere in between, but neither number is small. Here’s the full analysis.

This site is adjacent to thousands of homes on Snoqualmie Ridge, next to Fisher Creek (salmon habitat), in a ridge-bounded valley where temperature inversions can hold smoke close to the ground.

Where things stand

No active permit application as of March 2026. Jupiter Power filed a Commercial Site Development permit in December 2025 and canceled it in February 2026. King County’s BESS ordinance requires a community meeting before filing a permit application — Jupiter Power held an open house on March 17, which may have been needed before resubmitting.

Get involved

Want to do something about it? There are concrete steps you can take right now — from contacting your representatives to preparing for the SEPA comment period.

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Project details · Site and environment · Battery technology · CETA and grid storage · Permitting