FAQ

What is a BESS?

A Battery Energy Storage System (BESS) is a facility that stores electricity in large banks of batteries and releases it back to the grid when needed. The proposed Cascadia Ridge facility would be 130 MW / 520 MWh — enough to power roughly 100,000 homes for four hours. At utility scale, a BESS consists of battery modules housed in prefabricated enclosures, along with inverters, transformers, cooling systems, fire suppression equipment, and a substation connecting to the transmission grid.

Why is PSE interested in having a BESS?

Washington’s Clean Energy Transformation Act (CETA) requires utilities to be greenhouse gas neutral by 2030 and supply 100% clean electricity by 2045. Wind and solar don’t generate power on demand — they produce when conditions are right, not necessarily when people need electricity. Storage bridges that gap: charge when renewables are overproducing, discharge during peak demand. Without storage, PSE either overbuilds generation (expensive for ratepayers) or keeps fossil fuel peakers running (which violates CETA). PSE’s Mt. Si substation sits adjacent to the proposed site, making it a logical interconnection point.

Why are some people opposed to building a BESS in our area?

The proposed facility would use lithium-ion batteries, which carry risks specific to that chemistry:

• Fire: Lithium-ion cells can undergo thermal runaway — an uncontrolled, self-sustaining temperature rise that can cascade through an entire facility. EPRI tracks two failure metrics: a per-project rate (0.3%/yr) and a per-GW rate that scales with facility size. For a 130 MW facility like Cascadia Ridge, the 15-year compound probability ranges from 4.4% to 45% depending on which metric you use. Recent incidents at Moss Landing, CA and Gateway, San Diego required evacuations and EPA-ordered cleanups.
• Toxic emissions: Lithium-ion battery fires produce hydrogen fluoride, heavy metals, and other hazardous compounds. The site is adjacent to Fisher Creek (salmon habitat) and thousands of homes on Snoqualmie Ridge.
• Noise: Lithium-ion systems require active cooling — fans and HVAC running around the clock.
• Alternatives exist: Jupiter Power itself signed a $500M deal with Peak Energy for sodium-ion batteries, which have no thermal runaway, no toxic off-gassing, and use passive cooling. The facility won’t be online until late 2028 — sodium-ion will be commercially available before then.

Residents also raised concerns about proximity to neighborhoods and parks, impacts on property values, and the fact that Snoqualmie’s Comprehensive Plan designates this land for business park and mixed use, not industrial battery storage.

Who will decide whether the proposed BESS project will be approved?

King County. The site is in unincorporated King County, so the City of Snoqualmie has no jurisdiction even though Snoqualmie Ridge residents are the most directly affected. Under the site’s UR zoning and King County Ordinance 19824, BESS is a permitted use — no Conditional Use Permit and no public hearing are required. The main avenue for public input is the 21-day SEPA comment period that opens when Jupiter Power files a new permit application.

Councilmember Sarah Perry (District 3) sponsored the BESS ordinance. The City of Snoqualmie has identified this area as a potential annexation area — if annexed, the city’s Comprehensive Plan would apply.

What happens to a lithium-ion BESS in an earthquake?

The Snoqualmie Valley is exposed to three fault systems — the Southern Whidbey Island Fault (mapped through the valley, M6.5–7.4), the Seattle Fault (M7.0–7.5), and the Cascadia Subduction Zone (M9.0+). Lab testing shows that lithium-ion cells can develop internal short circuits — the initiating event for thermal runaway — from as little as 4mm of compression, forces that even low-magnitude earthquakes (M2–3) can produce. The faults here are capable of M6.5–7.5.

King County’s ordinance requires IEEE 693 seismic qualification, which ensures equipment stays on its mounts. But it doesn’t require modeling the compound hazard: earthquake shaking damages cells internally → thermal runaway → fire → contaminated runoff into Fisher Creek, all while evacuation routes may be earthquake-damaged. No utility-scale BESS has been tested by a major earthquake yet. See the earthquake risk section of our fire risk analysis.

Sodium-ion batteries eliminate this coupling entirely — no thermal runaway means an earthquake can’t trigger a chemical fire.

What can I do?

See Take Action for specific steps — who to contact, what to ask for, and how to make your voice heard.