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Studies · CA Air Quality · Investigation 10

Should We Just Retire the Worst Plant?

One wood-fired biomass plant — DTE Stockton — causes 33% of all facility-level PM2.5 deaths in California. Its social health cost is $56.42/MWh, roughly twelve times higher than the next-worst gas plant. Retiring this single 50 MW facility yields $830M in 20-year net benefits — from a plant that generates less than 0.1% of the state’s electricity.

33%
Of Facility Deaths
$830M
20-yr Net Benefit
$56.42
Health Cost / MWh
~12×
vs Next-Worst
NPV Analysis

The Economics of One Retirement

DTE Stockton is a 50 MW wood-fired biomass plant generating 372,300 MWh/year. It emits 1,067 short tons of PM2.5 annually — more particulate matter than all 67 gas plants in California combined. The health cost calculation is straightforward.

Annual Health Benefit
$43.0M
3.71 deaths avoided per year at $11.6M VSL
20-Year NPV (Health)
$659M
Discounted health benefits from retirement
Net Benefit (20-Year)
$830M
Health NPV ($659M) − replacement power ($200M) + avoided fuel/subsidy costs ($371M)

Even after accounting for the cost of replacement power and the facility’s lost revenue, the health benefits exceed costs by $830M over 20 years. The net benefit is positive in year one.

Facility Comparison

One Plant vs All Others

The facility ranking reveals just how anomalous DTE Stockton is. The next-worst facility — Glenarm, a gas plant — has a social health cost of $4.8/MWh. DTE Stockton is $56.42/MWh. The gap is not incremental. It is an order of magnitude.

Facility Fuel Deaths / Year Health Cost / MWh DAC Share
DTE Stockton Wood 3.706 $56.42 35.6%
Glenarm Gas 0.071 $4.8 26.8%
Walnut Creek Energy Park Gas 0.024 $4.3 30.4%
Malburg Generating Station Gas 0.137 $4.0 53.8%
AES Alamitos Gas 0.472 $3.5 18.3%
Haynes Generating Station Gas 0.528 $3.4 19.6%
Magnolia Power Project Gas 0.360 $3.1 31.9%
Valley Generating Station Gas 0.268 $2.9 40.4%
Campbell Power Plant Gas 0.160 $2.8 19.4%
AES Huntington Beach Gas 0.439 $2.7 12.5%

DTE Stockton produces 3.71 deaths per year. All 67 other facilities combined produce 7.5. One biomass plant is a third of the total facility-level health burden.

By Fuel Type

Wood vs Gas: The Numbers

Fuel Type Facilities Deaths / Year Health Cost ($M) Avg $/MWh
Wood 1 3.71 $43.0M $56.42
Pipeline Natural Gas 65 7.25 $84.3M $1.60
Other Gas 1 0.20 $2.3M $0.60
Natural Gas 1 0.02 $0.3M $2.00
Environmental Justice

The Community Impact

DTE Stockton sits in San Joaquin County. 35.6% of the health burden falls on disadvantaged communities (DAC), one of the highest DAC shares in the facility portfolio. The cheapest intervention per avoided death and the one with the largest DAC share are the same plant.

The wildfire-biomass tradeoff. DTE Stockton operates partly under California’s SB 901 and AB 1144, which mandate biomass utilization of forest fuel to reduce wildfire risk. Retiring the plant would require alternative disposal of forest waste. Open pile burning is worse for air quality. Any retirement plan must address this counterfactual — but the magnitude of the health gap ($56.42/MWh vs $1.60/MWh average gas) leaves ample room for alternative solutions.

Finding
DTE Stockton causes 33% of all facility-level PM2.5 deaths in California from a single 50 MW plant. The 20-year net benefit of retirement is $830M. No other single intervention in the portfolio approaches this cost-effectiveness. This is the easiest decision in the analysis.

EPA eGRID facility data · InMAP source-receptor matrix · Di et al. 2017 CRF · Census tract population weighting · VSL = $11.6M (EPA 2024) · 3% discount rate · Replacement power cost = marginal gas generation