Stoneman Generating Station

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Stoneman Generating Station is a retired power station in Cassville, Wisconsin, United States.


Table 1: Project-level location details

Plant name Location Coordinates (WGS 84)
Stoneman Generating Station Cassville, Wisconsin, United States 42.7079, -90.9843 (exact)

The map below shows the exact location of the power station.

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Unit-level coordinates (WGS 84):

  • Unit 2: 42.7079, -90.9843

Project Details

Table 2: Unit-level details

Unit name Status Fuel(s) Capacity (MW) Technology Start year Retired year
Unit 2 retired - 35 MW subcritical - -

Table 3: Unit-level ownership and operator details

Unit name Owner Parent
Unit 2 Mid-America Power LLC DTE Energy Co


In June 2008, DTE Energy announced plans to purchase the E.J. Stoneman Power Plant from Integrys and convert its 50MW of coal capacity to burn wood waste.[1] Dairyland Power Cooperative (La Crosse, Wis.) is purchasing the entire 40 MW output of the waste burning facility to supply its member cooperative consumers.[2]

At the time of DTE's announcement, the company hoped to begin the conversion in 2009.[3] Commercial operation of the 40 MW biomass facility began on Oct. 8, 2010.[4]

The Stoneman Station was owned and brought into service by Dairyland in 1951. Dairyland sold it in the 1990s. Current owner DTE Energy Services converted the Stoneman Station to a biomass facility, selling the energy back to its original owner.[2]

In 2013, the biomass facility was fined $150,000 by the state of Wisconsin for numerous violations of the facility air pollution control permit.[5]

In 2015, it was announced that Stoneman would close by the end of the year following the termination of a power purchasing agreement with Dairyland Coop. During the five year period of biomass operation, neighbors had also complained of charcoal-like soot residue on the homes and vehicles.[6] DTE cited economics of the location for the closure rather than the failure of biomass electrical generation in general. Low natural gas prices benefiting competitors and high transportation costs for biomass fuel were cited as reasons for closure.[7]

The plant was shut down in 2015.[8]

Study finds dangerous level of hexavalent chromium at Stoneman Station waste site

The study "EPA’s Blind Spot: Hexavalent Chromium in Coal Ash," released by EarthJustice and the Sierra Club in early February 2011, reported that the level of hexavalent chromium, a highly potent cancer-causing chemical, at a coal ash site associated with the Asheville Plant was 83 parts per billion.[9] That level is 4,150 times as high as California's drinking water goal, and 66% above North Carolina's groundwater standard. In all, the study cited 29 sites in 17 states where hexavalent chromium contamination was found. The information was gathered from existing EPA data on coal ash as well as from studies by EarthJustice, the Environmental Integrity Project, and the Sierra Club.[10][11][12][13] It included locations in Alabama, Arkansas, Delaware, Florida, Illinois, Indiana, Minnesota, Massachusetts, North Carolina, North Dakota, Nevada, Ohio, Oklahoma, Pennsylvania, Tennessee, Virgina and Wisconsin. In Wisconsin, the Lemberber Landfill coal waste site and Dairyland Power Cooperative's Stoneman Generating Station's ash disposal pond was reported as having high levels of hexavalent chromium.[9]

According to the report, the electric power industry is the leading source of chromium and chromium compounds released into the environment, representing 24 percent of releases by all industries in 2009.[9]

A press release about the report read:

Hexavalent chromium first made headlines after Erin Brockovich sued Pacific Gas & Electric because of poisoned drinking water from hexavalent chromium. Now new information indicates that the chemical has readily leaked from coal ash sites across the U.S. This is likely the tip of the iceberg because most coal ash dump sites are not adequately monitored.[14]

Emissions Data

  • CO2 Emissions: 91,288 tons (2005)
  • SO2 Emissions: 873 tons (2005)
  • SO2 Emissions per MWh: 26.15 lb/MWh
  • NOx Emissions: 175 tons (2005)
  • Mercury Emissions:

Articles and Resources


  1. "Cassville's E.J. Stoneman Coal Plant to be Converted to Burn 100 Percent Wood Waste," Clean Wisconsin, June 2, 2008.
  2. 2.0 2.1 "DTE Stoneman Station Biomass Power Plant Online" Yahoo! finance, Oct. 25, 2010.
  3. "DTE Energy Services Signs Purchase Agreement for Stoneman Power Plant," DTE Energy, May 29, 2008.
  4. "DTE Stoneman Station (Cassville, Wis.)," Dairyland Power Cooperative, accessed September 2012.
  5. "Cassville power plant ordered to pay judgment". Telegraph Herald. Dubuque, IA. June 5, 2013.
  6. Montgomery, Jeff (July 24, 2015). "2nd Cassville power plant closing". Telegraph Herald. Dubuque, IA.
  7. "Midwest utilities plan retirements for coal, gas, biomass power plants". October 14, 2015.
  8. Reber, Craig (January 3, 2016). "Cassville plants power down in 2015". Telegraph Herald. Dubuque, IA.
  9. 9.0 9.1 9.2 "EPA’s Blind Spot: Hexavalent Chromium in Coal Ash" Earthjustice & Sierra Club, February 1, 2011.
  10. "Damage Case Report for Coal Compustion Wastes," August 2008
  11. U.S. EPA Proposed Coal Ash Rule, 75 Fed. Reg. 35128
  12. EarthJustice, Environmental Integrity Project, and Sierra Club, "In Harm's Way: Lack of Federal Coal Ash Regulations Endangers Americans and their Environment," August 2010
  13. EarthJustice and Environmental Integrity Project, "Out of Control: Mounting Damages from Coal Ash Waste Sites," May 2010
  14. "Coal ash waste tied to cancer-causing chemicals in water supplies" Alicia Bayer,, February 1, 2011.

Additional data

To access additional data, including an interactive map of coal-fired power stations, a downloadable dataset, and summary data, please visit the Global Coal Plant Tracker on the Global Energy Monitor website.