Over 3.5 million readers this year!

Dinosolar will try again to build solar farm west of Bar Nunn, with commission’s approval

The Sweetwater Solar Energy Project, solar array, south of Green River (Rob Hendry)

CASPER, Wyo. — Renewable energy company Enyo, parent company of Dinosolar LLC, is hoping to resurrect a shelved plan to construct a 240-megawatt-capacity solar array on 2,922 acres of leased private land west of Bar Nunn.

The Natrona County Commission approved an extension of the company’s Conditional Use Permit for the project at its regular meeting Tuesday. The BOCC originally granted the permit in June 2020, when Enyo assumed that Rocky Mountain Power parent company PacifiCorp would agree to purchase the power, and the solar array would be online by December 2023. 

Enyo was “stunned” when PacifiCorp elected not to purchase any solar from Wyoming, attorney John Masterson told the commission Tuesday. However, Enyo is prepared to resubmit when PacifiCorp solicits another round of project proposals in February.

The new timeline calls for construction to take place over 11 months between 2024 and 2025, and for the site to be operational by December 2026. Masterson added that supply chain issues were hampering companies’ ability to acquire solar panels.

The project would bring about $65 million in tax revenue to the county over the expected 35-year life of the solar array, Masterson said.

Though the solar array proposal is the same as two years ago, the commission also approved a permit for the construction of a battery storage system on 25 acres of the original site plan. 

Evelyn Carpenter, co-founder of Solas Energy Consulting, told the commission the addition of the storage component would make the proposal far more attractive to Rocky Mountain Power. It would add to “grid resiliency” by easing demand on the array itself during high-use evening hours. 

Proposed area of solar array in purple. (Dinosolar)

Commissioner Jim Milne asked about the potential for the lithium-ion batteries to explode, possibly causing a chain reaction. Carpenter said each cell is kept in a separate, self-contained enclosure and that an advanced fluid cooling system, monitored 24/7, could divert coolant to any overheating cell. If a cell did succumb to “thermal runaway,” it would likely melt down and off-gas its load of hydrogen and hydrocarbons within the HVAC-equipped enclosure, Carpenter said.

The BOCC approved both permits unanimously, citing the project as a potential boon to the county and a step toward economic diversification and modernizing the county’s aging and ailing energy grid.

The array would connect to the power grid through the Bar Nunn electrical substation to the north and the Casper substation to the south.

“I think this is precisely the kind of economic development and diversification we need in the county,” Commissioner Peter Nicolaysen said.

Initial concerns about the impacts of the solar farm on aviation, wildlife, and the environment were explored by the commission in June 2020. The project comes with the full review of the Wyoming Department of Environmental Quality, Game and Fish, and the approval of the county planning board.