Great River Energy adding fuel oil capacity to Cambridge gas plant to use during big weather events

Minnesota regulators unanimously approved a plan by Great River Energy to convert a natural gas plant in Cambridge to one that can also run on fuel oil, saying the project could help deliver reliable and cheaper power during winter storms like the February 2021 disaster in Texas.

The Minnesota Public Utilities Commission rejected a call from environmental nonprofits for tougher scrutiny. The groups argued that there would be potential environmental impacts of using ultra-low sulfur diesel at the 170-megawatt peaking plant north of the Twin Cities and also possible health risks.

"This record supports a determination that the proposed change would not have significant impacts" on the environment or human health, said Commissioner Valerie Means, a Democrat. "I also think it just makes sense to have another mitigation tool in the event of another Winter Storm Uri," referencing that Texas cold snap.

Great River, a nonprofit cooperative based in Maple Grove, estimated the plant would run on fuel oil fewer than 24 hours a year on average. But the state also reviewed the potential effects of using fuel oil for 75 hours a year, in line with a Uri-type storm.

In filings with the PUC, Great River said extreme cold events are predicted to happen more often in the future even as climate science points to increasingly warmer temperatures in winter.

The utility would need to build a 500,000-gallon above-ground fuel storage tank and another 450,000-gallon water tank. Great River envisions the dual-fuel infrastructure would operate over 30 years.

The Cambridge unit is Great River's only natural gas peaking plant that is not capable of using two fuels.

Great River Energy believes using the fuel oil option would be cheaper than going to the open market for energy when there is a huge storm like a polar vortex.

If the plant ran diesel for 75 hours in a year it would result in 12,829 short tons of carbon emissions, according to a state environmental assessment. That's the equivalent of 58 semi-trailer trucks driving 120,000 miles a year or the annual carbon footprint of 802 average Americans.

The Minnesota Department of Commerce said a project with greenhouse gas emissions below 100,000 tons per year "does not have the potential to result in significant [greenhouse gas] effects." And more broadly, Commerce officials concluded the project won't have significant environmental effects that would require Cambridge to seek a environmental impact statement rather than a quicker environmental review and approval for a "minor alteration" to the plant.

The Laborers' International Union of North America, the International Union of Operating Engineers Local 49 and the North Central States Regional Council of Carpenters supported the alteration at the plant.