Calumet Inc. has commenced operations at the MaxSAF 150 expansion at its Montana Renewables refinery in Great Falls, the company confirmed in its first-quarter 2026 results released May 8. The expansion lifts the site to between 120 and 150 million gallons per year of sustainable aviation fuel capacity and was delivered on the revised schedule and budget Calumet adopted in 2025, when management restructured the project into a streamlined $20 to $30 million build, materially smaller than the capex range associated with the original $1.44 billion DOE loan envelope, though DOE never published a per-milestone breakdown.
The reset matters because it improves the front-end of Calumet’s capital plan, which is to scale toward approximately 300 million gallons of annual SAF capacity upon anticipated completion of the full MaxSAF project in 2028. Whether Phase 2 can be executed at similar capital intensity is the open question. MaxSAF 150 reconfigured existing hydrotreater capacity, and the leap to 300 MMgy is generally understood to require incremental hydroprocessing, hydrogen, and feedstock pretreatment investment that was not in the MaxSAF 150 scope.
“We brought down Montana Renewables for a turnaround and MaxSAF 150 expansion in early March, and successfully commenced operations in early May,” CEO Todd Borgmann said in the company’s results release. Management told investors on the May 8 earnings call to expect what it called a “transformational product mix shift,” delivering a four-to-five-fold increase in SAF volumes on an annual run-rate basis as conditioning and ramp progress through the coming quarters. The underlying hydrotreater will continue to produce renewable diesel as the swing product.
“We brought down Montana Renewables for a turnaround and MaxSAF 150 expansion in early March, and successfully commenced operations in early May.”
The commercial picture behind the ramp is what differentiates this expansion. Calumet executives said SAF contracts in the existing book carry a $1 to $2 per gallon contractual price premium over renewable diesel, a gross contracted spread that management did not characterize as net of LCFS, RIN, or 45Z credit stacking, which accrue differently to SAF and renewable diesel. Most contracts are structured as two-to-three-year evergreens with staggered notice periods, and management told investors the company has not had problems renewing them within its guidance range.
The premium also lands on a recovering, not depressed, renewable diesel baseline. On the May 8 call, Calumet’s COO told investors that biodiesel prices are returning to levels that “incent” supply and the company is guiding to roughly 90% renewable diesel utilization by year-end, while Borgmann described the current environment as “one of the strongest margin environments we’ve seen across both traditional and renewable energy markets.” The SAF premium is therefore additive to a tightening RD market, not a hedge against a weak one.
Where the headline numbers need a closer read is the segment EBITDA. Montana Renewables reported $10.2 million of “Adjusted EBITDA with Tax Attributes” in Q1 2026 versus $3.3 million in Q1 2025, but the figure is dominated by $22.5 million of 45Z Clean Fuel Production Credits generated in the quarter (Q1 2025: $16.9 million). Stripping out tax attributes, the segment remained EBITDA-negative in both periods, and Calumet attributed part of the shortfall to planned expansion downtime. The year-on-year improvement is therefore primarily a function of larger 45Z credit generation rather than a step-change in cash operating margin, and Q2 will be the first quarter where MaxSAF 150 output, SAF contract premiums, and 45Z generation all flow through together.
The ramp lands at a moment when several US SAF projects on different technology pathways have slipped. Gevo deprioritized its DOE loan participation for Net-Zero 1 and pushed final investment decision to late 2026, though that is a greenfield alcohol-to-jet build, structurally different from Montana Renewables’ brownfield HEFA retrofit. The more direct comparison set for HEFA-based US SAF capacity remains small. Montana Renewables already has commercial cover for expanded output through its 70 million gallon offtake agreement with World Energy signed earlier this year.
For airlines, fuel buyers, and policy watchers, the watch item is whether the $1 to $2 per gallon contractual SAF premium holds as uncontracted barrels test the spot market and as 45Z-driven renewable diesel economics continue to evolve. If it does, the case for advancing Phase 2 toward the 300 million gallon ultimate target on similar capital intensity strengthens considerably.
