Patrick Gruber, chief executive of bio-fuels producer Gevo, got an investor cold shoulder this week.

Gevo has reached sales agreements with Japan Airlines, Delta, British Airways and SAS and other airlines for its next-generation fuel. But the firm surprised investors Monday morning when it sold $150 million in equity at $4.50 a share, with warrants that could double the take to close to $300 million.

Gevo's value dropped 33% this week to about $3 per share, down about 65% from its 52-week high of $9.65. That compares with a 20% overall decline of the Russell 2000 index of small companies over the past year.

"No math justifies our current stock price," said Gruber, a University of Minnesota-trained Ph.D. in biochemistry who once ran Cargill's green-technology business. "The decline in price is disproportionate. We need to have enough money on the balance sheet" if the economy takes a downturn as some have predicted.

Gruber, 62, who grew up in St. Paul, has developed a thick skin since he was recruited in 2007 to start Gevo. He has diluted existing investors numerous times over the years to develop its isobutane-based fuel and raise capital necessary to build an aviation fuel plant in South Dakota.

Gevo operates an upgraded ethanol plant in Luverne that demonstrates its low-carbon process to a growing list of airline and industrial customers seeking lower-carbon fuels. It appeared ready for takeoff last year.

The stock had crossed $10 as the Biden administration and increasing numbers of corporations embraced a lower-carbon economy amid weather and financial disasters linked to climate change and shareholder demands that the U.S. lead the world to a cleaner economy.

At the same time, Gevo has drawn significant investor ire with mostly disappointing results over a decade as a public company. Still, analysts at Stifel Financial, Noble Capital and H.C. Wainwright maintained projections last week that Gevo will be worth $11 to $18 per share within six to 12 months.

Derrick Whitfield of Stifel said in a note to investors this week that he remains bullish on Gevo because it has the capital to start construction on its first full-scale production plant this year. It already has multi-year contracts from major airlines and others worth $30 billion that will help finance another five plants, as well as lucrative contracts with ethanol suppliers and feed companies. The residual feed-corn mash left after refining also can be used as a high-protein, low-carbohydrate animal feed.

Gruber notes that the South Dakota plant and subsequent plants will be powered by wind and agricultural waste. And that business sentiment is driving the deals the company is booking.

The concern in the country and the pressure on companies to reduce emissions increased under the Trump presidency and continues. Corporations including once-recalcitrant oil companies have increasingly concluded that climate change will prove disastrous if left unchecked. They are under stakeholder pressure.

The Deloitte Economic Institute reported in January that inaction on climate change could cost the U.S. economy $14.5 trillion by 2070. Conversely, the report concluded that the U.S. would gain $3 trillion if it opts for carbon-reducing, economy-building action over the next 50 years.

"Delta Airlines and other companies are getting sentiment from shareholders and others that they can't escape accountability for their fossil-based carbon pollution," Gruber added. "And it will take years of deploying capital assets to get ahead of this."

Gruber, who dismisses the concerns of those who claim there is a food vs. fuel tradeoff, said Gevo will actually produce more high-quality feed, as well as fuel.

He notes that farm animals produce a small amount of greenhouse gases while petroleum-based fuels produce about 70%. Diverting more carbohydrates to make alcohol-based fuels should produce higher-oxygenate, cleaner burning fuel and also depress oil demand.

"The ethanol industry already produces a better feed product," Gruber said. "You get about the same amount of protein and oil per acre [after the refining process]. And our farmers in South Dakota and Minnesota are shifting to low-and-no-till farming. Less emissions.''

Gevo plans to build several net-zero carbon plants to make aviation and other fuels powered by green energy that should top 1 billion gallons by 2030. It has announced take-or-pay contracts of $200 million-plus annually, including with British Air and Delta.

Gruber, who moved to Colorado in 2005 from Cargill for a two-year turnaround of another company, signed on with Gevo in 2007.