In Kansas, Abengoa built a biorefinery to process 325,000 tons of crop residue a year and produce 25 million gallons of cellulosic ethanol

For quite some time now, climate documentaries have highlighted the promise of turning farm residue into fuel. It almost seems like something from a fairy tale. However, it was real in the flat, windy town of Hugoton, Kansas, and it stayed real for a little over a year, before economics and corporate collapse caught up with it, which is the part of the story that never gets its plaque in the history of climate change.

According to theU.S. Department of Energy, the Spanish energy firm Abengoa established a commercial-scale biorefinery at Hugoton that wasbuilt with the capacity to convert up to 325,000 dry tons of crop residues into roughly 25 million gallons of cellulosic ethanol every year while a cogeneration unit supplies up to 21 megawatts of power to the facility, which it uses for its own operations with still enough to spare. That implies roughly 77 gallons of ethanol per dry ton processed at full capacity, which sits squarely within the 70–80 gallon-per-ton range typical of enzymatic hydrolysis cellulosic ethanol, so the two nameplate figures are consistent with each other. This was one of the closest attempts to demonstrate the viability of "second generation" biofuels derived from crop waste rather than.

The pitch: turning leftover stalks into liquid fuel


It was not easy science. Accounts of the underlying testing vary depending on the source: the DOE states that Abengoa's enzyme hydrolysis technology was evaluated for more than 30,000 hours at pilot scale and over 6,000 hours at demonstration scale (roughly 36,000-plus hours combined), while Abengoa's own CEO, at the plant's 2014 opening, put the combined pilot-and-demonstration total at "roughly 40,000 hours." Enzyme hydrolysis technology is the chemical reaction that converts tough plant fiber to fermentable sugar. This was not some backyard science experiment; it was supported by a cost share grant of $97 million and a $132.4 million loan guarantee by the government, all under the Obama administration's plan to advance next-generation biofuels. The grand opening of the Hugoton plant in October, 2014, was attended by both the current U.S. Secretary of Energy and the Kansas' governor.

A mandate the industry was never going to hit

That is where the broader policy challenge becomes clear: Washington had been warned this was a long shot. A committee of the National Academy of Sciences, reported by Purdue University, concluded a few years ago that the federal Renewable Fuel Standard's goal of 16 billion gallons of cellulosic biofuel by 2022 is probably doomed to failure, since cellulosic technology was quite different from 30-year-old corn ethanol infrastructure; it had no proven commercial-scale track record and no cost-competitive feedstock supply chain on which to rely.

The prediction proved to be not so very inaccurate. In 2018, Cui et. al, in their peer-reviewed paper titled “Strategies for near-term scale-up of cellulosic biofuel production using sorghum and crop residues in the US,” published in the journal Environmental Research Letters, found that levels of renewable fuels fell to 80% of 2017 goals, but cellulosic biofuel was only at 5% of its 2017 goal. Hugoton was soon cited as a case study in that gap. But only a year after opening, Abengoa’s parent company entered bankruptcy, and production at the Kansas plant was suspended in December 2015, leaving approximately 50 local employees unemployed, according to a 2016 DTN Progressive Farmer report.

The plant sat idle after a Chapter 11 auction in which an Illinois biofuel company, Synata Bio, purchased it in late 2016 for $48.5 million: a small fraction of the estimated $230 million that may have been spent constructing the plant. That idle stretch didn't last forever, though: Synata sold the site in February 2019 to High Plains Bioenergy, which later renamed itself Seaboard Energy and converted the facility into a renewable diesel plant, retrofitting it to run on animal fats and vegetable oils rather than crop residue. That new plant has since come online: a different fuel, a different feedstock, and a different company, but no longer an empty building.

The takeaway

All this doesn't mean that crop-waste fuel is a dead end, however, because researchers are working to develop cheaper feedstocks and better economics for precisely this reason. These, however, are two vastly different sentences and it's possible to have a technology that is scientifically right but financially premature, as Hugoton demonstrates. The Kansas cornfield, once the sole source of energy, is a cautionary footnote rather than a failure story, and it's a reminder that for a generation on the whole watching billions of dollars get funneled into hydrogen hubs, sustainable aviation fuel, and carbon capture, is a problem the industry still hasn't quite solved.