Comstock Inc., a legacy gold and silver mining company based out of Nevada, began pursuing investments into early stage decarbonization technologies in 2017. Fast-forward to 2025, and the company's subsidiary, Comstock Fuels Corp., is leading the way to woody feedstock-produced liquid renewable fuels by utilizing its revolutionary conversion technology. “Not only are we a producer, but we’re also a technologist,” says Comstock Fuels Director of Business Development Chad Michael Black. “We are the technology that enables the woody biomass to be converted into renewable fuels.” On that list, Black says, is sustainable aviation fuel (SAF).

Far from an overnight success, the foundational patents crucial to Comstock Fuels’ technology and processes were initially filed in 2013, Black says. “There were three companies that were acquired in 2021, so since that time, we’ve been further perfecting the artwork on the patent to go all the way to liquid fuels,” he explains.

The Comstock Legacy 
Comstock Mining was established in 2003 in Nevada, focused on the Historic Comstock District. The District’s legacy dates back to 1859, when over 8 million ounces of gold and nearly 200 million ounces of silver were discovered and mined from 1860-1880. Named the Comstock Lode, the strikes of silver and gold “stretched from Virginia City to Gold Hill to Silver City," roughly two and a half miles, says the Nevada State Historic Preservation Office.  

In 2010, Corrado De Gasperis was inducted into his role as Comstock Inc.’s CEO, and in 2015, he added on the title of executive chairman. Quickly after, with the support of the company board, Comstock began its investments in renewable energy. “In roughly 2017 ... the board made the decision to invest in early-stage decarbonizing technologies, with one of those technologies now being the wood-to-fuel technology that forms Comstock Fuels Corporation today,” Black says.

Today, Comstock Fuels’ technology rivals that of Earth’s natural hydrocarbon formation process. “Our process, it accelerates that process. So, what takes Mother Nature millions of years to create crude oil from organic matter, our process can convert in hours,” Black says. 

The key to this is feedstock availability, Black explains. “The current constraint inside the system is feedstock availability, right? Our technology unblocks that constraint; we utilize woody biomass. Terrestrial biomass makes up roughly 80% of the world’s vegetation, so it’s an abundant supply of feedstock,” he says.

An Evolution Revolution 
There are four key steps to Comstock Fuels’ production process. “The front-end component is separation; that’s pulping and digestion—no different than any pulp and paper facility,” Black explains. “They use sodium sulfate as a solvent; we use butanol as a solvent. That’s the only difference.

“The second step is fermentation—that’s ethanol,” Black says. “The third step is esterification, or fat splitting, creating an ester—that’s biodiesel. And then the fourth step is hydrotreating, which is done at both renewable fuel and petroleum refineries around the world,” he says.

“Because we’re using woody biomass as source material, we have best-in-class carbon intensity (CI) scores, so our finished fuel is around a 15 [CI], prior to any type of green energy, carbon sequestration,” Black continues. “And it’s extremely high yielding. We’re pushing upwards of 140 gasoline gallon equivalents (GGE) ... that's almost double our known competitor from a technology perspective.”

This low-carbon, high-yielding technology is used to access lignin. “Historically, this separation-first mentality, you’ll see other technologies that can claim this cellulose fraction [50%],” says Black. “We take our pulp, we enzymatically convert it into sugar, and then we ferment it into cellulosic ethanol. That ethanol can be converted into SAF, given a number of dehydrating technologies that exist today.”

Black says that Comstock Fuels'  claim to fame is going after the other 50% of the tree—the remaining hemicellulose and lignin. “When these two products combine with the butanol in our front-end digestion, they form a unique blend of hydrocarbons that we call bioleum,” he explains. “Bioleum is suitable, with further treatment, to be a drop-in feedstock for both renewable fuel and petroleum refineries for coprocessing ... When it’s in its biointermediate states, its called bioleum oil, about 18% oxygen, 15 TAN (total acidic number).”

“We also found with a little refinement, we can get that oxygen content down to about one percent,” Black continues. “That bioleum fraction, predominantly SAF range, about 60-70% of the byproduct of the HBO, the hydrodeoxygenated bioleum oil—is sustainable aviation fuel by ASTM standards.”

Despite its advanced results and integrated processes, Comstock Fuels’ technology components primarily use off-the-shelf equipment. “We have a legacy dating back to 2003 with investments in and around lignin conversion technologies. Our front-end system uses an organosolv-separation digestion phase,” Black explains.

The solution: Swedish company RenFuel’s exclusively licensed esterification technology. “It takes any lipid—fat, oil and grease—such as our crude bioleum, mixes it at about a 0.7 to one ratio of fats to bioleum, and then creates a lignin ester, the bioleum oil. Now we have a suitable feedstock to drop in at renewable fuel refineries. That product is geared toward a 100% drop-in sustainable aviation fuel,” he says.

“Today, aviation fuel cannot be dropped in neat; it has to be blended to meet ASTM specs ... and the reason is because the aromatics are normally removed in the process,” Black explains. “Our process keeps the aromatics, so in theory, if there was a pathway approved for 100% drop-in SAF, we would be first to qualify because the aromatics remain in our process.”

Making the Market 
As for its most recent news, Comstock Fuels recently scored a $14 million investment from Marathon Petroleum. Financing is a major roadblock that inhibits many industry hopefuls from finding success. “If you wanted to constantly apply for grants and go from benchtop scale to pilot scale, through commercial demonstration and full biorefinery with the USDA or the U.S. DOE—there’s a pathway for that, and it’s about a 25-year process," Black says. "So, it’s not practical. The deal we recognize is that to meet the grand SAF challenge by 2030, there needs to be $50 billion in capital placed into steel today.” 

Despite this gap, Comstock is confident it can play a notable role in meeting the U.S. Grand SAF Challenge, as well as an internal goal of its own: owning and operating 10 facilities in the next 10 years. Alongside several nationwide scouted states, Black cites three licensees in Australia and one licensee each in New Zealand, Vietnam, Pakistan and three more international sites on the move. 

These sites, above all, require space, water and access to feedstock. Colby Korsun, Comstock Fuels’ site development manager, points to a required 100-200 acres of space, 200,000-250,000 gallons of water on the supply side and 400,000-500,000 gallons of water on the disposal side, both needing the ability to be scaled up by 10 in five years, and 5-10 megawatts (MW) to be scaled up to 50-75 MW in five years, among other requirements. Feedstock in range is also a desirable trait in a potential site. To remedy this, Comstock has contracted Hexas Biomass Inc. for its energy crop, XanoGrass, which Comstock has exclusive access to, except for certain preexisting agreements.

Comstock’s products and technologies apply to several markets, including SAF, the U.S. transportation system and mining. “There’s a major demand in the SAF arena to be able to decarbonize to lower transportation carbonization rates by 2030 and 2050,” Black explains. “What we’re able to do is incentivize whole countries into becoming energy independent ... our technology allows them to tap into terrestrial biomass, which again, is roughly 80% of vegetation that grows around the world.”

This technology and the ability to convert woody biomass as well as purpose-grown energy crops allows the company to control its own destiny,  Black says.

When it comes to competition, from Black's perspective, nobody really benefits. “We want to enable an industry of SAF," he says. "One point of contention that a lot of early adopters want is exclusivity for the technology, and that’s something that we’ve never allowed in the system.

“Right now, the missing link is that everyone’s doing it in their own vacuum,” Black adds. “Where collectively, we don’t believe in competition .... from the technology perspective, it hurts the industry every time something doesn’t work. We love our technology, but we want everyone to gain success.”

Author: Caitlin Scheresky 
caitlin.scheresky@bbiinternational.com