ClearFlame, backed by Bill Gates, retrofits diesel engines for cleaner fuel


When Julie Blumreiter and BJ Johnson met as Mechanical Engineering PhDs. students at Stanford University’s Advanced Energy Systems Laboratory, their advisor, Professor Chris Edwards, gave them advice: never forget that the world is diverse and energy is a global issue.

Yes, we have to achieve sustainability, he told them. But there are nearly a billion people around the world who lack basic access to electricity, and few things improve the quality of life in these communities as much as access to diesel engines. Diesel trucks connect them to food and other essentials; diesel generators provide light and cooling.

“And so what we decided to do as a company was to decouple the economic value of the diesel engine from its environmental challenges, which are not associated with the engine, but are in fact challenges related to the fact that the engine currently requires petroleum-based diesel fuel,” says Johnson, CEO of ClearFlame Engine Technologies, the Geneva, Illinois-based startup he and Blumreiter founded in 2016.

In other words, they wanted to power a “diesel” engine with another fuel that was cheap, plentiful, and clean.

In the six years since its inception, ClearFlame has done just that, modifying diesel engines to run on low-carbon fuels like ethanol and methanol, drastically reducing emissions (and possibly be mileage costs) in the process.

In October 2021, ClearFlame raised a $17 million Series A funding round led by Breakthrough Energy Ventures, founded by Bill Gates, and including agricultural vehicle manufacturer John Deere. And this month, ClearFlame announced that it had signed agreements with truck retrofit companies to add its technology to existing diesel engines, and had rolled out its first pilot fleet trial with an ethanol-powered ClearFlame truck. .

Along the way, ClearFlame got into a tense climate change debate about whether an internal combustion engine can ever be considered eco-friendly in a world that has electric cars and whether it’s arguable to turn food into fuel.

dirty engines

Trucking needs to be decarbonized – that’s not up for debate. Around a quarter of global CO2 emissions are attributable to transport. Of that, about 45% comes from passenger vehicles, an industry already in the midst of a historic transition to electric vehicles. Another 30% of those emissions come from trucking, an industry that has so far failed to electrify. Electric trucks have made inroads over short to medium distances, but they haven’t for the longer hauls (over 100 miles) that make up 70% of US freight.

Long-haul truck companies complain about the short range and long refueling times of electric trucks. The newest Volvo VNR Electric semi advertises a range of 275 miles, while the Freightliner eCascadia travels 230 miles; both take 90 minutes to achieve an 80% change. Diesel trucks, on the other hand, can travel 1,000 miles per tank (though drivers can’t go that far without resting) and fill up in 20 minutes.

Alternative fuels

In the Stanford lab, Johnson and Blumreiter proved that if you ran a diesel engine hotter than normal, the engine could run on a whole range of low-carbon liquid fuels like ethanol, methanol and gasoline. ‘ammonia.

“The fundamental discovery was that we could run a diesel engine, getting the same performance, with any fuel,” Blumreiter explains. “This allows us to choose fuels based on desirable attributes other than their ignition characteristics, such as cost, regional availability, carbon intensity, or cleanliness of combustion.”

ClearFlame founders Julie Blumreiter and BJ Johnson.

Courtesy of ClearFlame

Getting the diesel engine to run hotter was the trickiest part. Low carbon fuels like ethanol and methanol ignite at higher temperatures than diesel, so if used in a normal diesel engine they would not burn and the engine would sputter.

To solve this problem, in 2017, Johnson and Blumreiter left Stanford at Argonne National Laboratory in suburban Chicago. There they joined a new program called Chain Reaction Innovations that had been set up to bridge the so-called “valley of death” between idea and proof of concept for startups in the manufacturing and technology sectors. energy.

They spent the next two years experimenting with how to modify a Caterpillar test engine to prove their concept in a real environment. In the end, Blumreiter and Johnson made the diesel engine hotter by modifying 10-15% of the parts. For example, they removed much of the traditional cooling components so it would be hot enough to ignite low carbon fuels.

“We changed some of the air and exhaust plumbing in the engine to let the air and exhaust get hotter in the engine than they otherwise would have,” says Johnson. “And then we changed the fuel injection systems to be compatible with these low carbon fuels, which usually means engineering for lower viscosity.”

With proven science in a driving force, ClearFlame raised $3 million in seed funding in early 2020 led by Clean Energy Ventures, just before the onset of the COVID-19 pandemic.

Take the road

Ethanol is usually made from corn or sugar cane and still has some carbon footprint, including that of the tractors and fertilizers used to grow it. But, according to ClearFlame, running one of the company’s modernized diesel engines on ethanol reduces CO2 emissions by 42% compared to diesel. In fact, the company claims that a ClearFlame engine emits 23% less carbon than battery electric vehicles due to the mix of fuels used to generate electricity on the national grid. And because ethanol is a “short” molecule with two carbon atoms — compared to the 16 in a typical diesel string — a ClearFlame engine produces 99% fewer soot particulate emissions, according to the company.

Courtesy of ClearFlame

Perhaps equally interesting for trucking companies, an external study commissioned by ClearFlame prior to Russia’s invasion of Ukraine found that running a truck with a ClearFlame engine costs eight cents less per mile than a diesel. At the highest diesel price during the war, those savings jumped to 25-30 cents per mile, Johnson says.

Over the past year, ClearFlame has upgraded its first four trucks, Blumreiter says, and now has 35 employees. The company ran trucks on its engines for “tens of thousands” of miles, Johnson says. In September, it announced it had signed deals with Reviva, an engine rebuilder, and Vander Haag’s, a truck service chain, to integrate ClearFlame’s kit into Cummins X15 truck engines and install them in Class 8 trucks, the highest class on American roads.

The ClearFlame upgrade process costs between $40,000 and $50,000. A typical new diesel tractor-trailer costs around $150,000 and has the engine rebuilt (around $30,000) after a million miles. Johnson argues that the extra expense of a ClearFlame upgrade is justified because it pays for itself in 12 to 24 months through lower costs per mile. Vander Haag commercial director Eric Krikke said a refurbishment should take about two weeks.


Not everyone is sure the ClearFlame concept is the best way to decarbonize trucking.

Electric trucks and vans can already cover short and medium trips and their range is expanding, critics say; Also, there is no nationwide network of gas stations that offer pure ethanol. (Blumreiter notes that trucking fleets, which already have diesel tanks installed at their depots, could reuse an already installed tank or install a new one for tens of thousands of dollars, and truck stops could follow: “I expect that to happen, because the cost of liquid fuel infrastructure is so low.”

Courtesy of ClearFlame

There are also philosophical arguments against low carbon fuels like ethanol and methanol. Their use assumes that carbon emissions are acceptable as long as they do not come from pumping fossil fuels out of the ground. But, “hardcore strippers say all carbon is bad,” notes Christoph Stuermer, automotive practice manager at Vindelici Advisors.

Ethanol attracts more direct criticism. “There are fears that this stuff will become so economically viable that growing crops for first-generation biofuels will crowd out food and feed and therefore increase food prices or increase food shortages,” Stuermer said. . “Americans could pay more to put it in their cars than African children could pay to eat it.”

Kyle Teamey, head of BEV’s ClearFlame investment deal, says ClearFlame’s goal is not to design engines for plant-based ethanol, but rather for a host of new light fuels like methanol which can be produced from water, CO2 and renewable electricity. . “New energy vectors are emerging. And that’s why I’m excited about this… We’re not arguing about how best to use cropland, we’re looking at the next phase of market evolution.

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