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This article is from the In-Depth Report The Clean Energy Wars

Can Methane Leaks from Fracking Be Turned into Valuable Gasoline?

If test plants succeed, waste methane could fuel vehicles—but the conversion may not offer much environmental benefit
primus-gas-to-gasoline-machine


GAS TO GASOLINE: An early version of Primus's four reactor process to convert syngas swathed in aluminum foil. The machine ran successfully for years.
© David Biello

Cooked by geologic heat and pressure, a molecule of methane embedded in shale deep belowground rockets to the surface, freed by fracking. Captured and put into a pipeline, the tiniest hydrocarbon wafts across the country to a New Jersey office park covered with brick buildings. Behind one of the buildings hides a big machine—a series of metal cylinders, in which parts of the methane molecule will soon be turned into gasoline.
 
If the conversion in this test machine made by Primus Green Energy proves to be as efficient as early results indicate, the methane—which oil companies often burn off or simply release into the atmosphere, worsening global warming—could become an even more valuable resource: liquid fuel. Chemical engineers and biologists are making progress at this and other test facilities and labs, yet it remains unclear if the processes they are trying won’t generate substantial emissions of their own or require more energy than they’re worth.
 
As soon as the methane molecules reach the New Jersey test plant, they are blasted with steam, cracking them into hydrogen and little molecules comprising one atom each of carbon, oxygen and hydrogen. Such synthetic gas, or syngas, is then fed into the first of the cylinders where yet more heat and pressure, combined with the dark art of catalysis, transform it into methanol. That gas flows to another chamber where yet another catalyst helps make it into dimethyl ether, or DME, a slightly larger molecule mixing the atoms of carbon, oxygen and hydrogen. This can be used as a fuel, but is not as valuable as gasoline or diesel, so the DME flows to yet another reactor, where another catalyst converts it into the various hydrocarbons that make up the liquid soup known to the average driver as gasoline. That gasoline flows into a final reaction cylinder that strips out undesirable molecules—a total of four reactors in all. Its final stop is a separator where the gasoline condenses and any spare methane and other leftover gases flow back to begin the process anew.
 
Used this way, 70 percent of the methane molecules that flow onto the property of Primus Green Energy in Hillsborough, N.J., end up as a liquid fuel. And that's why the affable geologist George Boyajian, who is a vice president and primary salesman for Primus, has a map of every shale formation in North America—Bakken, Eagle Ford, Marcellus and more—tacked to his wall. Using the natural gas provided by the local utility, Primus transforms methane into valuable sulfur-free gasoline. And it’s just the kind of low-sulfur gasoline mandated by the U.S. Environmental Protection Agency on March 3, making it valuable as a blending component for companies that sell gasoline. The Primus gasoline also happens to be high octane, less corrosive to infrastructure and engines as well as free of the carcinogen benzene, among other desirable attributes.

"The world is filled with shale," Boyajian notes, standing behind his desk in the uniform of an energy entrepreneur: dress shirt paired with jeans and a hard hat. Even more importantly perhaps, Primus hopes to one day have systems small enough to locate at oil or gas wells, which would turn gases that would otherwise be wasted into 500 barrels a day of valuable chemicals or fuels, including diesel for the trucks that rumble up and down the oil fields.
 
In fact, Primus is one of a slew of companies looking to turn the U.S. shale gas bonanza into a new source for liquid fuels to power transportation. In the process the potential scientific solutions might remedy one of fracking's biggest problems: so-called fugitive emissions—the natural gas that gets away from the wellhead or pipeline or is deliberately released or flared to the atmosphere because that is the simplest disposal solution for companies more interested in oil. Methane leaks have contributed to a rising amount of the potent greenhouse gas in the atmosphere and, if unaddressed, could negate the benefits of using natural gas as a fuel to replace dirtier oil and even dirtier coal. Such natural gas conversion technologies "could be used in a distributed way," U.S. Secretary of Energy Ernest Moniz argues, "to address natural gas flaring at oil wells, which we know is both a problem and an opportunity." Flaring has become so ubiquitous that in satellite images large swathes of the state of North Dakota now light up the night from a sprawling oil field that glows as bright as Chicago.
 
The idea is to help wean the U.S. off oil, and make a tidy profit at the same time because of the low cost of the input: natural gas. At the same time, such transformations could make the problem of flaring—burning or releasing natural gas that is too far away from existing infrastructure for transporting the gaseous fuel to power plants or the like—into a new source of a valuable commodity: liquid fuel, or even hydrocarbons that can be blended into the oil itself. "We've got a lot of cheap natural gas," says materials scientist Dane Boysen, director at the Advanced Research Projects Agency–Energy (ARPA–E) for the Methane Opportunities for Vehicular Energy, or MOVE program. "The question is: What should we do with it?" One of the big ideas to profit is to take gas, which has an energy density of 0.04 megajoule per liter, and turn it into gasoline, which has an energy density of at least 35 megajoules per liter—the best liquid fuel for long-distance trips in today's cars.
 
Steps to success
Primus has its own machine shop, run by chief machinist Aurel Bercovici, who closed his own independent shop to come work full time at the Primus plant. The various reactors and pipes that make up the Primus gas-to-gasoline machine require continual tending and custom parts. "I want to see this project succeed, this gas to gasoline succeed," he says, while wiping the oil from his hands with a rag.
 
Success will require the catalytic insights of chief scientist Howard Fang, who has spent time both at major oil companies and major engine manufacturers. He feeds DME through a specific zeolite mineral to string the carbons together to make the stew of hydrocarbon molecules that are collectively known as gasoline. A more complicated version of the process has been proved to work: Exxon built a methanol to gasoline conversion plant in New Zealand in the 1980s, although the oil giant shut it down when oil prices dropped in the 1990s.
 
Fang thinks he can make gasoline much cheaper than Exxon ever did, by eliminating steps in the process. One possibility for further improvement would be to find a catalyst to go straight from the single-molecule carbon, oxygen and hydrogen to DME. "There are a lot of catalysts to do that," Fang says, as he works in the lab to find the right process to make even more valuable diesel as well.
 
To test such options, 1,500 pairs of cables run into and out of the demonstration machine out back to monitor the thermochemical process. A recent test ran continuously for 720 hours, churning out gasoline—some of which has been used in the company cars, including the CEO's Honda Accord—and data to improve the machine. "Our catalyst was lasting five times longer than had been published in the [scientific] literature," Boyajian claims, potentially saving money.
 
The company is currently looking for a partner to build a larger plant capable of making some 10,000 barrels of liquid fuel per day, and hopes to break ground later this year in the Houston area in cahoots with a "major refiner," according to Boyajian. As it stands, the test machine can already make more than 50 liters of gasoline an hour from natural gas. "We were not working at full capacity," he adds. "We're going to be testing yields now in the next set of runs."
 
But all this still takes a relatively big and expensive machine with multiple chemical reactors. Is there a way to turn gas into gasoline even more cheaply?
 
Better gasoline though biology
Microbes might be the answer for an alternative, cheaper way to exploit stranded or fugitive methane. "Microbes are chemistry," argues Ramon Gonzalez, ARPA–E program director for Reducing Emissions using Methanotrophic Organisms for Transportation Energy, or REMOTE. "They are little bags of enzymes." And those enzymes in their self-contained "bags" could convert methane to a liquid fuel in just one tank, like the fermentation tanks used to turn barley into beer or grape juice into wine. Plus, microbes require relatively mild conditions—nothing caustic, no high pressures or temperatures required, like the Primus plant needs.
 
Those advantages mean it could cost less to use biology. A plant to ferment the sugars from corn into ethanol fuel costs millions of dollars, compared with billions of dollars for the biggest natural gas conversion plants. As a result, companies like LanzaTech use microbes such as Methylomicrobium buryatense to explore fermenting natural gas into liquid fuels or various Clostridium to make ethanol from industrial waste gases. LanzaTech is even building a pilot plant to do just that with Baosteel on the outskirts of Shanghai, potentially producing as much as 380,000 liters of ethanol per year from the off-gases of steel production.
 
There are drawbacks: For one, biology is slow. What it takes a microbe hours or days to do can be done in a chemical reactor in minutes or seconds. And fermenters cannot be built beyond a certain size: biology dictates that beer or wine vats do not grow to stadium-size. "Bugs don't scale," Boyajian argues.
 
Microbes can also be just as polluting as the end-use engine, giving off CO2 when munching methane, and thereby losing half the energy embedded in the chemical bonds of the original gas. Gonzalez and his fellow scientists hope to get around that by engineering the various pathways microbes use for conversion and eliminating inefficiencies. But it will be years before microbe produced fuel will appear at the gas pump, Gonzalez admits.
 
But the thermochemical companies also have a chance at making a one-step process for converting natural gas to valuable products. For example, Ceramatec is using ARPA–E funding to convert methane into benzene in just one cylinder. That benzene can then serve as a feedstock for other products, like plastics. S. Elangovan, Ceramatec's project manager for such fuel processing, is also trying to scale down a gas-to-liquids chemical conversion process known for nearly a century, although the company's current iteration at a lab in Utah is only capable of producing one quarter of a barrel of liquid fuels per day.
 
Pollution solution
The original promise of many of these technologies, including Primus's, was not to convert natural gas into liquid fuels—it was to turn waste wood or energy crops like switchgrass into clean, renewable liquid fuels to replace petroleum. In fact, Fang spent his early years at the company perfecting such a process to turn biomass into an energy-rich gas that could then be fed into a version of the Primus gas-to-gasoline machine. "Natural gas is not true green," Fang admits, "there is no benefit in greenhouse gases." That's because the gasoline from natural gas, when burned, still ends up as atmospheric carbon dioxide, trapping heat and exacerbating climate change.
 
Of course, biomass-to-gasoline could still happen, but only if the feedstock is as cheap or cheaper than natural gas. "If you have syngas, we want to talk to you," Boyajian says, whether it's from gasified city trash or cheap natural gas from fracking. "We see natural gas as a great opportunity to get to biofuels."
 
Other companies, such as SunDrop Fuels, hope to mix the two ideas, using natural gas paired with biomass to make the resulting fuel. Yet other companies are feedstock agnostic, even going so far as to explore the use of coal. After all, if natural gas is converted to liquid fuel on a broad scale, supplies predicted to last a century at present consumption rates could be used up in a few decades or less. "Don't fall in love with a feedstock," LanzaTech CEO Jennifer Holmgren warns, "they'll break your heart."
 
As it stands, natural gas–based gasoline can be used to dilute more sulfurous or otherwise polluting gasoline derived from petroleum, helping meet the EPA's new antipollution rules. But once the fuel is burned it's no better than burning the gas in a flare at the wellhead from a climate change perspective, although in the interim it has provided the power to move a vehicle.
 
And then there are already plans, like those in China, to go from coal to syngas to gasoline. "You cannot do coal," Fang argues, swearing off the conversion process of turning the abundant but dirtiest fossil fuel into liquid fuel—and an even greater proportion of greenhouse gas pollution. From a climate change perspective, Fang notes, such coal to gasoline "would be suicidal."

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