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7 FEBRUARY 2020 • VOL 367 ISSUE 6478 617

PHOTO: GRANT STREM

T

his month, on the frozen plains of

Saskatchewan in Canada, workers

began to inject steam and air into

the Superb field, a layer of sand

700 meters down that holds 200 mil-

lion barrels of thick, viscous oil. Their

goal was not to pump out the oil, but to set

it on fire—spurring underground chemi-

cal reactions that churn out hydrogen gas,

along with carbon dioxide (CO 2 ). Eventu-

ally the company conducting the $3 million

field test plans to plug its wells with mem-

branes that would allow only the

clean-burning hydrogen to reach

the surface. The CO 2 , and all of

its power to warm the climate,

would remain sequestered deep

in the earth.

“We want to launch the idea

that you can get energy from

petroleum resources and it can

be zero carbon emissions,” says

Ian Gates, a chemical engineer

at the University of Calgary and

co-founder of the startup, called

Proton Technologies.

Markets are growing for hy-

drogen as a fuel for power, heat,

and transport, because burning

it only releases water. But most

hydrogen is made from natural

gas, through a process that spews

carbon into the air, or by elec-

trolyzing water, which is pricey.

Proton Technologies says it can cut costs by

relying on oil reservoirs shunned by drillers

because they are water-logged or because

their oil is too thick. “Someone’s abandoned

liability becomes our hydrogen field,” says

CEO Grant Strem, who bought the Superb

field out of bankruptcy.

Geoffrey Maitland, a chemical engineer at

Imperial College London, says he is a “great

fan” of the concept, which treats the oil res-

ervoir as a hot, naturally pressurized reactor.

“This chemistry is well-proven at the surface,”

he says. “The challenge is controlling these

processes several kilometers underground.”

Industry has experimented for decades

with underground burning, also known as

fire flooding. Fed by air or oxygen pumped

into the ground, the fire releases gases

that can push oil toward wells, and its

heat can soften tarlike bitumens and other

heavy oils, making them easier to pump.

In the early 1980s, fire-flooding tests on an

oil field called Marguerite Lake, in Cana-

da’s vast oil sands, produced substantial

amounts of hydrogen as a byproduct. No

one cared very much at the time, but the

finding sowed “the seed of the idea,” Gates

says. “What if we only produce hydrogen

out of the reservoir?”

In a 2011 paper in the journal Fuel, he

and his colleagues sketched out how it

could work. The first step would be to use

steam to heat a reservoir to 250°C or so and

add air or oxygen to touch off combustion.

The heat “cracks” the oil’s long hydrocarbon

chains into smaller pieces and produces

small amounts of hydrogen. But if the fire

reaches temperatures above 500°C, injected

steam or water vapor from the hot reservoir

itself will react with the hydrocarbons to

make syngas: a mixture of carbon monox-

ide and hydrogen. Adding more water to

the syngas sets off a final reaction that pro-

duces CO 2 and more hydrogen.

The main obstacle will be raising tem-

peratures above 500°C with in situ combus-

tion, which is “complicated and not easy to

control,” says Berna Hascakir, a heavy oil

reservoir engineer at Texas A&M University,

College Station. Gates says the reactions

can still proceed below 500°C, just less ef-

ficiently. “Ideally, we’d like to get hotter,” he

says. “But those temperatures are fine to

produce meaningful amounts of hydrogen.”

Another challenge is separating the pro-

duced hydrogen from the CO 2 and other

impurities in the mix, such as toxic hydro-

gen sulfide. Strem says the company will

use thin membranes made of palladium

alloys, which will decompose hydrogen

gas into individual hydrogen atoms. Those

atoms will diffuse through the metal lat-

tice, then combine to form hydrogen gas

again on the other side. But palladium

membranes can be fragile and finicky, even

when used at the surface, notes Jennifer

Wilcox, a chemical engineer at Worcester

Polytechnic Institute. “When doing every-

thing underground, it’s difficult

to have control.”

For now, Proton Technologies

will use their membranes at the

surface and vent the separated

CO 2. But if the company can raise

roughly $50 million for the next

field test, Strem would like to

test the membranes deep in the

wells. He also wants to buy an air

separation unit and inject pure

oxygen into a reservoir, which

would make it a hotter and more

efficient reactor. He hopes to

produce commercial amounts of

hydrogen in the coming months

and says the company could

eventually produce the gas for

between 10 and 50 cents per

kilogram—significantly cheaper

than current sources.

The vast majority of the

world’s produced hydrogen is used to

refine petroleum products and make

ammonia fertilizer. But the market for hy-

drogen as a green fuel is growing, says Ken

Dragoon, executive director of the Renew-

able Hydrogen Association. In pilot proj-

ects, utilities are injecting small amounts

of hydrogen into natural gas pipelines for

home heating and appliances. In transpor-

tation, he says, fleets of trains, buses, and

forklifts are turning to hydrogen fuel cells,

which offer a longer range and much faster

refueling than the other green alternative,

electric batteries.

Dragoon, an advocate for renewable hy-

drogen made with electrolyzers, would be

happy to see a competitor like Proton Tech-

nologies. “We need everything we can,” he

says. “If it’s safe, and it produces a climate

neutral fuel, more power to them.” j

Injection wells at the Superb oil field in Canada. To make hydrogen, workers

heat the reservoir with steam and feed it air, setting off underground oil fires.

By Eric Hand

E N E R GY

Underground oil fires liberate carbon-free fuel

Company ignites heavy oil fields to make green hydrogen while leaving carbon trapped

NEWS | IN DEPTH

SCIENCE sciencemag.org

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