Carbon-Capture Projects Are Taking Off. Here’s How They Stash the Greenhouse Gas.
Sixty-five miles off the coastal Norwegian city of Bergen, a drilling rig is punching through layers of mud and rock below the North Sea. The energy firms behind the rig aren’t prospecting for oil or gas. They are searching for a place to stash vast amounts of the greenhouse gases emitted by industrial facilities across Europe.
The Northern Lights project—a $2.6 billion joint venture of
Shell PLC,
TotalEnergies SE, Equinor ASA and the Norwegian government—is one of almost 200 carbon-sequestration projects now in operation or in development around the world, according to the Global CCS Institute, a think tank that promotes carbon capture. When completed in 2024, Northern Lights will be the world’s biggest effort to sequester, or store, carbon dioxide underground.
These projects aim to effectively reverse the impact of fossil-fuel combustion by putting carbon dioxide back into the ground. The greenhouse gas gets pulled from the open air and from industrial facilities that produce electricity, steel, aluminum or cement. If the project is designed and built properly, geologists say, the carbon dioxide can be stored safely for generations.
“We are actually using backwards the same mechanism that has kept oil and gas underground for millions of years,” said
Cristel Lambton,
technical director of Northern Lights. “That’s where we know it is safe.”
Despite the industry’s 25-year record of safe underground storage, such an experiment has never been conducted before on such a massive scale. The risk is that the infrastructure of wells and pipelines eventually leaks, allowing the carbon dioxide back into the atmosphere. Carbon dioxide, which scientists at the Intergovernmental Panel on Climate Change say has warmed the planet nearly 2 degrees Fahrenheit since 1900, needs to decrease if the world is to avoid the worst effects of climate change.
Initiatives like Northern Lights aim to lock away industrial emissions of carbon dioxide before they reach the atmosphere. Others use giant fans to suck in outside air and filter out carbon dioxide, a process known as direct air capture. There are also experimental efforts to use the ocean as a massive carbon-dioxide sink by altering its chemistry. The ventures now under way are showing which technologies and geologic formations are most reliable.
“We want the carbon storage to be permanent, but we want to provide confidence to investors, regulators and other stakeholders,” said Dr.
Susan Hovorka,
senior research scientist at the Gulf Coast Carbon Center at the University of Texas, who has been researching sequestration methods for the past 24 years. “So we want to do surveillance that provides affirmation of the permanence.”
Northern Lights plans to pump carbon dioxide into a layer of sandstone about a mile and a half below the seafloor. There the gas is expected to dissolve in briny water and interact with minerals. After a century, about half of the carbon dioxide pumped into the formation will become part of the rock, according to Dr. Lambton. “The longer the CO2 stays in the reservoir, the safer it becomes,” Dr. Lambton said.
The venture expects to sequester 1.5 million metric tons of carbon dioxide a year when it opens in 2024, eventually reaching 5 million metric tons a year.
One way direct air capture locks away carbon dioxide (CO₂)
Fans suck ambient air into a chamber with
filters that trap CO₂ molecules.
The filters are heated, producing
a stream of CO₂ gas.
The gas is dissolved in water,
which is then piped into rock
formations several hundred
feet underground.
Scientists estimate there
are enough rock formations
like these to hold about
three times as much CO2
as the total that’s been
emitted since the mid-1700s.
The CO₂ reacts with porous rocks.
Over time, it turns into carbonate
stone and is locked away
for thousands of years.
Fans suck ambient air into a chamber with
filters that trap CO₂ molecules.
The filters are heated, producing
a stream of CO₂ gas.
The gas is dissolved in water,
which is then piped into rock
formations several hundred
feet underground.
Scientists estimate there
are enough rock formations
like these to hold about
three times as much CO2
as the total that’s been
emitted since the mid-1700s.
The CO₂ reacts with porous rocks.
Over time, it turns into carbonate
stone and is locked away
for thousands of years.
Fans suck ambient air into a chamber with
filters that trap CO₂ molecules.
The filters are heated, producing
a stream of CO₂ gas.
The gas is dissolved in water,
which is then piped into rock
formations several hundred
feet underground.
Scientists estimate there
are enough rock formations
like these to hold about
three times as much CO2
as the total that’s been
emitted since the mid-1700s.
The CO₂ reacts with porous rocks.
Over time, it turns into carbonate
stone and is locked away for
thousands of years.
Fans suck ambient
air into a chamber
with filters that
trap CO₂ molecules.
The filters are
heated, producing
a stream of
CO₂ gas.
The gas is
dissolved in
water, which is
then piped into rock
formations several
hundred feet
underground.
Scientists estimate
there are enough
rock formation
like these to hold
about three times
as much CO2 as the
total that’s been
emitted since
the mid-1700s.
The CO₂ reacts
with porous rocks.
Over time, it turns
into carbonate
stone and is locked
away for thousands
of years.
Fans suck
ambient air
into a chamber
with filters
that trap
CO₂ molecules.
The filters
are heated,
producing
a stream of
CO₂ gas.
The gas is
dissolved in
water, which is
then piped into
rock formations
several hundred
feet underground.
Scientists
estimate there
are enough
rock formation
like these to hold
about three
times as much
CO2 as the total
that’s been
emitted since
the mid-1700s.
The CO₂ reacts
with porous rocks.
Over time, it turns
into carbonate
stone and is
locked away
for thousands
of years.
Something similar is already happening in Iceland. Since 2021, a carbon-capture plant 30 miles south of Reykjavik has been using 72 massive fans to suck in air, trapping carbon-dioxide molecules in giant filters and then heating the filters to yield a stream of carbon-dioxide gas. The gas is dissolved in water and then piped hundreds of feet underground, according to Ólafur Teitur Guðnason, a spokesman for Carbfix, an Icelandic firm that operates the facility with the Swiss firm Climeworks.
“The water seeps through the pores in the basaltic rock, reacts with the metals in the rock and quite literally turns into stone,” Mr. Guðnason said.
Not everything has gone smoothly. Plumes of sulfuric acid emitted by a nearby geothermal plant have corroded the plant’s fan blades, according to
Carlos Härtel,
chief technology officer of Climeworks.
“The plant is a complex machine,” Dr. Härtel said of the facility. “I’m quite convinced that we will find more surprises if we bring it into a tropical region or an arid region. What will happen if I put this thing in the middle of the desert in the Middle East?”
In Texas,
Occidental Petroleum Corp.
and its partners have started construction this month on a plant to eventually capture a million metric tons of carbon dioxide from the air and inject it into underground formations.
Another challenge is securing sources of renewable energy. If power generated by coal or other fossil fuels is used to run the facilities, the carbon-removal equation doesn’t add up.
Some scientists believe seawater may be the best place to store carbon dioxide.
One idea for stashing more carbon in seawater involves the creation of huge offshore kelp farms. As kelp absorbs the carbon dioxide that fuels its growth, it becomes so heavy that it eventually sinks, dragging large quantities of carbon down to the seafloor, where it remains for decades.
Other ideas include planting seagrasses and other marine plants that naturally capture carbon dioxide and treating seawater to raise its alkalinity. High alkalinity boosts the water’s ability to absorb carbon dioxide from the air. The latter approach is under development by a handful of firms, including Planetary Technologies, a startup in Dartmouth, Nova Scotia.
Ocean-based carbon-removal techniques are in early stages of development and still need to be evaluated for effectiveness and potential risks, according to a 2021 report by the National Academies of Sciences, Engineering, and Medicine.
For all the optimism among some entrepreneurs and engineers, carbon sequestration so far has removed only small amounts of carbon dioxide from the atmosphere. The tally for 2022—about 43 million metric tons, according to the Global CCS Institute—is a tiny fraction of the 10 billion metric tons that the IPCC says needs to be removed annually by 2050.
“If we’re not talking about the billion-ton scale, it’s not worth talking about at all,” said
Robert Jackson,
chair of the Global Carbon Project and professor of earth system science at Stanford University. “We must have hundreds of thousands of these kinds of projects to make a real dent in our climate.”
Some climate scientists worry that the growing investment in carbon sequestration might distract from continuing efforts to curb emissions of carbon dioxide and other heat-trapping gases from power plants, factories and tailpipes.
“It’s easier to avoid making the mess in the first place than it is to clean it up afterwards,” said
Ken Caldeira,
senior scientist emeritus at the Carnegie Institution for Science’s Department of Global Ecology.
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