Tag Archives: carbon capture and storage

A deep look at carbon capture and storage (CCS) and its role in the climate crisis

Carbon Capture and Storage (CCS) is the process of capturing carbon dioxide (CO2), a greenhouse gas, and depositing it somewhere it will not reach the atmosphere again — typically in a suitable geological formation. The goal is to reduce the amount of greenhouse gases in the atmosphere and limit (or even reverse) man-made climate heating.

Does it work?

It’s not science fiction. The technology already exists and several projects are already underway. The carbon dioxide is typically extracted from a single point source (like a cement factory or a fossil fuel facility), and injected into a porous structure where the CO2 can be absorbed without leaking back into the atmosphere. Carbon dioxide can also be absorbed from the air, although the efficacy of this process is much lower.

Carbon capture and storage can reduce the emissions of a plant by up to 90% and when coupled with other technologies, CCS can even lead to negative emissions.

The technology is regarded by many researchers as a key tool in our fight against global warming and greenhouse gas emissions as it is not only a way to reduce our emissions, but maybe even to grab some of the greenhouse gases already present in the atmosphere and store them. However, CCS comes in many different forms and, at this moment, there are only a handful of operating CCS projects in the world.

Simply put, it works — the physics of the process is valid. But whether or not CCS will really be used on a wide scale and help us keep climate change in check is a very different question.


The planet is heating up. Over the past century, the planet’s average surface temperature has risen by about 2 degrees Fahrenheit (a bit over 1 degree Celsius) — a change driven largely by increased carbon dioxide and other man-made emissions into the atmosphere.

We won’t get into the details of how we know climate change is happening and that it’s caused by mankind. All the available figures and scientific evidence point in this direction. Greenhouse gas emissions have increased steadily since 1890, and as a result, temperatures are rising. The problem is very real and burying our head in the sand won’t help one bit.

If we want to truly manage this crisis, we need to reduce our emissions, achieve net zero emissions, and, ultimately, find ways to revert previous emissions. The good news is that CCS can help with both.

Right now, society most focused on producing renewable energy to replace polluting and carbon-intensive fossil fuels. In truth, it’s not just just the environmental aspect of it, renewable energy is already cheaper in many parts of the world (but that’s a different story). Important as this may be, it’s not enough on its own.

A substantial part of our emissions comes from other industrial activities (like cement factories, for instance) which are extremely hard to decarbonize, and it’s not like all fossil fuel power plants will disappear overnight — we need to reduce emissions from them in the meantime. This is where CCS can come in and make a difference.

However, we can’t just capture carbon dioxide, put it in a box and wash our hands, it just doesn’t work that way. You can’t build a carbon storage factory. Luckily enough though, nature has done that herself.

Geology to the rescue

Some subsurface geological features are excellently suited as carbon storage sites. Some brine-filled pores in sandstone formations, or other similar structures sealed by a natural and impermeable caprock such as a shale or clay. Essentially, you need a porous rock to inject the carbon in, and impermeable rocks to act as a seal around it.

In some contexts, carbon storage has been used for several decades (most notably for enhanced oil recovery), but as a tool to tackle global heating, it’s a relatively new concept. For many current CCS projects, the technology used to lock CO₂ deep underground is the same technology used to enhance oil reservoirs. In one oil field (called Sleipnir), some 23 million tons of CO₂ have been injected underground. In the case of Sleipnir, the positive effect of injecting CO₂ is counterbalanced by the extraction (and subsequent burning) of oil. But what if we could just have the positive effect and not do the oil part? That’s pretty much how the idea of carbon storage emerged.

It’s been actively researched in the US since 1997, but the technology first took off in Norway in the 1980s. Although the basic principle is still the same, CCS as a field of science has grown and developed massively since. CCS publications and studies have increased exponentially in the past 20 years, with international collaboration spurring multiple projects. Still, as of 2019, there are only 17 operating CCS projects in the world, capturing 31.5Mt of CO₂ per year, of which just 3.7 is stored geologically. Compare that to the 5.1 billion metric tons of energy-related carbon dioxide the US emitted in 2019 alone — it takes the US just a couple of days to emit more CO₂than is stored year-round in the entire world.

But this doesn’t mean that CCS can’t grow. The latest IPCC Assessment Report on Mitigation mentioned CCS 35 times in the summary for policymakers. The International Energy Agency has repeatedly said CCS is a key technology for mitigating climate change. More and more, researchers are looking at CCS as one of the key ways to address some parts of our greenhouse gas emissions.

At the very least, the geological potential is there. The US National Energy Technology Laboratory (NETL) reported that North America has enough storage capacity for more than 900 years worth of carbon dioxide at current production rates. Even though there is some uncertainty regarding potential long-term leaking, there’s still more than enough room for the world to dump its carbon underground.

Location, location, location (and technology)

Carbon capture and storage is most effective when it’s applied at point sources such as a single factory or a single storage site — it’s far less effective when dealing with multiple, smaller sources. This is what makes it an excellent technology for heavy-emission industries.

Exasmple of how CCS can work at a biomass plant. Image credits: Wiki Commons.

There are three main types of carbon capture and storage for industrial facilities:

  • post-combustion capture is the most widely used form of carbon capture and storage. It essentially refers to capturing CO₂ from a flue gas generated after combusting a carbon-based fuel, such as coal or natural gas. A number of different techniques are used ,and post-combustion capture is especially interesting for researchers because existing fossil fuel power plants can be retrofitted to include CCS technology in this configuration.
  • pre-combustion capture is widely applied in fertilizers, gaseous fuel (H2, CH4), and power production. The advantage is you also obtain hydrogen which can be used as a fuel. However, retrofitting plants to accommodate pre-combustion capture is challenging and this is mostly an option for new plants.
  • oxy-fuel combustion, where the fuel is burned in oxygen instead of air. This results in a flue gas that is mainly CO₂ and water.

There are multiple technologies for separating CO2, becoming more and more efficient every year. But after it’s separated, the CO2 must be transported. This is most easily done via pipes (and has been done before). For instance, there were approximately 5,800 km of CO2 pipelines in the United States in 2008, and a 160 km pipeline in Norway used for enhanced oil recovery.

After it’s separated and transported, it is injected into a suitable geological reservoir.

Negative emissions — taking carbon from the atmosphere

So far, we’ve mostly focused on using CCS for factories, as a way to reduce emissions. But CCS can also be used as a way to revert emissions — or, as researchers put it, to produce negative emissions.

Cement amounts for about 8% of the world’s greenhouse gas emissions. Image credits: Kåre Helge Karstensen, SINTEF.

The underlying principle is straightforward: you extract carbon from sources in the Earth’s biological cycle and inject them on the ground. This way, you’re not just reducing the carbon you’re outputting, you’re essentially eliminating some of the already existing carbon. So you would take something like wood chips or biological waste such as manure and inject the carbon from it to a geological storage site.

But it can get even more interesting than that. In a recent study, researchers discovered a way to pull carbon dioxide from the atmosphere and turn it back into coal. This approach is actively being researched by fossil fuel companies, who are looking for a way to maximize returns. However, in order for this to truly have a net positive effect, the subsequent burning of the resulting coal would also have to be captured.

Perhaps the most exciting development comes from Iceland, where researchers found a way to extract CO2 and mineralize it into rocks. They’ve essentially created ‘negative emissions plant’ — a plant that turns ambient CO2 into stone switches.

Iceland’s large basaltic fields could be a boon for CCS. Image via Unsplash.

The key to rapid mineralization of carbon is basalt – a volcanic rock which Iceland has an abundance of. Iceland is actually mostly made up of basalt (90%), and within basalt, CO2 can quickly mineralize (morph into carbonate rocks). “The potential of scaling-up our technology in combination with CO2 storage, is enormous,” said Christoph Gebald, the founder and CEO of Climeworks, the company behind the technology.

But for all these exciting developments, there’s one part we’ve purposely left out until now: money.

Without a carbon tax, CCS just won’t work

What about the money? As we’ve seen in the case of renewable energy, green technologies can only truly succeed when they have at least some economic advantage. Separating CO₂ from other chemicals is costly and also requires energy. But unlike renewable energy, in the case of CCS, there’s no real economic advantage — all you have is a method of reducing CO₂ emissions, that’s it.

At the moment, even as CCS is making great strides in terms of technology and research, the funding for said technologies is starting to shrink. This is a problem not just for carbon storage, but for our ability to meet current climate commitments and avoid catastrophic environmental and economic damage.

Nowadays, CCS projects rely on government incentives and standards — even though economists generally agree that these programs are less effective and more costly than a carbon price. Carbon pricing is notoriously unpopular and hotly debated, but increasingly, leading economists are calling for some sort of a climate tax. Without such a tax (or some pricing mechanism), CCS remains a niche technology and is unlikely to scale massively into the future.

“I prefer to have an economy-wide carbon price to create markets for low-carbon technology. Then markets, not advocates, will make decisions about the technology mix. I believe deployment of CCS would be significant under such a policy,” writes Howard J. Herzog Senior Research Engineer, Massachusetts Institute of Technology.

Simply put, new policies are dearly needed to incentivize commercial CCS. No matter how you look at things reaching net-zero emissions (and maybe, someday even negative emissions) seems much harder without CCS — but without financial incentives CCS cannot flourish, even when the technology matures. A University of Warwick report concludes:

“CCS has considerable potential to reduce CO2 emissions not only by a significant amount but also at a social cost that most economists would not consider prohibitive, particularly in comparison to the social costs predicted for a business-as-usual scenario with unregulated carbon emissions.”

“Clean coal is a lie,” coal CEO admits

Robert Murray, CEO of Murray Energy Corp., the largest coal company in the US, has long tried to convince people that global warming is a hoax. But even he admits that the so-called “clean coal technologies” are a load of nothing — a lie.

Coalers against coal

“Carbon capture and sequestration does not work. It’s a pseudonym for ‘no coal,’” the CEO of Murray Energy, the country’s largest privately held coal-mining company, told E&E News.

Clean coal? No such thing. Image via Pixabay.

Carbon capture and storage (CCS), the proposed technique, involves trapping the carbon from burning coal and then storing it permanently, usually underground. This is a challenging task, both technologically, and financially. In a world where natural gas is often cheaper than coal and where renewables are becoming more and more affordable, coal is struggling to keep up in any form. There’s a lot of concern about the scientific and economic possibility of CCS, even ignoring environmental concerns. So CCS, often referred to as “clean coal,” seems expensive, ineffective, and an overall counterproductive option.

Still, CCS has been touted as a magic solution for the natural fall of the coal industry, which is why it’s so unexpected to see someone like Murray speak against it so bluntly. Murray went on record saying that ‘clean coal’ just doesn’t do anything.

“It is neither practical nor economic, carbon capture and sequestration,” he said last week. “It is just cover for the politicians, both Republicans and Democrats that say, ‘Look what I did for coal,’ knowing all the time that it doesn’t help coal at all.”

The cat is out of the bag, but really, the news here isn’t that clean coal doesn’t do anything — it’s that big execs are admitting it.

Clean coal doesn’t exist

You got that right buddy. Image credits: linh.m.do / Flickr.

This is not a new type of statement. Environmentalists such as Dan Becker, director of the Sierra Club’s Global Warming and Energy Program, have often claimed that the term “clean coal” is misleading: “There is no such thing as clean coal and there never will be. It’s an oxymoron,” he said. He’s not the only one to hold that view.

“There is no such thing as ‘clean coal,’” Travis Nichols, a spokesman for the environmental giant Greenpeace, told The Huffington Post by email. “It’s a myth used by the industry to get taxpayer money in order to prop up a dying industry. It’s worse than pixie dust and hope, it’s coal dust and nope. Coal miners deserve a just transition, not snake oil and empty promises.”

Even other coal industry CEOs publically admit ‘clean coal’ is all hype. In an interview with ABC, Martin Moore, who is the CEO of CS Energy, one of the biggest energy company Australia, said new generation coal plants use less coal for the same amount of energy and “can have about 25 per cent less emissions”. But even him wasn’t impressed by ultra-super-critical plants.

“It’s not game-changing. You’ve still got to think that ultra-super-critical produces twice the emissions of gas-fired technology,” he said.

The science backs it up. Clean coal is indeed an oxymoron and its technological potential has yet to be demonstrated. CCS consumes a lot of energy (25% more), while producing the same yield. But that isn’t even the difficult part. You have to carry millions and millions of tons of high-pressure CO2, safely store them somewhere, using an infrastructure that doesn’t exist. Again, you have to do all this while competing with natural gas and renewables which are already cheaper than coal. It’s just a big no-no, on all fronts.

So if doesn’t make scientific sense, it doesn’t make economic sense, and even coal people are against it — why does President Trump insist on fighting this losing battle?

“My administration is putting an end to the war on coal,” Trump said. “We’re going to have clean coal, really clean coal.”

We don’t really know for sure, but as it’s been so often the case, the President is lying. “Really clean coal” simply doesn’t exist. Just look at this statement from the Office of Fossil Energy, explaining the state of CCS technology:

“Today’s capture technologies are not cost-effective when considered in the context of storing CO2 from existing power plants. DOE/NETL analyses suggest that today’s commercially available post-combustion capture technologies may increase the cost of electricity for a new pulverized coal plant by up to 80 percent and result in a 20 to 30 percent decrease in efficiency due to parasitic energy requirements. Additionally, many of today’s commercially available post-combustion capture technologies have not been demonstrated at scales large enough for power-plant applications.”

Sure, there are several small CCS experiments scattered across the world, but in the US at least, a working CCS carbon plant just doesn’t exist.

So instead of diverting efforts and resources into a technology that can’t work, why not focus on something that is already working?

The Semail (or Samail) ophiolite landscape as seen in a 2012 NASA satellite image. Credit: NASA.

Could Oman’s mountains hold the key to reversing climate change?

Deep inside the jagged red mountains of Oman, visitors with a trained eye might be shocked by an amazing sight: the world’s only exposed sections of the Earth’s mantle. Scientists are now sampling cores from this region to find out how a spontaneous process turned CO2 into limestone and marble millions of years ago. The answers they might unravel could one day offer a cheap and efficient solution for removing CO2 from the atmosphere and oceans.

The Semail (or Samail) ophiolite landscape as seen in a 2012 NASA satellite image. Credit: NASA.

The Semail (or Samail) ophiolite landscape as seen in a 2012 NASA satellite image. Credit: NASA.

Capturing carbon

The average American needs around 980 trees to offset their carbon footprint. Massive reforestation, especially in those hard struck parts of the world, must be a top priority in any policy meant to tackle climate change. But the truth is after you add the numbers, trees aren’t enough. We’re simply releasing more carbon from beneath the ground in the form of fossil fuels than any large forest can absorb. This is why many scientists are so interested in carbon capture and storage (CCS) technologies.

One of the most promising CCS projects I’ve come across is the Hellisheidi geothermal plant in Iceland. Here, carbon dioxide is dissolved in water and injected into the ground where it interacts with the surrounding rock and becomes mineralized. The whole process is 95 to 98 percent efficient and CO2 can basically turn into a rock in just two years.

Elsewhere, in China, the Sinopec fertilizer plant filters carbon and reuses it as fuel. According to the International Energy Agency, overall some 27 million tons of carbon are currently captured and stored across the world by 16 projects. An impressive start but in the grand scheme of things, that’s barely a dent (0.1%) in the 40 billion tons or so that human activity emits yearly.

“Any one technique is not guaranteed to succeed,” said Stuart Haszeldine, a geology professor at the University of Edinburgh who serves on a U.N. climate body studying how to reduce atmospheric carbon, for the Associated Press. “If we’re interested as a species, we’ve got to try a lot harder and do a lot more and a lot of different actions,” he said.

Naked Earth and its submerged mountains

One unique pathway for mitigating carbon in the atmosphere might be hiding in plain sights, in the rock formations of the al-Hajjar Mountains of Oman. The rugged mountains stand at their highest at 2,500 meters (8,200 feet) above sea level. Millions of years ago, some parts of these mountains were below the sea level. Many rocks used to lie in Earth’s interior, at the boundary between crust and mantle, but when the ancient Tethys Ocean narrowed and closed, the squeezing force thrust the ancient sea floor upward. This sort of landform is known to geologists as ophiolite, a term that describes oceanic crust that now sits at the land surface.

“You can walk down these beautiful canyons and basically descend 20 kilometers (12 miles) into the earth’s interior,” said in a statement Peter Kelemen, a geochemist at Columbia University’s Lamont-Doherty Earth Observatory, who has been exploring Oman’s hills for nearly three decades.

There are various rocks that comprise the ophiolite sequence. Along the boundary with the base of the crust, you can find chromite which the sultanate mines. Elsewhere, some layers of rocks (the first in the crust, rather than the mantle) are composed of gabbro. But what interests climate scientists is the peridotite, a rock that was once part of Earth’s mantle and reacts with the carbon in air and water to form marble and limestone.

It’s believed a billion tons of CO2 is trapped in the peridotites of al-Hajjar Mountains. When rain pulls carbon from the exposed mantle,  stalactites and stalagmites form in the mountain caves.

In order to understand how all of this process works, Kelemen and 40 other scientists have formed the Oman Drilling Project. So far, $3.5 million in funding has been pledged by organizations around the world, among which NASA.

So far, the team has dug up dozens of core samples from four different sites in Oman’s mantle-exposed mountains. Some 13 tons of core samples will be shipped to the Chikyu, a research vessel off the coast of Japan where geologists will work round-the-clock shifts to better understand the chemical process that traps the carbon in rock. They’ll also be interested in finding ways to speed up the process given all that carbon has accumulated over 90 million years and time is not really on our side. In only 150 years, average CO2 levels in the atmosphere have soared from 280 to 405 parts per million.

“Just like in Oman’s mountains, the submerged rock would chemically absorb carbon from the water. The water could then be cycled back to the surface to absorb more carbon dioxide from the atmosphere. However, that would be following years of rigorous testing, but hopefully this project, and this discovery retains support,” Kelemen told the Oman Times.

Late 2015, 196 nations signed and later ratified the Paris Agreement — an international pact where each signatory pledges to cap or reduce its carbon emissions such that collectively we might steer away from any pathway that leads to more than 2 degrees C of warming. The elections in the United States have side tracked a bit this landmarked agreement, though officially all the other signatories besides the United States have vowed to stay steadfast and deliver on their pledges.

According to some estimates, however, the planet is already locked into 1.5 degrees C of warming. Renewable energy and energy efficiency measures, coupled with the scrapping of coal, oil, and gas, are paramount if we want to avoid catastrophic runaway global warming. But seeing how CO2 can stay in the atmosphere for up to two centuries, these measures have to be joined by CCS. With every passing day, CCS becomes more and more important. Hopefully, al-Hajjar’s secrets might help save us and the countless other species we share this planet with.


Scientists are trapping more and more CO2 into volcanic basalt

As we previously reported, researchers have been testing a method of underground CO2 storage: injecting it into basaltic rock. Now, building on that work, undiluted CO2 was stored and in a much higher quantity: 1,000 tonnes of fluid carbon dioxide were safely stored in underground basalts in Washington.

That’s trapped CO2. Image credits: PNNL.

Even in the most optimistic scenarios, we can’t completely eliminate all our greenhouse gas emissions. So if we want to become carbon-neutral or as close to it as possible, we’re going to need some ways of developing more “negative emissions”. Negative emissions are, as the name puts it, a way of retracting emissions from the atmosphere. Forests and kelp beds are often regarded as ways to reduce emissions, but they are only carbon sinks – they take existing carbon from the atmosphere and move it in the biosphere, a process which can be reversed by cutting trees or wildfires for example. Not to say that reforestation isn’t going to play a key role – because it is – but it’s technically not a negative emission.

Instead, researchers were thinking about something else: injecting carbon dioxide into the underground. Carbon Capture and Storage (CCS) is a field of science where CO2 is extracted from the atmosphere and stored underground. Geologists have mostly focused on existing voids, such as former oil fields, but that’s tricky because the fields are susceptible to leakage. So instead, they’re now turning to mineralizations – turning CO2 into minerals. Until now, this process was thought of as unpractical because it takes too long to solidify the CO2, but researchers from Columbia University, University of Iceland, University of Toulouse and Reykjavik Energy have found a way to make it work in recent years.

But while they first dissolved CO2 in water and injected it into a basalt formation, this new effort stored undiluted CO2. A team from the US Department of Energy’s Pacific Northwest National Laboratory (PNNL) had already shown that the chemical reactions could happen in lab conditions so they set out to test it in the field.

“Now we know that this mineral trapping process can occur very quickly, it makes it safe to store CO2 in these formations,” says researcher Pete McGrail. “We have been conducting laboratory tests on basalts from the region for several years that have conclusively demonstrated the unique geochemical nature of basalts to quickly react with CO2 and form carbonate minerals or solid rock, the safest and most permanent form for storage in the subsurface,” he added. “We know now that in a short period of time the CO2 will be permanently trapped.”

While previous efforts took place in Iceland, this time, they injected the fluid carbon dioxide into hardened lava flows some 900 meters (2,952 feet) underground, near the town of Wallula in Washington State. At that depth, basalt formations are rich in calcium, iron, and magnesium. When the CO2 is injected, these elements become unstable and then dissolve, forming ankerite, a carbonate material similar in some regards to limestone.

Their experiment was a definite success, and the carbon was bound to the basalt, never to escape again.

“[The CO2] can’t leak, there’s no place for it to go, it’s back to solid rock,” explains McGrail. “There isn’t a more safer or permanent storage mechanism.”

However, scaling this technique still remains problematic. Carbon storage is also expensive, and it’s unclear at this point how attempts to scale it up will affect its overall costs. The good thing is that basalt formations are plentiful around the world, but it’s also not clear just how big the absorptive capacity of the basalt really is. Global carbon emissions from fossil fuel use alone were 9.795 gigatonnes in 2014 and we’ve yet to understand just how much of that the basalts can suck up. So let’s not get overly excited just yet. It’s a promising technique and one that can definitely make a difference for global emissions, but we’re still miles away from actually make it work on a large scale. Let’s all head to the ‘cautiously optimistic’ room for now.

The findings are published in Environmental Science & Technology Letters