- While trees and other plants can remove some carbon dioxide from the atmosphere, most climate change experts agree we can't plant enough, fast enough, to do the job alone.
- Carbon capture technology has been around for decades, and is used to strip carbon out of factory emissions as well as remove carbon that's already in the air.
- But it's expensive, and until the cost of releasing carbon into the air rises, there's little economic incentive to use it.
Elon Musk is going to pay $100 million towards a prize to come up with the best carbon capture technology. (Or so he tweets. Details are scarce so far.)
The maverick tech CEO's promise is not particularly notable for its generosity. With a net worth of over $200 billion, $100 million is 0.05% of Musk's wealth.
But still, the richest person in the world's tweet brings attention to an often-overlooked technology that has been around since the 1970s but has mostly been relegated to niche corners of the energy community.
"Mr. Musk's announcement reflects a maturation in the private sector around climate change and investment," Julio Friedmann, a senior research scholar at the Center on Global Energy Policy at Columbia University, tells CNBC via email. "As in the past, Mr. Musk's announcement has shaken up the gumball machine."
Why not just plant more trees?
One popular reaction to Musk's tweet was that he would be better to spend his money planting trees. Trees, like other plants, consume carbon dioxide in the process of photosynthesis and release oxygen. There is an international initiative, 1t.org, which aims to restore and grow one trillion trees by 2030 to mitigate climate change. The trillion trees campaign is run by the World Economic Forum and funded by the Marc R. Benioff Foundation, an eponymous philanthropic effort funded by the billionaire Salesforce CEO.
But even 1t.org knows planting trees is not a silver bullet.
"Addressing climate change will require investment in technologies that help to limit future emissions, such as electric vehicles, and also the drawdown of carbon from the atmosphere. Nature-based solutions can help with both of these, but we will need thousands of solutions in combination," says Tom Crowther, a tenure-track professor of Global Ecosystem Ecology at ETH Zürich and the chief scientific advisor to the United Nation's Trillion Tree Campaign. "There is huge potential for direct carbon capture technology as part of a diverse climate plan," Crowther tells CNBC from Switzerland via email.
So does Musk. In response to one tweet recommending tree-planting, Musk said trees "are part of the solution, but require lots of fresh water & land. We may need something that's ultra-large-scale industrial in 10 to 20 years."
In that vein, here's a look at where carbon capture, utilization and storage or sequestration (CCUS), which is often shortened to "carbon capture," technology stands now and why it has, thus far, not been more broadly deployed.
Carbon capture from factory emissions: Where it stands
There are currently 21 large-scale CCUS commercial projects around the globe where carbon dioxide is taken out of factory emissions, according to the International Energy Agency, a Paris-based intergovernmental energy organization. The first one was set up in 1972.
The earliest CCUS technology was used for enhanced oil recovery, meaning the carbon dioxide is pumped into an oil field to help oil companies retrieve more oil from the ground, Howard Herzog, a senior research engineer at the MIT Energy Initiative and author of the book "Carbon Capture," tells CNBC.
It wasn't until the 1980s that carbon capture technology was studied for climate mitigation efforts, but even then, it was "mainly lone wolves," Herzog says. By the 1990s, "activity really ramped up," he says.
One example in the United States is in Decatur, Ill., where the food processing giant Archer Daniels Midland Company launched a carbon capture and storage project in 2017. It has the capacity to take 1.1 million tons of carbon per year out of the emissions released by a corn processing factory, and stores that carbon a mile and a half underground.
For factory carbon-capture, emissions are routed through a vessel with a liquid solvent which essentially absorbs the carbon dioxide. From there, the solvent has to be heated up in a second tower — called a "stripper" or "regenerator" — to remove the CO2, where it's then routed for underground storage. The solvent can then be re-used in the first vessel or tower, Herzog says.
If the storing is done carefully, "you should be okay," Herzog says. "We don't have experience on the scale we want to go to," Herzog says, "but we've demonstrated you could do it correctly."
The U.S. Department of Energy is on the case, "developing models that simulate the flow of stored carbon dioxide, to help understand and predict chemical changes and effects of increased pressure that may occur."
Carbon capture from the air: Where it stands
In terms of reversing global climate change, there's already been too much carbon released into the atmosphere for us not to try and capture carbon and store it, says Klaus Lackner, the director of Center for Negative Carbon Emissions and professor at Arizona State University.
"The question of whether you want to store or not to store [carbon] was a very good question in 1980," Lackner tells CNBC. "But you needed to have this discussion 30, 40 years ago because back then you still had a chance to stop the train before we collide with something."
The concentration of carbon dioxide in the atmosphere is tracked as in parts per million, or PPM. As of December, atmospheric carbon dioxide stands at 414.02 ppm, according to the National Oceanic and Atmospheric Administration.
"We started the industrial revolution with 280 parts per million in the atmosphere," Lackner tells CNBC. "By now we have 415 [ppm], and we are going up 2.5 ppm a year at this moment." The consequences of that rising carbon dioxide in the atmosphere are already dire and will get worse. "The oceans have started to rise, hurricanes have gotten way worse, climate has become more extreme, and this will only get worse over the next decade," Lackner says.
The only choice, Lackner says, is to "draw down" the atmospheric carbon dioxide — or to suffer unknown, devastating consequences.
Capturing carbon from the air, not from a factory smokestack, is called "direct air capture," and there are currently 15 direct air capture plants in Europe, the United States and Canada, according to the IEA. "Carbon removal is expected to play a key role in the transition to a net-zero energy system," the IEA says, but currently it is a very expensive technology.
Direct air capture is "very expensive because the CO2 in the atmosphere is only .04%," Herzog tells CNBC, and the technical process of removing carbon dioxide from a gas gets more expensive the lower the concentration of the carbon dioxide gets. "But it is very seductive. A lot of people jumped on this," he says.
Lackner sees it as a necessity. "In the end, I see CO2 as a waste management problem. We have for two centuries simply dumped the waste from energy production — which is carbon dioxide — in the atmosphere and not thought about it any further, and we are gradually waking up to the fact that that's not acceptable," Lackner says.
The future of carbon capture technology
The technology exists to capture carbon and there is a grave need for climate change to be mitigated. So why isn't it being used everywhere already?
The problem is economics, says Herzog. "It's cheaper to put [carbon dioxide] in the atmosphere. It is cheaper to let it go up the smokestack than put this chemical plant on the back of the smokestack to remove it," Herzog says. "Who is going to pay for that?"
To change that reality, there must be economic costs to releasing carbon dioxide pollution into the atmosphere.
"The best capture technology will reduce these costs, but it will never be zero. Hence, even the best carbon capture technology will be useless if the world is not willing to put a price on carbon," Berend Smit, a Professor of Chemical and Biomolecular Engineering at the Department of Chemical and Biomolecular Engineering, at the University of California, Berkeley, tells CNBC by email. His research focuses on finding the optimal material for carbon capture.
In the meantime, scientists and researchers are working to make current carbon capture technologies better.
"Over the past 10 years, there are a number of innovations and improvements to enable us to save more energy and cost up to 70% less for new carbon capture processes," Paitoon (P.T.) Tontiwachwuthikul, a professor of industrial and process systems engineering at the Canadian Academy of Engineering and a co-founder of the Clean Energy Technologies Research Institute University of Regina, tells CNBC by email. "These include novel solvents (and their mixtures) as well as new process hardware items (e.g. new columns, catalysts, etc.)."
Smit is also working on how to use a kind of sponge "with a strong affinity for carbon dioxide," he says. "Hence if we flow air through the sponge, the CO2 gets removed. Once the material is saturated with CO2, we need to heat it, pure CO2 comes out, which we can then store. The sponge is empty and we can start over again."
Lackner has developed a free-standing device to take carbon dioxide out of the air. "Everybody's a machine out there right now, they are sucking carbon dioxide or pushing carbon dioxide with fans and blowers ... we think that the wind alone is good enough to move the air around and our design aims to just be passively standing in the wind, just like a tree." While the technology has been demonstrated on campus, it's still in its infancy.
Fundamentally, it all comes down to money. "You need regulatory frameworks where basically if you want to dig up carbon, you better show that you put an equal amount away," Lackner says. "If you have a cheaper way by all means do it first. if you don't have a cheaper way, you have no excuse because this one will work."