All you need to know about Elon Musk’s Carbon Capture Prize

[This is a transcript of the video embedded below.]


Elon Musk has announced he is sponsoring a competition for the best carbon removal ideas with a fifty million dollar prize for the winner. The competition will open on April twenty-second, twenty-twenty-one. In this video, I will tell you all you need to know about carbon capture to get your brain going, and put you on the way for the fifty million dollar prize.

During the formation of our planet, large amounts of carbon dioxide were stored in the ground, and ended up in coal and oil. By burning these fossil fuels, we have released a lot of that old carbon dioxide really suddenly. It accumulates in the atmosphere and prevents our planet from giving off heat the way it used to. As a consequence, the climate changes, and it changes rapidly.

The best course of action would have been to not pump that much carbon dioxide into the atmosphere to begin with, but at this point reducing future emissions alone might no longer be the best way to proceed. We might have to find ways to actually get carbon dioxide back out of the air. Getting this done is what Elon Musk’s competition is all about.

The problem is, once carbon dioxide is in the atmosphere it stays there for a long time. By natural processes alone, it would take several thousand years for atmospheric carbon dioxide levels to return to pre-industrial. And the climate reacts slowly to the sudden increase in carbon dioxide, so we haven’t yet seen the full impact of what we have done already. For example, there’s a lot of water on our planet, and warming up this water takes time.

So, even if we were to entirely stop carbon dioxide emissions today, the climate would continue to change for at least several more decades, if not centuries. It’s like you elected someone out of office, and now they’re really pissed off, but they’ve got six weeks left on the job and nothing you can do about that.

Globally, we are presently emitting about forty billion tons of carbon dioxide per year. According to the Intergovernmental Panel on Climate Change, we’d have to get down to twenty billion tons per year to limit warming to one point five degrees Celsius compared to preindustrial levels. These one point five degrees are what’s called the “Paris target.” This means, if we continue emitting at the same level as today, we’ll have to remove twenty billion tons carbon dioxide per year.

But to score in Musk’s competition, you don’t need a plan to remove the full twenty billion tons per year. You merely need “A working carbon removal prototype that can be rigorously validated” that is “capable of removing at least 1 ton per day” and the carbon “should stay locked up for at least one hundred years.” But other than that, pretty much everything goes. According to the website, the “main metric for the competition is cost per ton”.

So, which options do we have to remove carbon dioxide and how much do they cost?

The obvious thing to try is enhancing natural processes which remove carbon dioxide from the atmosphere. You can do that for example by planting trees because trees take up carbon dioxide as they grow. They are what’s called a natural “carbon sink”. This carbon is released again if the trees die and rot, or are burned, so planting trees alone isn’t enough, we’d have to permanently increase their numbers.

By how much? Depends somewhat on the type of forest, but to get rid of the twenty billion tons per year, we’d have to plant about ten million square kilometers of new forests. That’s about the area of the United States and more than the entire remaining Amazon rainforest.

Planting so many trees seems a bit impractical. And it isn’t cheap either. The cost is about 100 US dollars per ton of carbon dioxide. So, to get rid of the 20 billion tons excess carbon dioxide, that would be a few trillion dollars per year. Trees are clearly part of the solution, but we need to do more than that. And stop burning the rain forest wouldn’t hurt either.

Humans by the way are also a natural carbon sink because we’re eighteen percent carbon. Unfortunately, burying or burning dead people returns that carbon into the environment. Indeed, a single cremation releases about two-hundred-fifty kilograms of carbon dioxide, which could be avoided, for example, by dumping dead people in the deep sea where they won’t rot. So, if we were to do sea burials instead of cremations, that would save up to a million tons carbon dioxide per year. Not a terrible lot. And probably quite expensive. Yeah, I’m not the person to win that prize.

But there’s a more efficient way that oceans could help removing carbon. If one stimulates the growth of algae, these will take up carbon. When the algae die, they sink to the bottom of the ocean, where the carbon could remain, in principle, for millions of years. This is called “ocean fertilization”.

It’s a good idea in theory, but in practice it’s presently unclear how efficient it is. There’s no good data for how many of the algae sink and how many of them get eaten, in which case the carbon might be released, and no one knows what else such fertilization might do to the oceans. So, a lot of research remains to be done here. It’s also unclear how much it would cost. Estimates range from two to four hundred fifty US dollars per ton of carbon dioxide.

Besides enhancing natural carbon sinks, there are a variety of technologies for removing carbon permanently.

For example, if one burns agricultural waste or wood in the absence of oxygen, this will not release all the carbon dioxide but produce a substance called biochar. The biochar keeps about half of the carbon, and not only is it is stable for thousands of years, it can also improve the quality of soil.

The major problem with this idea is that there’s only so much agricultural waste to burn. Still, by some optimistic estimates one could remove up to one point eight billion tons carbon dioxide per year this way. Cost estimates are between thirty and one hundred twenty US dollars per ton of carbon dioxide.

By the way, plastic is about eighty percent carbon. That’s because it’s mostly made of oil and natural gas. And since it isn’t biodegradable, it’ll safely store the carbon – as long as you don’t burn it. So, the Great Pacific garbage patch? That’s carbon storage. Not a particularly popular one though.

A more popular idea is enhanced weathering. For this, one artificially creates certain minerals that, when they come in contact with water, can bind carbon dioxide to them, thereby removing it from the air. The idea is to produce large amounts of these minerals, crush them, and distribute them over large areas of land.

The challenges for this method are: how do you produce large amounts of these minerals, and where do you find enough land to put it on. The supporters of the American weathering project Vesta claim that the cost would be about ten US dollars per ton of carbon dioxide. So that’s a factor ten less than planting trees.

Then there is direct air capture. The most common method for this is pushing air through filters which absorb carbon dioxide. Several petrol companies like Chevron, BHP, and Occidental currently explore this technology. The company Carbon Engineering, which is backed by Bill Gates, has a pilot plant in British Columbia that they want to scale up to commercial plants. They claim every such plant will be equivalent in carbon removal to 40 million trees, removing 1 million tons of carbon dioxide per year.

They estimate the cost between ninety-four and 232 US dollar per ton. That would mean between two to four trillion US dollars per year to eliminate the entire twenty billion tons carbon dioxide which we need to get rid of. That’s between two point five and five percent of the world’s GDP.

But, since carbon dioxide is taken up by the oceans, one can also try to get rid of it by extracting it from seawater. Indeed, the density of carbon dioxide in seawater is about one hundred twenty five times higher than it is in air. And once you’ve removed it, the water will take up new carbon dioxide from the air, so you can basically use the oceans to suck the carbon dioxide out of the atmosphere. That sounds really neat.

The current cost estimate for carbon extraction from seawater is about 50 dollars per ton, so that’s about half as much as carbon extraction from air. The major challenge for this idea is that the currently known methods for extracting carbon dioxide from water require heating the water to about seventy degrees Celsius which takes up a lot of energy. But maybe there are other, more energy efficient ways, to get carbon dioxide out of water? You might be the person to solve this problem.

Finally, there is carbon capture and storage, which means capturing carbon dioxide right where it’s produced and store it away before it’s released into the atmosphere.

About twenty-six commercial facilities already use this method, and a few dozen more are planned. In twenty-twenty, about forty million tons of carbon dioxide were captured by this method. The typical cost is between 50 and 100 US$ per ton of carbon dioxide, though in particularly lucky cases the cost may go down to about 15 dollars per ton. The major challenge here is that present technologies for carbon capture and storage require huge amounts of water.

As you can see an overall problem for these ideas is that they’re expensive. You can therefore score on Musk’s competition by making one of the existing technologies cheaper, or more efficient, or both, or maybe you have an entirely new idea to put forward. I wish you good luck!