Will negative emission technologies save the planet?
Climate physicist Cyril Brunner explains how negative emission technologies can help us fighting climate change.
Credits to Walter Newton
A few weeks ago, I had the pleasure to enjoy a blonde beer and an interesting conversation with Cyril Brunner. He is a postdoctoral researcher in Climate Physics at ETH in Zurich and his research focuses on assessing the potential of carbon dioxide removal for Switzerland.
This includes all carbon sequestration methods, like improved forest management, biochar, soil carbon sequestration, enhanced weathering, direct air capture and storage, or bioenergy carbon capture and storage. Our exchange was so inspiring that I needed to share it with Caldo’s friends.
Cyril, what do negative emission technologies do and why do we need them?
Negative emissions technologies are means to remove carbon dioxide (CO2) from our atmosphere. The CO2 removal can be done through a human-engineered capture process, like direct air capture and storage (DACS), or the enhancement of a biological process, like reforestation. The result is the same: CO2 is removed from the atmosphere and temporarily stored in the biosphere or permanently stored in the geosphere.
The reason why we need them is fairly simple. Imagine the Earth’s atmosphere is like a bathtub filling up with greenhouse gasses. The fuller it becomes, the more we feel the effects of climate change. We need to turn off all the taps as soon as possible by reducing emissions across the economy.
However, fully closing all taps is very difficult; thus, there will still be hard to avoid emissions that continue to fill the bathtub. By unplugging the outlet, we can balance this, potentially even lower the level of greenhouse gases in the bathtub. This is exactly what negative emission technologies do. You see, without carbon dioxide removal, there is no net-zero, and without net-zero, global warming will continue.
To meet the Paris Agreement goals, we will need to remove globally 10 gigatons of carbon dioxide per year through 2050, and 20 gigatons per year from 2050 to 2100. Despite the covid pandemic in 2020, we have emitted about 31 gigatons of carbon dioxide in 2020 alone. This means the industry that we need to build to remove CO2 has to be very big. This is a huge ask!
On September 8, Climeworks – a pioneer in DACS technologies – began the operations of Orca, the world’s largest direct air capture and storage plant. It has a capturing capacity of 4,000 tons of CO2 per year, which is as little as the annual emissions from about 790 cars! Although Climeworks plans to scale its capturing capacity by a factor of ten in the next three years, I am concerned about the actual limits to large-scale deployment of these technologies.
Imagine we are in 2050. Do you envision a world where DAC collectors are placed on top of our buildings, similar to solar panels, sucking up billions of tons of CO2?
Indeed, the new plant of Climeworks is tiny compared to what we have to do. However, it is easier to optimize the process when working on a smaller plant. This is because larger plants are likely to be built with the same single collectors as the 48 collectors used in Orca.
It is like testing 20 solar panels on a small area, say 5 x 10 m. When you scale this into a large power plant, you will use the same single units of solar panels, just many more of them. History has shown that humans are quite good at making many of the same little things!
Regarding your vision in 2050, I very much like it, because it means we achieved a lot. For example, it implies that we will perceive the emission of a tonne of greenhouse gases as a form of waste that we need to clean up. But I don’t think we will see many of these collectors in cities, as there are mainly three requirements for locations of such direct air capture and storage facilities.
You need a large, so far unused potential for renewable power, as these machines are quite thirsty for energy.
You ideally want to capture the CO2 close to where you can permanently store it.
You need space for it.
Based on these requirements, a city is not a good fit. So, these facilities are much more likely to be installed somewhere like Iceland or Oman. After all, from a climate point of view, it does not matter where we capture the CO2 on the globe. I also would like to stress that there are many other options to realize negative emissions other than direct air capture and storage.
And what would be the best one?
I do not think there is a silver bullet solution. Let me give you an example: what is your favorite dish? Does it mean that you should only eat this single dish for the rest of your life? This would not be healthy or fun. So diversifying is key. The same goes for negative emissions.
Every approach has its advantages and disadvantages. As you use more and more of them, some aspects shift from being advantageous to having adverse side effects. Thus, the ultimate solution will be one where we use a bit of everything, but nothing too excessive!
On top of scaling capabilities, DACS is very expensive. Removing one ton of CO2 with Climeworks’ solutions costs 600 USD for bulk requests, and as high as 1,200 USD for eco-friendly individuals. This is not affordable for the majority of us. Do you think prices will decrease in the future?
It is true that the technology is very expensive today. Jan Wurzbacher, a co-founder of Climeworks, said that the company aims to get the cost down to 200-300 USD a ton by 2030 and to 100-200 USD by the middle of the next decade. Such prices are much more “democratic” than what we have today.
We should also consider that there are more market players but Climeworks. For example, a group of researchers at MIT has designed a new approach to carbon capture. They estimate a cost of 30-50 USD per ton of CO2 captured. Such a price makes the solution affordable to a wider public, and so triggers an economic opportunity. This gives me hope: if tackling climate change becomes a business case - a case where one can make a lot of money - we will quickly get on track to solve this crisis.
Good point! But even if we will fix the technology’s scaling and pricing issues, some ethical concerns remain. For example, CarbFix has developed a solution to inject CO2 in liquid form into porous basaltic rock underground. The liquefied carbon dioxide reacts with the rock to form calcite and so avoid any risk of leakage. Iceland is rich in basaltic rocks and the CO2 storage capacity is huge. Does it mean we are building an immense underground landfill?
Well, it depends if you call fossil oil and gas fields a “landfill”, too. In essence, we extract(ed) fossil fuels from deep geological storage, often in porous rock formations. If we put the carbon part of the fossil fuels back to these very deep geological porous rock formations, I would not see this as a landfill.
In addition, if you inject the CO2 into mineralizing rock formations like Carbfix or 44.01 are doing, then you indeed form minerals. They are by far the most extensive stock of carbon on earth – 99.94 % of all carbon is found in the lithosphere, so within minerals. We would simply speed up the natural process of how CO2 is removed from the atmosphere on geological timescales. This is also how the carbonates of entire mountain ranges, like the Dolomites, were formed.
I know you are a scientist, but don’t you think DACS technologies are a dangerous distraction for politicians? It is like magic: you can keep going with your business as usual and theoretically not harm the planet.
Very true. This is a moral hazard, and it is vigorously discussed among decision-makers and scientists. For me, two things are important to note.
We have to understand that the use of negative emissions is not up to debate. To stabilize global warming, we need to reach net-zero. This holds for every temperature target, be it 1.5°C, 2°C, or even 5°C. Because we will always emit some greenhouse gases, we will always need to balance them to achieve net-zero. For this, we require negative emissions.
The more negative emissions we use, the harder it will become to remove an additional tonne of CO2. Simply because we opt first for the low-hanging fruits and go to the next best option as soon as we exhausted the capacity of the first option.
That means there is a tendency for negative emissions to become increasingly expensive the more we use them. Already nowadays, the low-carbon solution is often cheaper than the traditional approach. Consequently, adding the cost from negative emissions will make the traditional approaches even less competitive.
However, it is crucial that the emitters come up with the costs of negative emissions at the same time as they emit. Not a couple of years later. Otherwise, it would not work as people would often bet on negative emissions, which will be less expensive in the future than what they are today.
All in all, our primary focus must remain on substantially lowering our emissions. We know how to do this. Negative emissions should come after that, remaining a crucial addition to balancing the truly hard-to-avoid emissions.
