Dangerously good CO2 vacuum cleaners: "Don't let us be fooled into believing that it works"

In just over 20 years, the EU wants to be climate-neutral.

Dangerously good CO2 vacuum cleaners: "Don't let us be fooled into believing that it works"

In just over 20 years, the EU wants to be climate-neutral. But that only works if we pull CO2 out of the atmosphere on a large scale, says Oliver Geden from the German Institute for International and Security Affairs (SWP). Because no matter how few greenhouse gases we emit, agriculture, aviation or industry will never be neutral. In the ntv "Climate Laboratory" the lead author of the sixth assessment report of the Intergovernmental Panel on Climate Change reports on several methods with which this is possible: ecosystem-based such as afforestation with limited potential; ocean-based with still unclear side effects; technological ones that are still very expensive. If we fully exploit all possibilities, we will make the fight against climate change much easier, says Oliver Geden. Nevertheless, he recommends limiting the use politically.

ntv: The EU wants to become climate neutral by 2045. You say that this is not possible without negative emissions, we have to remove CO2 from the atmosphere. Why?

Oliver Geden: Because at the time of climate neutrality or greenhouse gas neutrality, there are still emissions left. It's just a net zero goal. We will still have emissions from agriculture, aviation or industry. We have to balance that. For this we need CO2 removal. That is the goal of net zero emissions.

So it's out of the question for humans to live on earth without overstraining it?

There is no imaginable world without emissions. I get them when I keep animals, build a house, a road or a new railway line. But that's not a problem, you can compensate for it. But in order to limit the further increase in temperature, the neutrality requirement is important. However, if we miss the 1.5 degree target but intend to go back there, we need globally negative emissions and have to remove more CO2 from the atmosphere than we emit. For that we need net negative emissions.

Does this mean that climate neutrality and negative emissions are two different things?

Linguistically, that is actually not easy in German. The last IPCC report in which I oversaw this topic therefore makes this distinction between CO2 removal and negative emissions. CO2 removal, in English Carbon Dioxide Removal, describes methods such as reforestation to get CO2 out of the atmosphere again. The term negative emissions is used when the CO2 removal is greater than the CO2 emission or the emission of other greenhouse gases that we still have.

What options are there for getting CO2 out of the atmosphere again?

A broad spectrum. Usually they are classified into ecosystem-based methods like reforestation and other things that we already do today. There are also methods that we don't use, but have understood to a certain extent. For example, we can burn bioenergy, which can be trees, but also specially cultivated biomass, to use electricity and separate the CO2 and store it underground. That would also be a CO2 removal in itself. We can also use filter systems to cut CO2 directly from the ambient air and store it underground. This is what is known as Direct Air Capture. We still have very little understanding of methods by which certain substances could be added to the ocean to bind more CO2 there. This is relevant in that 70 percent of the earth's surface is covered with water.

So the spectrum ranges from methods that we know and use and that are also relatively cheap but possibly limited in their potential, to technological possibilities that are still very expensive, where there is a great need for research and where it can also be that there are unwanted side effects that we don't want to see.

But if we exploit all these possibilities, we would make the fight against climate change much easier, right?

Yes, but there are political and economic reasons why we should not prioritize these measures.

Which would be?

Suppose we realize CO2 removal and storage with Direct Air Capture at a very cheap price. Then you could get the misguided idea that we are simply building a second infrastructure with which we can pull out almost everything we emit and no longer make climate policy. Not only would that be insanely expensive, we also don't have the CO2 storage capacity for it. And we would ignore that there are other good reasons to do climate protection, including energy independence or air pollution. That means you have to define politically what percentage of our emissions we want to extract from the atmosphere with such methods.

It sounds like the biggest fear is that these methods might work too well?

Perhaps the greater danger is that before we actually know it, we convince ourselves that everything is working just fine, and as a result stop saving oil, gas and coal. I don't necessarily expect that in Germany or the EU, but if you look at the debates in the USA and other countries, you get the impression: Yes, that's the big technological solution!

I would say that we are more likely to achieve greenhouse gas or CO2 neutrality with 90 percent classical reduction and the remaining 10 percent with these methods of CO2 removal. Incidentally, in Germany and in the EU we are already achieving a relevant level of removal through afforestation and reforestation, which has not previously been counted towards the climate targets because it was considered dubious.

Are we talking about reforestation in Europe or in the Global South?

In Europe. Offsets or credits from climate projects in other countries could also be counted until 2020. But because, as I said, there were many dubious projects, the European and thus also German rules were changed in such a way that only what we achieve "at home" counts.

Who should take responsibility for removing these CO2 emissions again? How do you want to regulate that?

Nobody knows yet, but the debates are actually starting. Here's the thing: if we set a target of 1.5 degrees warming, you can convert that into a carbon budget that the world still has for greenhouse gas emissions. This so-called residual CO2 budget has almost been used up. Countries like India are also formulating net zero targets now, but of course much later than industrialized countries. It's a math that doesn't add up overall, so some countries need to be net negative earlier than others, namely the historical polluters like the US and Europe, to allow countries like India a longer period of transition. To my surprise, the US government's special envoy for climate protection, John Kerry, basically said yes immediately. Now there is a promise that the USA and Europe will clean up the "emission waste" at some point, but will continue to rely on coal, gas and oil for the time being. It's a bet on the future that I doubt will work out.

Is the commitment perhaps related to the fact that the USA is developing the corresponding machines and is hoping to be able to control the market for them in the long term?

That would be one possibility that American companies would want to secure the patents for such technologies. It's probably a similar story to that of wind and solar power: the production costs go down quickly, you can sell it all over the world and you don't have to change the local economy so quickly. This notion is actually widespread in the US, as are ocean-based solutions, where you add certain substances to the water to store CO2. Such debates are booming in the USA.

What kind of substances are we talking about?

There are two possibilities that are being discussed: I put certain nutrients, such as iron, in nutrient-poor ocean areas, for example in the South Pacific, and I basically contribute to the plankton bloom. This creates more biomass, which sinks. This was also attempted in Germany in 2009, shortly before the climate conference in Copenhagen, but caused a great deal of unrest.


It just didn't look particularly good that shortly before an important climate conference, experiments were being carried out that were being discussed under the label of geoengineering. As if you were already working on Plan B or C. But that is not discussed as much today, although British researchers have announced corresponding experiments for the Indian Ocean. This is often called ocean fertilization for the platton bloom. The second strand is ocean alkalinization: you bring in substances like ground mineral rock that bind CO2.

Some kind of miracle rock?

no There is also a natural process. If you see large boulders colored slightly green, that is also a mechanism of CO2 sequestration. A side effect of this in the ocean could be that acidification is also combated. So, the pH would change through this rock, but the question is what style of doing it. But that is a dream of the future and is severely restricted by international law.

And that's why CO2 removal with these machines?

Also. The advantage of this method is that you can easily measure the effect and determine whether the CO2 really stays underground. And geological storage in deep layers of rock have the advantage that they are considered to be very safe and very durable. That's the advantage over many of these ecosystem-based solutions: I know what I've achieved.

And how should one imagine these machines? It is always said that CO2 is sucked out of the air. Is that correct?

There aren't very many plants yet, and they are built in very different ways. But the biggest one is in Iceland at the moment and is in fact a mixture of a container and a vacuum cleaner. Basically it's a device that sucks in the ambient air because the CO2 content in it really isn't that high. Then it is chemically bound. If you heat this filter, you can then store it underground.

When you say that you can store it well underground for a long time: is that really a permanent solution? It sounds kind of dangerous when tons of CO2 are stored underground somewhere.

But that is already there, for example in the form of gas. In principle, I can also store CO2 wherever there are gas fields or gas storage facilities. Nevertheless, there are major reservations in Germany. This is often compared to nuclear repositories, which is really a skewed comparison. At the moment it looks as if we would rather transport our CO2 abroad, because there are countries that say: We have exploited gas fields, we'll be happy to take the CO2 off your hands. But for that we would need an infrastructure and would have to calculate: Is this transport chain even worthwhile from an economic point of view? Are there new emissions?

How would you transport the CO2?

Quite simply in pipelines.

There are a few left in Germany that we no longer need.

If you convert them, that would work. At the moment we are also talking a lot about these LNG terminals on the North Sea coast. A CO2 export terminal has already been included in the project planning for the terminal in Wilhelmshaven.

Does that mean you could reuse this infrastructure after the gas phase-out?

some. But even with a pipeline that is unsuitable, one would at least already have the route for a new one without having to redefine the route. But I can also transport CO2 by ship or truck.

Does the CO2 removal work? You mentioned the plant in Iceland, which went into operation last September.

Yes, it works. It wasn't the first system either, the process has been known for a long time. Iceland is all about streamlining the process. You have to imagine it as with early solar systems: the mechanism is understood, but it is still too expensive. Where can I save? With the material? In the processes of how to build these facilities?

What prices are we talking about right now?

They are in the range of 500 euros per tonne of CO2. That's a lot if you look at what emissions certificates cost in Germany. At the beginning of the year, a ton cost 30 euros, currently we are at 80 euros. When you have 100x or 10000x capacity at these facilities, no one can predict what price you'll end up at. But we know from solar and wind that it will drop significantly. Some are optimistic and consider 100 euros per tonne of CO2 to be realistic. Then we are not far from the price of the certificates and have arrived at the problem you raised: If the removal of CO2 from the air works at the same price as emissions trading, someone might suggest: Now we can continue without climate protection.

And buy petrol again.

I agree. That's why you have to regulate it politically and limit it to a certain level.

Clara Pfeffer and Christian Herrmann spoke to Oliver Geden. The conversation has been shortened and smoothed for better understanding.

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