Carbon removal — Part 2: fixing the roof despite a pay cut?
CO2 removal techniques will consume energy and can hardly be seen as directly productive. Unfortunately, we might also have to live with a constrained energy budget which will affect GDP growth. At the individual level, the closest analogy might well be a salary cut.
Without denying the tougher times ahead, we have to push for carbon removal. To spin the metaphor, despite a pay cut, we must fix the roof of the house to avoid catastrophic future damage.
Part 1: the CO2 genie is out of the bottle
Part 3: starting with the lowest-hanging fruits
For those who missed Part 1, we identified 3 priorities to tackle climate change:
- reduce carbon-based sources of electricity as much as possible by using renewable & nuclear energy and electrify as many processes as possible
- try to limit practices that will still depend on fossil fuel
- deploy CO2 removal technologies on a large scale
But what is CO2 removal then?
Preliminary note: The technical details will be discussed in following posts, here I only describe the different concepts.
We have to put back CO2 underground
CO2 removal techniques aim to permanently remove carbon atoms from the atmosphere into the largest natural storage location: underground.
Let’s start with the end of the process. Removing carbon involves injecting it in gaseous form into depleted oil or gas wells or into saline aquifers (porous cavities containing salt water). Then it’s about making sure that the gaseous CO2 does not escape to the surface, either by continuously checking for leaks or, ideally, by reacting it with various minerals so that it slowly turns back into limestone.
An alternative to geological storage is the transformation of CO2 into useful material and thus its temporary storage in another form. But we’ll talk about it a little bit later.
This CO2 will directly or indirectly be sourced from the atmosphere
Before this, we need to recover gaseous CO2. 2 techniques exist:
- Recovery from industrial or energy production processes (basically, a catalytic converter in the chimney of factories)
- Direct Air Capture: recovery directly from the atmosphere (a CO2 vacuum cleaner)
The concentration of CO2 in gases from industrial processes or energy production is much higher than in the atmosphere (several tens of percent versus 0.4%). This is because they are the products of the combustion of carbon-containing material. The capture of CO2 is therefore easier, and cheaper, in this case.
But there is an important caveat: the first process is carbon removal only if the burned material has previously absorbed carbon from the atmosphere. Recovering CO2 from the combustion of fossil material would simply prevent further transfer of carbon atoms from underground to the atmosphere.
The solution is therefore to burn biomass (trees, algae, organic waste, etc.) that has previously absorbed CO2 from the atmosphere through photosynthesis. In a sense, it is indirect air capture. This is called BECCS (BioEnergy Carbon Capture and Storage) and also allows, via combustion, to provide energy. It is the best known carbon removal technique, it could be profitable through the sale of this energy, and is therefore the most widely considered tool in the IPCC models.
There’s no silver bullet
However there are major drawbacks for BECCS: the biggest one being its land requirement. For it to work, we need a lot of biomass to grow and absorb CO2. Unfortunately, in order to reach the levels of carbon removal of the different 1.5 to 2 degrees models, we would have to dedicate to BECCS an area of between 300 and 700 million hectares, i.e. about the size of Australia (page 5 here). Similar biophysical limitations affect other potential methods (increased weathering or ocean fertilization).
As we saw, an alternative to geological storage is the transformation of CO2 into useful material and thus its temporary storage in another form. It’s called CCU: Carbon Capture and Utilization. The main applications are the processing of CO2 into fuels, chemicals and concrete building materials. The major advantage is that the sale of these products could generate income and thus make carbon capture profitable. But there are major drawbacks too:
- storage times are not relevant to the scale of climate change. Converting CO2 into fuel burnt by a car a few weeks later will only put the same carbon atoms back into circulation. This “just” reduces the number of carbon atoms that would have otherwise come from underground to run our economy, it is not to a net withdrawal from the atmosphere (except for concrete, which remains in this form for several decades)
- the potential uses of CO2 are unlikely to be large enough to store the CO2 quantities that have to be removed from the atmosphere (2.5 Gt CO2 removed annually thanks to the “conventional pathways”* in 2050 according to this litterature review while the needs will most likely be between 4 and 10 Gt, based on IPCC and IEA models)
*including EOR (Enhanced Oil Recovery), which I’ll discuss in a later post, but might arguably not be the best application for CO2 as the name suggests
Direct Air Capture will also be necessary on a large scale and will require a lot of energy
So what can we conclude?
- There’s no silver bullet and the situation requires a whole range of solutions: it is critical to develop CCU techniques to limit new underground carbon emissions AND BECCS & other complementary techniques for atmospheric carbon removal
- Inevitably, we will also need Direct Air Capture on a large scale
Let’s remember however that CCU and BECCS seem to be the only major technologies that can be profitable: CCU through the sale of carbon-based products, BECCS through energy production. The other techniques, on the contrary, consume energy.
The trillion-dollar Oil & Gas industry was created to extract underground carbon and emit it into the atmosphere to produce energy. We now have to build a “mirror” industry to return this carbon underground, this time without energy rewards so we can not expect, at least for a significant part, economic profitability.
On the contrary, the energy requirements for this will be massive
So what? It’s an effort but we’ve got plenty of energy so let’s do this anyway right?
Our energy budget will, at least temporarily, go down, impacting our GDP and our willingness to act
To get our energy, we invest some: we dig mines to get the coal we burn. The Energy Return On Investment (EROI) measures the ratio of energy obtained to energy invested. We have based our economy on fossil fuels, very high (>40) EROI energy sources adapted to many uses (electricity, transport…). But:
- Fossil fuels EROI is declining (-23% over the last 16 years) as they are increasingly difficult to reach
- Even though there still seem to be several decades of reserves left, the peak in the extraction of fossil fuels is very close
- Precisely because fossil fuels are becoming less competitive and less available, but also because we are putting in place welcome incentives for the climate, our economy will make a transition to greener electricity. The problem is that, on average, renewables currently have a lower (around 10) EROI than fossil fuels in their heyday
All of this, even without voluntarily seeking to reduce the uses still dependent on fossil fuels, will inevitably lead to a reduction in the amount of energy available to humans: an “energy cliff”.
On the other hand, GDP, as we calculate it, roughly measures the flow from natural resources to artificial ones (consumer goods). For this, we use energy. So when the amount of energy available to humans decreases, so does their ability to transform the world, and so does the GDP.
Indeed, energy productivity seems actually intimately linked to the growth of the economy as a whole. In other words, the decline in our energy budget might well lead to more frequent recessions. To re-use the analogy of an individual situation, here are the previously mentioned wage cuts.
Harder times are ahead. Of course, according to current economic logic, a process that consumes energy but produces nothing can not be profitable.
In this context, doing it anyway appears then like a double effort: it would mean, in times of slower growth, setting aside some of the energy at our disposal for a process that is intrinsically not directly beneficial to growth.
Okay, but we are changing our model, with carbon taxes for example. What about carbon removal in this new framework?
Even in new models, carbon removal is not productive
Let’s repeat: GDP, as we calculate it, roughly measures the flow from natural resources to artificial ones (consumer goods). For this, we use work and energy (derived from the same natural resources). We are now realizing the naivety of getting used to GDP growth levels that:
- depend on a temporary gigantic energy budget (since it was based on exhaustible very efficient fossil resources that were only initially easily accessible)
- and imply, through pollution and therefore climate change, dramatic consequences on the same resources and on the transformation assets from which is derived this very GDP (less fish to catch and more disasters affecting our factories for example)
We must include the “natural resources” variable in our economic logic to avoid doing the same mistake again. It seems we’re actually doing it bit by bit. But adding a constraint (a necessary one) to our model can only lead to a more frugal way of life for some, while waiting for huge productivity jumps. We simply lived beyond our means.
Carbon removal will not replenish our stock of natural resources or contribute to the creation of consumer goods, by generating energy for example. Quite the contrary, it will consume some at a time when it will no longer be so ubiquitous, thus probably further eroding an already affected GDP growth. Even in this new framework, carbon removal (and especially DAC) can hardly be seen as economically productive. It will simply mitigate some of the damage of an outrageous past.
Time for the brave: we must do it anyway
Our only hope is to include in our new economic logic the fact that, in the absence of carbon removal, the already limited stock of natural resources will be even more difficult to exploit, because of the devastating consequences of climate change. No Green Growth here unfortunately, maybe simply a less altered potential.
The key then probably lies in a sufficiently accurate modeling of these risks to allow good decision making. Not easy for such complex and distant phenomena.
It is difficult to blame those who might think that CO2 removal is equivalent, on an indvidual level, to:
1. pay to fix the roof
2. in probably poorer times
for fear of future unrepairable damage, i.e. completely uncontrollable climate change.
I have no solution other than to hope that we are wise enough.
In Part 3, we’ll see where we stand on this path.
PS: Thank you to all those who took the time to discuss this topic with me over the past few weeks. I do not mention their names as I do not want to give the impression that they endorse all of this reasoning.
