In this version of Is it too late?, we talk with Dr. Ryan Hanna about his work with direct air capture (DAC) systems. Along with his colleagues, Hannah wrote a paper detailing a more realistic path towards addressing the climate crisis.
Specifically, they found that resources akin to a wartime funding drive are what it's going to take to avoid dangerous levels of warming. Here, Hanna spoke with us about this paper and about how we may need to rethink our approach to the climate crisis.
Can you explain how direct air capture works? What would these systems look like and how would they affect our environment?
At the most basic, fundamental level, the DAC process is a chemical binding or absorbing process in which CO2 from the ambient air is grabbed onto chemically with different kinds of molecules.
They grab CO2 from the ambient air and then concentrate it. And then, with a little bit of heat and electricity, they can be released from those bonds in a very pure form. Then, you can direct the CO2 to where you want it to go – whether that's to a greenhouse that's sitting next door to the to the DAC plant or whether it's into a pipeline for dedicated storage underground.
In principle, that's it. You put electricity and heat into the system, you chemically bind CO2 from the ambient air, and then you can release it in a very concentrated form outside of the atmosphere, thereby removing CO2 from the atmosphere.
So, you can picture a big industrial chemical plant or a power plant, and it would look to the eye something like that with one major difference. That is these massive contactor pads that are needed to actually bring the CO2 in the ambient air into contact with the chemicals that are going to bind to it.
You’d have these very, very big contactor pads that could stretch the length of a football field. So, relative to other negative emissions technologies – technologies that we could use to actually remove CO2 from the air – the footprint is actually quite small relative to other options. But compared to what we're used to, they're still quite big.
These DAC systems won't solve the climate crisis by themselves, right? We need to cut back on emissions as well, correct?
Yeah, that's absolutely right.
The Intergovernmental Panel on Climate Change’s (IPCC) modelling is pretty consistent in showing that in order to meet the warming targets that are of interest to us – keeping warming to 1.5 or 2.0 degrees Celsius by the end of the century – we need to decarbonize our economies pretty quickly.
That’s where we get a lot of push from certain groups about decarbonizing US electricity by 2035. Or even sooner with sort of broader, economy wide, net 0 pushes by about 2050 or 2060.
That’s a timeframe we think about for decarbonization, or getting the CO2 out of the economy that's already there. In addition to that, to stabilize temperatures, we know we need to also remove CO2 from the atmosphere that we've already put there. That's where these negative emission technologies come into play.
Moving towards your work specifically, can you explain what you and your colleagues were doing?
Our purpose with this paper was to complement what the existing literature on negative emissions was telling us and showing us. Most of the literature is based on these big, integrated assessment models that the IPCC uses and that the global climate and energy community use to show what the least-costly pathways are into the future to get all the carbon out of the economy.
They tell us which technology options are better, which are worse. They're very complex, and they couple the economy to the energy system and to the climate system. They essentially say “moving into the future to 2050 and even beyond, we have to take steps A, B, C, and D. And we can do them in this way, so we have this menu of options to limit warming.” Within that overall pathway, there is a role for negative emissions.
Our research and our reason for doing this paper was to take more of a reality- or policy-informed approach to understanding the role for negative emissions. These IPCC models, they're very top-down, technocratic, where an omnipotent hand can reach in and sort of pull the levers.
That's great because it shows you what the potential or the ideal is. Politics and the way that technologies emerge and diffuse is actually in reality very messy and very hard to explain and to model. Our purpose was just to do something from the bottom up.
If countries or nations got together and recognized the climate crisis for what it is – something that demands some urgent action – and they pooled their resources together on a wartime-like footing, we wanted to know what that would produce in terms of negative emissions. Things like how much CO2 you can remove, how many plants the money would actually deploy. And then ultimately how those plants and the CO2 that they remove would affect global temperature rise and CO2 concentrations in the atmosphere.
Conceptually, it's a very simple analysis because it just says “okay, if we just dedicate these funds in the same way that we would funds to war, what can we get in terms of backstop on climate change and rising temperatures?”
In the paper, there was a lot of discussion about scaling up the deployment of DAC systems dramatically. Can you talk about the obstacles in the way of this goal?
It’s in the same way that any new technology takes a lot of time to diffuse into the market.
If you're following the decarbonization trends throughout the various sectors, pick the technology that you're interested in and look at its diffusion curve. Whether it's solar photovoltaics in the last 15 years, whether it's wind turbines that go back a little bit farther, or electric vehicles right now – the inertia of the energy system is just very strong.
Just basic math and these immutable laws of scale-up say that we should be starting now. We should be deploying initial plans now. We should be putting incentives and market conditions in place now. Governments should be funding this now. ~ Dr. Hanna
It's like a big oil tanker. It’s moving at 17 knots, and if you want to make a turn, you have to put a lot of pressure and force and energy into making a turn.
We need a lot of time and space and effort and energy and money. Historically, that's just the way the world works. It’s not a physical immutable law, but it seems to be sort of a law of human societies.
When we think about DAC and its potential scale-up effects, the short answer is that we really don't know how fast it could scale up. But if we simply take analogs from other technologies – if we want DAC to reach some scale where it actually is contributing meaningfully to climate change, which is something like maybe a couple of gigatons of CO2 removal per year by 2050, that's very ambitious.
Just basic math and these immutable laws of scale-up say that we should be starting now. We should be deploying initial plans now. We should be putting incentives and market conditions in place now. Governments should be funding this now.
There’s one mindset that's often in the literature and it says “focus on conventional mitigation now. Focus on solar, focus on wind, get all the electric vehicles out there. Decarbonize the economy, and once that effort is done, then let's work on negative emissions, DAC, and all the rest."
That doesn't work mathematically because the scale-up times are so long that you'll have seen all of the warming and temperature rise by the time you actually get the negative emissions scaled to where you want them.
Unfortunately, we need to walk and chew gum at the same time. We have to do both. We should be investing in the DAC certainly, but also other negative emissions technologies right now.
Is it too late, or when would it be too late, to deploy DAC systems in a meaningful way?
The lens through which we should think about this is simply that the longer we wait, the harder the challenge becomes.
If your models tell you that you need some quantity of DAC by a certain year – the longer you wait, the higher your rates of growth have to be to achieve your goal. The sooner you start, the more gradual the buildup can be.
In general, it’s a much better bet to go slow and steady. This gives opportunities to learn from your mistakes and really study the system and implement changes and course correct. If you're rushed and you're doing things fast, there's a chance that you are sloppy and inefficient and you waste money or you don't use it as efficiently as you otherwise could have.
So, I don't know that there's any single cutoff date by which I would say, “oh, now it's too late.” I think the broader principle is that if we want to do this right, and do this efficiently and effectively, we should be starting now so that we give ourselves as much time as possible.
“Too late” is sort of a misnomer. “Is it too late?” implies sort of binary “yes or no.” And really, it's a continuum. If we stop warming at 2.1 degrees, the world doesn't end. And if we stop warming at 1.9 degrees the world doesn’t just continue in peace and harmony – everything is a spectrum.
So, 0.1 degrees – whether it's 1.4 to 1.5 or 3.4 to 3.5 – is still going to bring incremental damages and it's worth stopping those damages if we're willing to do it.
There's always something we still can do. You never throw yourself into defeatism, I suppose.
