(If it took less, we could make a perpetual motion machine by burning and unburning coal)
Are we really supposed to expend as much energy as we expended in the entire industrial age just to remove the excess CO2 in the atmosphere?
Basically, yeah!
The last IPCC described the need for carbon removal in their last report[1]. The gist of it is that we'll need to decarbonize virtually everything, and use removal for the last 5-10% of residual emissions. That ends up being like six billion tons per year by 2025.
It doesn't compute.
I mean, you get my point, right? That 5-10%, supposedly we couldn't get it from some renewable source....we could only get it from burning fossils fuels. So where is the energy going to come from to suck the CO2 back out of the air again? By hypothesis, we didn't have any more renewable energy to use. But you can't clean the air by burning fossils fuels--thermodynamics says that you will always release more C02 than you could recapture.
1. Just stopping burning carbon isn’t enough. We need to take the existing excess carbon from the atmosphere.
2. It would be rational to move on an emergency basis to renewables + nuclear and burn less carbon in order to save future energy. But….well that’s difficult and we need energy now and humans aren’t famous for being rational all the time or having great long run planning in groups
So either we figure out how to eventually do it with renewables, nuclear or some other method, or we fail
Yeah, I just don't see that happening. E.g. suppose we only wanted to take the CO2 out of the air that we put in last year. It would take more energy to do that than we got from burning fossils fuels last year.
I don't remotely see how that would at all be feasible. I mean, yeah, 100 thousand of years of plants doing photosynthesis--taking that energy slowly but surely from the sun--would do it.
But the shorter of a timeframe you want it done, the more energy you are going to need--and since energy is conserved, that will eventually end up as waste heat and heat up the earth anyways.
* Let the temperature rise so fast that plants and animals will struggle to adapt. Within this century, or * Do some sort of geoengineering that limits the amount of solar radiation entering earth and manually manage the planet’s temperature.
#1 is the default and is doom. #2 seems what we’ll likely try. The barriers there are:
1. We somehow have to manage it globally.
2. It will let us continue emitting carbon, thus acidifying the oceans and leaving those ecosystems unable to adapt
It’s still the best option, hopefully we can actually do it.
If we want to avoid it we need a surplus of energy and a way to store the excess carbon in a reasonable cost effective way. But it will almost certainly take more energy than was produced by burning it in the first place.
Animals and plants have fairly narrow bands of acceptable temperature and don’t have air conditioning. Mass extinction is hypothesized at ~5 degrees of warming from pre industrial levels. Note that land warming will be higher than average warming, as the average includes the oceans.
Sounds like the obvious choice...but can you put some numbers to it?
1. How much C02 do we need to take out of the air to prevent your doomsday scenario,
2. How fast do we need to take it out of the air?
3. How much energy would it take to do that?
4. What are the side effects of generating that much energy, and expending it according to the timeframe of #2?
HellifIknow the answers, but I can do a bit of Fermi-style estimation, and no matter what numbers I plug in, it just doesn't make any sense.
Depending upon the answer to #2, we might not even be able to: 1. convert 100% of our energy generation to carbon-neutral sources, 2. Install 2.5-3x (depending upon how efficient carbon capture can become) the amount of power generating capacity we already have--again, all from carbon neutral sites 3. And then start extracting C02 out of the atmosphere at the same rate we put it in.
#1 alone seems like it will take decades, to say the least. #2 says that doing #1 is going to be 2.5-3x harder. We will have to not only supply our current power budget, but also the energy needed to power these global scrubbers.
And is the rate in #3 even enough?
> Animals and plants have fairly narrow bands of acceptable temperature and don’t have air conditioning.
Yeah, unless I'm very mistaken, they are screwed. It might not even be physically possible to do steps #1 through #3 in time to save them.
The more likely scenario is we try to geoengineer and that buys time and we eventually get the energy to actually remove the carbon over a longer timescale.
Lot of uncertainty in that route but I don’t see a better one. But ultimately the sooner we can shift away from burning carbon the less energy we’d need to remove it in the future.
For things like long-distance flights, jet fuel is way more fantastic energy storage than any kind of electrification can sustain. It may make sense to spend 2x that energy sucking CO2 out of the air. The issue isn't "total energy production" it's "storing energy in a small metal box and releasing it over 13 hours".
Of course, producing that jet fuel in a carbon-neutral way (e.g., from plant biomass) is probably a better solution than sucking the CO2 out of the air, but we'll need the latter anyway...
Of course, just like we'd all be better off not overfishing, but tragedy of the commons dilemma makes it hard to coordinate to stop that from happening. Not to mention, renewables have only become cheap recently, but we've been emitting for a long time.
1. You can't scrub the air using energy from burning fossils fuels--it puts more C02 into the atmosphere than it yields energy to take it back out again, and
2. In the scenario described, we were only able to provide 90-95% of our energy using carbon-neutral sources. That and #1 above means that we would not have the energy needed to scrub any C02 from the atmosphere. Burning fossils fuels at that point would be a net loss in power.
[0] https://caseyhandmer.wordpress.com/2023/01/09/terraform-indu...
Another thing to consider is that aviation only accounts for around 2% of global carbon emissions. If SAF ends up being harder to make than expected, it might end up making sense to keep extracting + refining some fossil fuels and mitigate them using some other means (mineralization, perhaps).
Cheap carbon dioxide removal could end up leading to some rather unintuitive outcomes.
You mean: “aviation accounts for around 2% of global carbon emissions”.
There is no only about it. 2% is actually a meaningful and substantial number when you consider the pie-chart it's sliced out of represents a collossal problem.
Flying will cost at least 2x as much as it does today.
Fuel accounts 30-50% of the costs of air travel. A straight doubling of fuel costs would not double air travel costs (although it would hurt)
The CO2 emitted from air travel wouldn’t necessarily need to be converted back to a very high energy molecule like jet fuel. I’m not a chemist, but I’m pretty sure there are polymers that you can bind the carbon into and not be nearly as energy intensive as recreating petroleum molecules.
Finally, wind and solar electricity generation are already generally cheaper than any fossil fuel generation besides nat gas. The EIA (via Wikipedia) had that at around 2x cheaper solar versus diesel generation, and solar and wind continue to see cost improvement.
All that being said, any carbon elimination scheme is going to have a cost, but the theoretical cost efficiency can be much better than if you assume energy is 1-1 with cost.
Flying will cost more, but not necessarily 2x more.
Plus that's only if we can't synthesize jet fuel from all that CO2 we're extracting from the air.
PD: Yes, you could use a not electrified railway, but simply makes more sense to electrificate all railways
If only trains were traveling at predictable routes and you could supply them with electricity while traveling. Let's call it an electric locomotive.
Planes, at least passenger yets, will never use lithium ion batteries. Which is why the industry is pivoting to "green" aviation field.
Planes is another problem.
I'm not sure that's the correct argument.
We only really need to expend as much energy to convert stuff into coal as was needed to turn it into coal in the first place. If we can do it more efficiently than Nature™ then we are energy positive since all the effort to extract it is already expended and (reading the terms & conditions) nonrefundable.
It seems to me... could be wrong.