I wonder if carbon capture actually makes sense, not from an economic perspective but from an energy perspective.
One way or another you're spending a lot of energy doing it. Using fossil fuel would not make sense as it would add to the problem you're trying to solve. Considering there's not enough renewable energy for all our current uses, wouldn't it be simpler to just reduce, and convert more things to renewable as they come available, which we'll need to do anyway?
Once we have a big surplus of renewable in the future we could look at this again.
It sounds to me like a pipe dream, a promise of a 'quick fix' for a problem that has no quick fixes.
And to be honest in order to actually reverse global warming and prevent some of the future effects we're already locked in to, we'll have to extract so much carbon that I don't see this happening in the next hundreds of years.
I am by no means an expert here, but a couple thoughts back from my limited knowledge:
1) I don't think all carbon capture necessarily requires a lot of energy input. Planting trees is a more obvious example of this - of course, the trees rely on the sun's energy so it's not "low energy" in that sense, but we weren't going to harvest that energy any other way anyways. It's possible there are other solutions that are like that.
2) If we have an abundance of zero or low-carbon energy in the future that doesn't exist now, it might not matter that taking carbon out of the atmosphere uses more energy than the energy we got from putting carbon into the atmosphere to begin with.
To be clear, I really wish we'd just spend the money and take the sacrifice to use a lot less carbon right now. It certainly seems like a much easier problem to solve than trying to suck it back out later, and relying on it to work seems like a dumb risk. Even if we're confident that we'll inevitably need some amount of carbon capture and that the R&D will happen to develop it at scale, there's a good chance that it'd be easier and cheaper to put less carbon in the air now than to do more capture later.
I don't even think you need "a lot of sacrifice" to stop emitting so much carbon. The EPA estimates that energy efficiency could cut emissions by up to 20%.
The trick is that most energy inefficient buildings and appliances are used by poor people who can't afford to upgrade or maintain to the latest and greatest standards, and massive funding for poor people is a giant lightning rod at least in the US. I know that in a previous house my utility was literally paying me to replace my fridge and air conditioner to reduce peak power demand, but I have no idea how widespread such programs are.
The problem with efficiency is that it's usually not tied to reduction. We need people to have more efficient buildings and to heat and cool them less. We need LED lighting with no more lighting. So, https://www.treehugger.com/energy-efficiency/are-we-using-le...
Put simply: INDUCED DEMAND
Just like roads or computer hardware (every improvement in hardware can get eaten up by people no longer caring about optimizing software efficiency or modest file sizes: nobody needs their cute family videos to be 4k HD etc)… we can easily use up ALL the gains if we are let to just do that.
We use more efficient building technology to support homes being larger and more luxurious than we need. Defeats the whole purpose.
We need to internalize the costs. Heavy taxes on the source of pollution rather than subsidizing the clean-up or the use.
If energy gets MUCH MUCH more expensive, people WILL upgrade to efficient tech and keep minimizing their use of it.
Trees are not a great solution. Their CO2 storage is basically static in terms of the amount, once the forest is grown it won't have a huge net capture anymore. We'd have to raze them and keep re-planting to do that. Which has obvious nature impact.
But I agree with your comment. Preventing is better at this point, especially while we're still emitting (and will be for a long time). I view Carbon Capture at this stage basically as a decoy from big oil to keep doing what they're doing.
If you have excess energy you cannot use at that moment, it may as well be spent removing carbon from the atmosphere. For example, if there's a giant field of wind turbines that are experiencing more wind energy than can be consumed, and there also aren't enough batteries to store it for later.
Having a more connected electrical grid so that you don't end up in this situation would probably be ideal, like what you're suggesting with using green energy to replace carbon sources.
You're right that it's not at all a quick fix, and that it requires a lot of energy. But it is the only sustainable solution: if we want to restore a preindustrial climate we're going to have to put the fossil fuel emissions back where they came from.
So we're going to need a lot of surplus energy to do it, and it will take a long time. Which means that we need to start the R&D now, scale it up when we have surplus sustainable energy, and plan for the time it will take to execute.
Concurrently, we need to push through the sustainable energy transition as fast as possible, and probably also figure out how to reduce solar heating of Earth while we do carbon removal over the next century or so.
I wonder if there is any point to go to a preindustrial climate though. By the time we get technology to the massive scale required to actually fix it, the worst effects will have already occurred. The climate will have already changed and we will have dealt with it one way or another.
Going back at that point will basically mean another climate change. One that will be mainly for the better but will again have impact on nature that will have adjusted in the mean time. It won't be a 100% positive. I wonder if that is really worthwhile. And if things will really get back to what they were; For one the arctic ice, would that build up again in the exact same places? They have a large effect on jetstreams so I'm not sure if things would really go back to the same way things were in pre-industrial times.
Also, in pre-industrial (and early industrial) times winters were really harsh sometimes. It wasn't all rosy either. I think around the 70s/80s the climate was the mildest though I didn't study it.
If carbon capture required unburning the carbon, you'd be right. But simply separating CO2 from air, or from flue gas, does not, in principle, require much energy at all.
One way or another you're spending a lot of energy doing it. Using fossil fuel would not make sense as it would add to the problem you're trying to solve. Considering there's not enough renewable energy for all our current uses, wouldn't it be simpler to just reduce, and convert more things to renewable as they come available, which we'll need to do anyway?
Once we have a big surplus of renewable in the future we could look at this again.
It sounds to me like a pipe dream, a promise of a 'quick fix' for a problem that has no quick fixes.
And to be honest in order to actually reverse global warming and prevent some of the future effects we're already locked in to, we'll have to extract so much carbon that I don't see this happening in the next hundreds of years.