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this post was submitted on 29 Oct 2023
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You need to see it as removing the carbon generated by industries that can't be powered by clean energy, not removing carbon generated by polluting electric facilities.
Ship transportation will probably never be converted to battery power, so running wind farms just to remove the equivalent quantity of carbon released by ships from the atmosphere is a net positive.
What? Green hydrogen seems very likely as an alternative for shipping.
I think air/spacecraft are the harder problems to solve.
Green Hydrogen doesn't involve carbon capture. It's sourced from clean energy in the first place. I hope we do see it produce fuel cells that can be used for shipping.
It's unfortunately "Blue" or "Grey" Hydrogen that the fossil fuel purveyors are pushing to make themselves look like they care about the environment, though. Non-green versions do involve inefficient attempts at carbon capture. If you see someone talking about carbons and hydrogen, they're not talking about Green Hydrogen.
Yes it doesn't involve carbon capture, I was just replying to the comment that shipping needs carbon capture because of the fuel it uses. You don't need carbon capture if you change the fuel source which is entirely feasible for shipping.
The problem with hydrogen is its volatility, explosivity and transportability. In gaseous form it tries to escape from everywhere, when it leaks it can lead to big explosions, to transport it you need to keep it in liquid form which requires spending a whole lot of energy to keep it in that form or it needs to be at extreme pressure and, well, see number one.
In liquid form it also has less potential energy by volume than petrol, which means that for the same distance you need to use more space for fuel and less for actual cargo OR you need to fill up more often but then good luck making sure everywhere you fill up it's clean energy that's used to produce it.
Hydrogen is problematic, but all the points you've made are just typical disinformation on the matter.
First of all, hydrogen tanks don't explode. Even if you set fire on them, they'll simply leak and that leak will burn like a pressurized flame until the tank empties. Second, you can't really transport hydrogen in liquid form, as the boiling temperature for it is far too low (33K). They're always transported in gaseous form right now under high pressure, which is worse I'll admit. The energy needed to pressurize hydrogen though, isn't that much worse than LNG, since natural gas suffers all the same limitations as hydrogen as you've proposed.
In addition, the appeal of hydrogen isn't the energy potential per volume of fuel, but that it is quick to fill a tank compared to charging a battery.
The real downsides of hydrogen is that it is so small, it gets in between the molecules that make up any tank, making them brittle over time. Hydrogen tanks simply don't last very long, and are expensive to make if you have to replace them yearly. In addition, we haven't discovered a way to produce hydrogen at an economic level yet. The energy required to produce hydrogen far too high as it is, putting it at something like 20% or so.
Thus, the downsides of hydrogen isn't safety, but simply that it's very expensive from making it all the way to storing it.
But in this discussion we're talking about using it for cargo ships specifically... That means hydrogen tanks in an enclosed environment if an accident ever happens and compressed it has even less energy by volume.
The volume doesn't matter. Hydrogen can't ignite without the presence of oxygen in the first place, and there isn't any inside the tank. A new fully pressurized hydrogen tank is no more dangerous than a propane or natural gas tank. And we already ship natural gas in this state on specialized container ships.
If the tank leaks inside the ship is what I'm talking about, it's not open to the air, the fuel reserve is inside the ship and there's oxygen inside the ship. Hydrogen tends to leak a whole lot more than natural gas and an LNG cargo ship explosion is already a matter of concern.
Fair enough, but that strikes me as picking away at the edges of the problem. Maritime shipping represents about 3% of the total.. If research projects can offset that in ways that can be scaled up when we're ready, then that's great. But offsetting 3% here and 3% there doesn't accomplish much when net negative is where we need to be.
We need those projects and we need to describe their results in terms that garner and maintain support. That doesn't mean we should be diverting more than a few percent of our green energy to capture and storage at the expense of rolling out non-carbon energy production and eliminating carbon-based heating (and personal transportation?).
Trees are a lot slower at sequestration than most people think. They are also don't provide long-term sequestration, because they burn or rot somewhere along the line. Given that most existing forests are on land otherwise unsuitable for agriculture, every extra tree we plant takes cropland out of circulation. Without a way to take biomass out of the carbon cycle, it will never be more than carbon neutral.
The goal with trees is to grow them and not wait for them to rot, but instead use them as building material where the carbon they captured can be "frozen in place" for potentially hundreds of years and replant new trees in their place.
Places that produce electricity via polluting means shouldn't be investing in carbon capture but instead trying to make that production green to begin with, but places like Quebec where all electricity comes from renewables should invest in it to cancel the use of non renewables in other fields.
Okay, those tactics seem sound.
On the subject of wood specifically, I've read a few articles in the last decade or so about techniques for treating and using wood in ways that have the potential to dramatically reduce our use of concrete. Given the carbon footprint of cement, that seems like a positive development.