301–310 of 347 posts
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How do you expect humanity to get to pre-industrial revolution carbon dioxide levels without atmospheric extraction?
The US could halve their emissions and still emit at the same level of an industrialized country like France. A good starting point is to invest more in nuclear energy.
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It is ironic as Bangladesh is going to be one of the countries hardest hit by rising sea levels and climate change.
Which is why it’s in their interest to develop economically as fast as possible so they can be best prepared for the future. The Netherlands handled a similar degree of their land being underwater using 19th century technology. But there is zero appetite for curbing growth. Bangladesh is a miracle of capitalism. When my dad was a kid 1 out of 3 children died by age 5. Now it’s 1 out of 40 and the life expectancy is 7…
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I don't see how we're going to use CO2 as energy again. It's not like the original hydrocarbons we dug up.
Right, which is why mostly the idea is to just bury the CO2. However, if you do want to make fuel from it, say for airliners, then it's totally possible, you just have to add hydrogen, and more energy than you'll get from burning the fuel. E.g. the Sabatier process to make methane.
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If you look at a map of all airline flights there are many thousands of short-range flights. Replacing them all with trains would be interesting. Just the right-of-way property transactions would be daunting. Look at California as a lesson in how this can't be easily done. The other thing is, people move around. Airlines can change flights easily to map to demographic changes; that's a major strength of air travel. N…
It's much easier, IMHO, to switch over these short haul flights to electric aircraft than to High Speed Rail in the US. By the time even one major new HSR route will be finished, we'll have certified and be flying electric passenger aircraft with just as much speed and just as long of a route (500 miles) BUT with ability to go anywhere in the country by hopping.
I think biofuels might be a better option for aviation until the tech has time to catch up.
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Right, which is why mostly the idea is to just bury the CO2. However, if you do want to make fuel from it, say for airliners, then it's totally possible, you just have to add hydrogen, and more energy than you'll get from burning the fuel. E.g. the Sabatier process to make methane.
But if you already have loads of hydrogen to play with you might as well just burn that, right?
Moreover, each glacial period ends with CO2 levels lower than at the end of the preceding one. The last one ended with CO2 levels not too far from starvation for photosynthesis. At the current rate of CO2 depletion we were headed for mass extinctions in just a few more glacial periods. Bringing CO2 up above 400ppm at the end of the current interglacial will extend life on Earth by a lot, possibly millions of years.
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> It's probably still cheaper to avoid emitting the CO2 in the first place, but that does put an upper bound on the cost of reaching net zero. It seems hard to believe that removing CO2 from the atmosphere could ever be less expensive than not emitting it to begin with. You're working against thermodynamics. So the whole thing seems like a fraud. An excuse to keep emitting CO2 while claiming that you'll do something…
Sadly the amount of CO2 in our atmosphere even if we stopped polluting today. Will still bring about huge negative effects down the road. We need to decarbonize our society(listed first because it’s the first priority) AND remove CO2. Source & a great read: https://www.orbuch.com/carbon-removal/ If you want to learn about carbon dioxide removal check out AirMiners: https://bootup.airminers.org/ they have a useful sel…
Once we get closer to zero emissions it makes more sense to think about capture IMO.
Edit: oh wait I think you are saying the same as you mention reduction is first priority, sorry.
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If you look at a map of all airline flights there are many thousands of short-range flights. Replacing them all with trains would be interesting. Just the right-of-way property transactions would be daunting. Look at California as a lesson in how this can't be easily done. The other thing is, people move around. Airlines can change flights easily to map to demographic changes; that's a major strength of air travel. N…
It's much easier, IMHO, to switch over these short haul flights to electric aircraft than to High Speed Rail in the US. By the time even one major new HSR route will be finished, we'll have certified and be flying electric passenger aircraft with just as much speed and just as long of a route (500 miles) BUT with ability to go anywhere in the country by hopping.
Current batteries have an energy density of 90-190 Wh/kg, depending on the specific chemistry. Jet fuel on the other hand has an energy density around 12,000 Wh/kg. Obviously some amount of that will be made back up with the relative light weight and high efficiency of electric motors, but that is a very step energy difference to overcome.
A quick bit of Googling says that turbofan engines are about 40% efficient, while triple phase electric motors are roughly 85% efficient. Given the 3,000 nautical mile range of a 737NG, some back of the envelope math says that an EV equivalent would have a range of about 100 miles at best[0]. Forget LAX -> SFO, this isn't even enough to get you from LA to Bakersfield. And even 100 is optimistic, given that the FAA requires that all planes have extra fuel for diversions, weather, holding, etc.
At this point, I suspect it might be easier to refine kerosene out of capture CO2 using excess renewable energy than it would be to make an EV 737 replacement.
0 - I'm obviously not accounting for weight and aerodynamic differences, which are beyond my capability to estimate, but I doubt that would make a significant difference. I'm also assuming that we're using Li-Ion Cobalt batteries, which have the highest density. The more common Phosphate chemistry makes these numbers even more bleak.