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Engineers are developing new ways to convert greenhouse gases to fuel

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Re: Engineers are developing new ways to convert greenhouse gases to fuel

#171
post #57

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Super interesting, thanks! Any idea what the timeline will be on your fund?

In the works now, will have updates in the next month or two.

Re: Engineers are developing new ways to convert greenhouse gases to fuel

#172
post #111
post #85

Earlier quoted context omitted.

Yes, and sort of. The ISS is constantly losing gas, I believe that the primary source of new O2 is actually electrolysis of water, not pressurized tanks, but that they do also have pressurized tanks as a backup. A person breathes out roughly 1kg of CO2/day, and it follows you breathe in about the same amount of O2, not an impossible amount of mass to resupply.

> 1kg of CO2/day which is crazy low if you put it in perspective and see that (gas powered) cars release about 0.2 kg of CO2 ... per kilometer.

The average trip in the USA is 10 miles ~16km, so 3.2 kg/trip, at the average ~4 trips per day that's like 12-15x more than a person.

https://www.bts.gov/statistical-products/surveys/national-ho...

Re: Engineers are developing new ways to convert greenhouse gases to fuel

#173
post #102
post #76

Earlier quoted context omitted.

Methane is fairly short-lived in the atmosphere, at only 12 years, so it probably wouldn't be particularly effective at terraforming mars. Perfluorocarbons or sulfur hexafluoride can stick around for thousands of years, so they would probably be a better place to start.

Current SF6 level (four orders of magnitude more heat-trapping than CO2, by weight) accounts for 10% of heat forcing. How the heck do we get that stuff out of the atmosphere? There is a replacement, now, for SF6, for use in power stations and wind turbines. Now the SF6 in use needs to be pumped out and disposed of safely, and SF6 actually banned. And, we have to persuade China to replace theirs too.

> Current SF6 level (...) accounts for 10% of heat forcing.

Source? This does not match what https://en.wikipedia.org/wiki/IPCC_list_of_greenhouse_gases says.

In my naive mind, Methane seems like the it could be a good candidate for removal from atmosphere: If you could just get it to react with oxygen, it turns into water and the much less harmful CO2, so you don't have to sequester anything, and the reaction is exothermic i.e. it already "wants to happen"... we would "only" need an effective yet cheap catalyst to make it happen at low temperatures.

Re: Engineers are developing new ways to convert greenhouse gases to fuel

#174

Earlier quoted context omitted.

If people were willing to work through the issues with nuclear power, running a bunch of nuclear plants to power the scrubbers would be semi-reasonable.

It's far more reasonable to use solar than nuclear for this, solar has leapfrogged nuclear now. The carbon capture startup founder of Carbon Engineering talks about how he got this wrong, and how they switched their plans from using nuclear to solar. Here's a talk from two years ago on this: https://www.youtube.com/watch?v=sYopOt9siLg Note that many disagree with his optimism on the carbon capture side of things, but…

What is a technologist?

Re: Engineers are developing new ways to convert greenhouse gases to fuel

#175

Earlier quoted context omitted.

Starting a greenhouse effect on Mars would help it become more livable by humans.

Do you realize the amount of effort we would have to put in to make it habitable? And the time scales involved?

There is a decent kurzgesagt video explaining what transforming a new planet would look like https://www.youtube.com/watch?v=G-WO-z-QuWI

Essentially it would be almost infinitely easier to reverse all climate change on earth than to make another planet livable but it is in theory possible.

Re: Engineers are developing new ways to convert greenhouse gases to fuel

#176
post #150

Earlier quoted context omitted.

Just remember that only the C part makes you lighter as the O2 comes from the air. So based on that number it's 375g/day (edit: it's 273g)

I get 273g/day? C is lighter than O. Also... this is a typical number for a typical lifestyle, I believe it can vary substantially if you exercise a lot. Also... I know nothing about wait loss, but surely a lot of the mass is in water?

Your body loses water every time you breathe. You lose about 1 cup of water each day, just from breathing.

Re: Engineers are developing new ways to convert greenhouse gases to fuel

#177

Earlier quoted context omitted.

It'd be much, much, more effective to hook up a nuclear reactor to the grid to take fossil fuel plants offline, and avoid releasing CO2 in the first place. Though in the long term, it might be useful to do what you propose to produce carbon neutral hydrocarbon fuel for things that need exceptional energy density. Like air travel or space launch vehicles.

> Though in the long term, it might be useful to do what you propose to produce carbon neutral hydrocarbon fuel for things that need exceptional energy density. Like air travel or space launch vehicles. Yes that's what I had in mind - thanks. I do remain sceptical that electric cars will save us. If everyone buys an electric car, and then plugs them in the evening to charge - I'm not sure the grid will cope very well…

Hourly priced electricity will be the future. Solar is creating this huge abundance of power during the day and electric cars are basically a huge grid of batteries. Since you are not using your car for the majority of the day and usually not during the middle of the day where peak solar kicks in, you can just plug your car in every time you leave it parked and then a charge controller sits and does nothing until power prices drop to the expected lowest price before charging. With some kind of fail safe where they charge anyway if no expected low occurred.

But another problem is that road construction itself is a huge cause of greenhouse gas emissions and isn't solved at all by electric cars. Only fewer and lighter cars would make things better. Personally I think electric scooters could replace a fair bit of car travel. The little sit down ones are sufficient to get you around for most trips and carry a bags worth of stuff.

Re: Engineers are developing new ways to convert greenhouse gases to fuel

#178
post #102

Earlier quoted context omitted.

Current SF6 level (four orders of magnitude more heat-trapping than CO2, by weight) accounts for 10% of heat forcing. How the heck do we get that stuff out of the atmosphere? There is a replacement, now, for SF6, for use in power stations and wind turbines. Now the SF6 in use needs to be pumped out and disposed of safely, and SF6 actually banned. And, we have to persuade China to replace theirs too.

> Current SF6 level (...) accounts for 10% of heat forcing. Source? This does not match what https://en.wikipedia.org/wiki/IPCC_list_of_greenhouse_gases says. In my naive mind, Methane seems like the it could be a good candidate for removal from atmosphere: If you could just get it to react with oxygen, it turns into water and the much less harmful CO2, so you don't have to sequester anything, and the reaction is exo…

Do you suggest releasing a catalyst into atmosphere? It may be dangerous, people tend to release methane, kids sometimes injure themselves by "catalysing" reaction of methane with oxygen by a flame source just for fun of watching flame farts. It would be unfortunate if these flame farts happened spontaneously as a sort of an embarassing social accident.

Re: Engineers are developing new ways to convert greenhouse gases to fuel

#179
post #116

Earlier quoted context omitted.

Liquid hydrogen LH2 electrically synthesized on-site at airports from excess peak production will be important in aviation after maybe 2035 (provided civilization doesn't collapse first). Aside from LH2's usefully extreme energy density, pumping less CO2 directly into the stratosphere would be good. We may reasonably expect production of the needed aerogel-insulated LH2 tankage to be mature by then.

Asking as someone only remotely familiar with hydrogen as a fuel: Don't you have the problem of tanks and pipes becoming brittle from hydrogen diffusing into the material? Are there existing/upcoming solutions for this? I was under the impression that this is a pretty fundamental problem with hydrogen being just a proton essentially..

Aluminum is supposed to be pretty tolerant of extra protons in its matrix. You might passivate the surface to be electropositive, to repel the ends of the H2 molecules as they try to weasel into the gaps. Liquified hydrogen is anyway much less mobile than gaseous hydrogen, and when used at atmospheric pressure, nothing is trying to force the molecules in.

Gaseous H2 at the extreme pressure people try to use is a much greater nuisance.

Re: Engineers are developing new ways to convert greenhouse gases to fuel

#180
post #116

Earlier quoted context omitted.

Liquid hydrogen LH2 electrically synthesized on-site at airports from excess peak production will be important in aviation after maybe 2035 (provided civilization doesn't collapse first). Aside from LH2's usefully extreme energy density, pumping less CO2 directly into the stratosphere would be good. We may reasonably expect production of the needed aerogel-insulated LH2 tankage to be mature by then.

You need to consider the volumetric energy density, not the specific energy (which is energy per mass). LH2 has a high specific energy but pretty low volumetric energy density which means that much larger tanks are needed to store the same amount of energy than for other fuels. The conditions for storage of LH2 and demands on materials in contact with LH2 are much harder than for e.g. methane.

Low mass density means you can't keep the LH2 in wing tanks. Inboard tankage might be unwise. Slinging tanks under the wings, alongside the engines, minimizes plumbing. It might seem like that would add a lot of drag, but aerodynamics is a very unintuitive science.
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