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Breakthrough solar cell captures CO2 and sunlight, produces burnable fuel

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Re: Breakthrough solar cell captures CO2 and sunlight, produces burnable fuel

#151

Post by jcoffland »

shadowmint wrote: post #122
jcoffland wrote: post #114

Earlier quoted context omitted.

> Does the catalyst get used up, or crud up with contaminants, and if so, how fast? What limits the life of the system? What are the costs like? (Excessive catalyst cost has been a problem.) If you had actually read the whole article before commenting you would know the answer to these questions. Your questions about efficiency are however valid.

I read the article and the answers certainly weren't clear to me. '20x cheaper than some other catalysts' what does that mean exactly? 'special fluid keeps catalyst sites clean' does it get used up in the process? Is the fluid expensive and hard to manufacture? The devil is in the detail here. How exactly does this compare to other state of the art similar approaches? 10x cheaper? 2x cheaper? on par? I think it's pre…

I agree with your skepticism but even if the article included more stats there would still be many questions. The only way to prove conclusively that this is a viable method would be to produce it at scale.

Re: Breakthrough solar cell captures CO2 and sunlight, produces burnable fuel

#152

Post by eggy »

DougWebb wrote: post #142
im4w1l wrote: post #135

Earlier quoted context omitted.

The thing with falling-of-roof deaths is that they are poisson distributed. If 25 people fell off roofs then maybe if we are unlucky 50 people will fall off roofs this year. But no amount of bad luck will ever make 10,000 fall off roofs the year after. Deaths from fusion and nuclear on the other hand are very unpredictable. It is easy to imagine that year after year, no people die. And then suddenly millions of peopl…

Millions of people? Where do you get that number? We've had two devastating accidents with nuclear reactors, and one that came close to being devastating. All three were older designs that were more dangerous than the designs we could build today. The combined death toll is in the hundreds to thousands, at best. You don't get up to millions of deaths unless we start firing nuclear weapons at each other.

Exactly why I chose the geometric mean with the nuclear industry claiming less than a 100, and Greenpeace reaching for 850,000, that ballparks you to 9200. If you try and include hypothetical deaths decades later, you would also need to include coal-burning plants particulate causing respiratory diseases affecting longevity, and the fact that there is typically a higher radiation level on the perimeter of a coal-burning plant than right outside an operating nuclear power station. Nuclear looks better with each passing year in spite of the back pressure.

Also, I am not sure of the choice of the Poisson distribution suggested above. Roofers are experienced at walking on rooftops, and die due to, well, accidents. That and roofing work is fairly consistent. This number would follow some sort of normal or Poisson distribution, but homeowners are typically only used to a ladder to clean rain gutters out, not roofing or rooftop walking.

Death of roofers/installers during initial installation were the numbers I was quoting from Australia. I think homeowner fatalities will top the roofers in areas with increasing solar panel installations. I would think a Weibul distribution with a Beta of 0.5 would better suit this scenario to model all of the inexperienced homeowners cleaning their solar panels monthly, and then dropping off (no pun intended) after reports and education on working at heights diffuses into the populace.

Re: Breakthrough solar cell captures CO2 and sunlight, produces burnable fuel

#153

Post by ytpete »

semi-extrinsic wrote: post #136
danieltillett wrote: post #110

Earlier quoted context omitted.

Actually if the CO2 absorbent is efficient it is not much harder to capture CO2 from the atmosphere than from flue gas. The key really is the CO2 flux rate which wind provides. The real advantage of atmosphere capture is you can do the capture where the cost is lowest, not where the CO2 is emitted.

> The key really is the CO2 flux rate which wind provides. Indeed. This brings us to the issue of volumes. A useful carbon capture plant needs to capture at least 100 000 tons of CO2 per year (then we need "just" ~ 10 000 such plants). This means each of these minimal plants has to process an air volume of 250 billion cubic meters of air per year. At an air speed of 1 m/s (you can't flow too fast or there is no time…

Couldn't the membrane be folded or stacked so you achieve that amount of surface area in a far smaller floorplan footprint?

Re: Breakthrough solar cell captures CO2 and sunlight, produces burnable fuel

#154

Post by dang »

karma_vaccum123 wrote: post #55

I am Jack's middlebrow dismissal. Why not just type "pffft" and save us the tedium of pouring through your "references"? This is every comment you post.

Personal attacks are not allowed here. Please don't do this again.

We detached this subthread from https://news.ycombinator.com/item?id=12194564 and marked it off-topic.

Re: Breakthrough solar cell captures CO2 and sunlight, produces burnable fuel

#155

Post by daveheq »

Animats wrote: post #35

"Nanotechnology" again. It's just surface chemistry, people. It's nice that they can do this in the lab, but as usual, the PR is excessive. "The ability to turn CO2 into fuel at a cost comparable to a gallon of gasoline would render fossil fuels obsolete." At least get to pilot plant stage before issuing statements like that. Especially since UC Berkeley announced a similar breakthrough last year.[1] Wikipedia points…

If this technology's been around for so long, I wonder who's been suppressing it?

Re: Breakthrough solar cell captures CO2 and sunlight, produces burnable fuel

#156

Post by semi-extrinsic »

ytpete wrote: post #153
semi-extrinsic wrote: post #136

Earlier quoted context omitted.

> The key really is the CO2 flux rate which wind provides. Indeed. This brings us to the issue of volumes. A useful carbon capture plant needs to capture at least 100 000 tons of CO2 per year (then we need "just" ~ 10 000 such plants). This means each of these minimal plants has to process an air volume of 250 billion cubic meters of air per year. At an air speed of 1 m/s (you can't flow too fast or there is no time…

Couldn't the membrane be folded or stacked so you achieve that amount of surface area in a far smaller floorplan footprint?

If I understand it correctly, all the membrane area has to be exposed to direct sunlight.

Re: Breakthrough solar cell captures CO2 and sunlight, produces burnable fuel

#157

Post by maerF0x0 »

dredmorbius wrote: post #123
maerF0x0 wrote: post #94

Earlier quoted context omitted.

I dont know how much they differ but planting trees has lots of cost. I estimate the cost of planting is something like $3 per surviving tree. (Cause you usually over plant assuming many will die).

Depends on the tree. For some forestry applications, seeding is done from the air. Note that if you're growing wood for fuel, you're not worried about grafting stock, or the net health (much), or overcrowding (you can thin later if necessary), etc. Planting orchards is, as it happens, pretty expensive. But that's also a pretty high-end case, and the expected life is generally 20-50+ years. Upwards of 300 in cases (ol…

I was not referring to orchards, but for regular logging industry. Those cycles are about 60-80 yrs between harvests.
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