Slashdot is powered by your submissions, so send in your scoop

 



Forgot your password?
typodupeerror

Comment Re: Energy in? (Score 1) 156

If you had a 10m^2 column and a superficial velocity of 1m^3/sec, you could process about 36,000 m3 of air an hour per column, so you'd need 50 columns to process the 10 second residence times. That's a lot of columns. Then you'd need dozens of distillation columns to separate the methanol. And amines degrade at higher temperatures, so that would need to be replenished.

Comment Re:Energy in? (Score 4, Informative) 156

Pure amines are expensive, and purifying water isn't cheap at the volumes this would need (see my other notes).

Note the process says it's aqueous, and therefore liquid. The temperature is 125-165 degrees, above the normal boiling point of water. Steam tables say 6 bars/atmospheres of pressure at 165 oC for pure water. 6 atmospheres isn't too bad for a pressure vessel, but you will need some engineering behind it.

Condensation requires energy, especially if you need a vacuum.

 

Comment Re:Energy in? (Score 2, Informative) 156

There are 44.6 moles per cubic meter of air. At 300 ppm, or 0.03% CO2, that would be 0.013 moles of CO2, at a 70% conversion rate you'd get 0.01 moles of methanol from 1 cubic meter of air. 1 kilogram of methanol (which isn't jet fuel, but never mind) is 31 moles of methanol. A 737 burns 3 kilograms of jet fuel per mile, let's say you want 6000 kilograms per trip. That means you'd need 3100 m^3 of air for one kilogram, or 18,600,000 m^3 of air. Assuming a residence time of a day for a facility to produce enough jet fuel for one flight, you'd need a facility with a total volume of 18,600,000 m^3. I'm not really sure it's cost effective to fly out a facility that as a minimum would be about 264 meters long, wide, and high. If the residence time were an hour, it would be about 100 meters on a side.

Another application is needed, this one won't cut it.

Comment Re:Energy in? (Score 5, Informative) 156

From the article:

"To produce methanol from CO2 in the air, the researchers at USC's Dornsife College of Letters, Arts and Sciences first bubbled captured air through an aqueous solution of pentaethylenehexamine (PEHA), an ammonia-derived organic compound with multiple amino groups that – at raised temperatures – helps form chemical derivatives from alcohols. They then added a catalyst made from ruthenium (a member of the platinum group) to promote hydrogen attachment to the CO2 when the mixture was subject to high pressure.

The solution was then heated to around 125 to 165 C (257 to 359 F), and around 79 percent of the CO2 was converted into methanol. Though the resulting methanol was still mixed with water as it was produced, the researchers state that it can be easily separated using simple distillation processes. In addition, with the new method operating at such comparatively low temperatures, minimum decomposition of the catalyst meant that the researchers were able to repeat the process five times with minimal loss of the catalyst effectiveness. It also uses a homogeneous catalyst (that is, a soluble catalyst in solution with the chemicals it is reacting with) resulting in a simpler and faster "one-pot" process."

So they have to procure an amine in the pure form, mix it with purified water, heat it to 125 to 165 oC (a lot of energy, also under pressure), bubble the air through it (requiring at least the same pressure as the solution so there wouldn't be backflow) then recover the product using distillation (energy intensive). It's good chemistry and interesting catalysis, but I don't see how it will be cost-effective.

My guess is it would be cheaper to let a tree reduce the CO2, chop it down, and make the wood alcohol from that.

Comment Re:This is completely awesome (Score 4, Informative) 98

They aren't intending to generate energy with this reactor; the goal is to sustain plasma at temperatures high enough to eventually get to fusion. The article says they are at 80 million deg C, which is about 7 keV. They need to get to 14 keV for a D-T reaction (look at the minimum for the Lawson Criterion) . That's excellent work, and if they can sustain it for thirty minutes, even better. When they are done, the design will be proven and then they can do the harder problem of building a reactor that can withstand the neutrons and recover the heat for a secondary cycle.

Comment Because you're asking... (Score 1) 1838

I appreciate the openness and candor of your post. My guess is others see that too. Most will recognize that you bought the site as a business, and are fine with clear advertisements; spam stories have a smell that some (like me) don't like.

Others may not like my requests, but here goes...

1. The ability to edit a post after final submission. I know you're supposed to have it perfect, but sometimes you scerw up.
2. If mod points are awarded, let the user keep them so there is no need to rush and use them. Also a little transparency about how they are awarded...sometimes I'm on a trip and I don't log in for a week and I don't get mod points for a month.
3. A certain person who shall not be named received preferential status to post incredibly long, banal, and tedious analyses that would really bring out the worst in the crowd. If that person had to have the posts make it on merit, it would be appreciated,

Good luck.

Comment What would they expect him to do? (Score 2, Insightful) 186

The 'no-poaching' compact was an agreement among chief executives. I know someone will drag this down to Godwin's Law in a minute, but he was doing as he was ordered. Are people expecting him to go to Eric Schmidt and Steve Jobs and tell them that he wouldn't follow direction? If he did, he'd get the opportunity to join the keyboard punchers at Wikipedia Editorial.

Are there any other reasons that he shouldn't offer advice on a board of a non-profit company?

Comment Re: Sweden worries about theirs too... (Score 1) 319

Studsvik in Nyokping is a world leader in nuclear reactor related research, and the Swedes are one of their biggest customers. They are one of the few places with the capability to do detailed nuclear fuel analysis.

Not to mention that the Swedish plants collect an enormous amount of data, test new technologies, and share the results with the world.

Slashdot Top Deals

Just about every computer on the market today runs Unix, except the Mac (and nobody cares about it). -- Bill Joy 6/21/85

Working...