Carbon Capture

Sounds like the most feasible way of making graphene at commercial levels uses methane for the carbon source.
This Scientist Invented a Simple Way to Mass-Produce Graphene
The same with the nanotubes.
Carbon nanotube - Wikipedia, the free encyclopedia

 

cost nano tubes

Definitely you can make nano tubes and graphine with methane. Unfortunately you also need additional energy, which will typically come from oxydation of the hydrogen released in the catabolism of the methane. Since the demands of hydrogen are so much higher than for these substances, how will manufacturing them justify the added costs of producing hydrogen this way versus smr. Most of the graphine would never be used, or we would need to find much higher new uses.

 

My understanding is a carbon electrode arc makes them in different media:

Carbon Nanotubes, Production Methods for Carbon Nanotubes Including Arc Discharge, Laser, Chemical Vapor Depsition and Ball Milling by Cheap Tubes Inc


Bob Wilson

 

Sure we can look at the clinton carbon tax plan, and how it used some of the money to ... subsidize still using coal. That's what happens when you put it in congress and horse trade. No I was giving you the amount you would need to make carbon free hydrogen competitive with gasoline. If you include carbon in hydrogen, it puts out about the amount of ghg as a hybrid, so no amount of tax short of that high level will do it.

If you are going to take decades, infrasture would be built without the tech, and it would cost even more to replace it. Same conclusion.

Think of it this way. Old coal's main cost is maintenance of old coal plants. If you increase the price of carbon dioxide, ocgt will also pay, making you need a much higher tax to shift from coal to natural gas and renewables. Then you are going to leave it to congress to decide how to divy up that extra tax money, and of course if we look at the last plan they gave a lot of the money to coal interests, because the lobby is so powerful. Or lower tax, but only tax coal and gasoline. If you tax coal $50/ton ($0.025/kwh or $0.025/kg co2) and natural gas nothing it will transistion to natural gas and ghg will be reduced. If you tax the carbon in the natural gas too, you need $0.05/kg of ghg to do the same shift. We probably need $0.1/kg of ghg to help reduce oil use, a totally different number. A flat tax on ghg will not reduce ghg as much as smaller but appropriate taxes on coal and oil. Once you go down the "fair" road, you get a much less effective tax. We can look at all the nasty pro coal loopholes in the cap and tax plans the house passed, but senate never took up, or the coal giveaways in the earlier carbon tax plan.

Sure. Now name the members of congress that will pass that socially and economicly just distribution after they have to put in that much much higher tax levels?

European cap and tax plan was supposed to do this. It reduced coal use much less than expected. It mainly shifted countries that burned the coal The US which failed to pass a plan has reduced coal more.
British columbia has one of the better carbon tax schemes if everything its taxed.
http://www.economist.com/blogs/americasview/2014/07/british-columbias-carbon-tax
Its level though $30/ton of carbon dioxide would favor SMR over any sequestration of carbon in the production of hydrogen. About 6 tons of carbon dioxide are produced for each ton of hydrogen, or cost per kg would only be $0.20/kg of hydrogen, much cheaper than the extra natural gas. To do that you would need a much much higher tax on the order of $500/ton.

 

iplug. Pick any carbon tax you want. If you make it high enough to make hydrogen this way, what will electricity prices do? Plug in the numbers. No one has proposed a carbon tax that high for good reason.

I'm not trying to argue. I think you think there is magic here. Work some numbers. Tell me how do pass a much higher tax than british columbia, and what that will do to the US economy.

 

Don't forget current steam reforming process is CH4+H2O ---> H2 + CO2
so you are making a lot of the H2 from water....sort of like electrolysis.

Therefore the current process not only uses a relatively low CO2 fuel (nat gas) but it also gets a lot of H2 from water.

Only if we have some kind of extreme view that all fossil fuel use must be quickly stopped, do we have to invoke the concern that the clean nature of the current H2 process is not clean enough.

 

Correct:

I wanted to compare and contrast three processes:

• liquid tin reduction of methane to carbon and hydrogen
• electrolysis of water to oxygen and hydrogen
• steam reform methane to CO{2} and hydrogen

If CO{2} is not a problem, steam reformation works fine. But other than injection back into the gas field to increase production, sequestration of CO{2} never made sense to me. Making hydrogen by electrolysis works if the energy is free but it seems inefficient if we have methane feedstock and tin.

Now we've assumed the tin reduction leaves just carbon black. However, my reading of carbon nano structure formation suggests there a catalysts that may enhance formation of nano particles. Cobalt was mentioned but there may be more. So I see this as an area where research is likely to find something clever to make the carbon into something more easily made into a useful structure. At a minimum, I would wonder if diamond dust in the molten tin might grow grain size.

This is why this new approach is interesting. We may find ways to separate the carbon from the methane and increase its value added content.

Bob Wilson

 

First is
methane cracking. Its a process discoverd in the 70s or 80s and used since 1999. They are proposing a different reactor. The main reaction is CH4 + energy (maybe from combustion of CH4) -> C + 2H2.
KIT - KIT - Media - Press Releases - PI 2015 - Crack it! Energy from a Fossil Fuel without carbon di-oxide

Ok, in the lab they can get a 78% conversion of C-H energy to H-H energy, but does not provide any O=C=O bonding energy.
Do we get some magic diamond dust for free?

You pay for the methane and you pay for the reactor, if it makes it out of the lab. No free energy, it comes from the methane.

Your second method electrolysis you pay for your electricity. If its carbon free electricity so will the hydrogen. According to NREL the cheapest source of renewable electrolysis is night wind. Its not free but may indeed be less expensive than cracked methane. You need to know the price of each

The current method is SMR where The energy of oxidation of the carbon is used to separate water. This takes place in 2 reactions that reduce to
CH4 + 2H2O -> CO2 +4H2 + energy

Why would this cracking be more valuable than the cracking we do today to create carbon black? Rember the reason we don't create more carbon black when making hydrogen is the world uses a lot more hydrogen than carbon black. If we transition transportation to hydrogen that means even a smaller percentage of carbon black is needed than today (about 3%).

This is a fine way to make carbon black, but a pretty bad way to make hydrogen. As posted lots of methods to use methane to make nano tubes, graphine, etc, but no great new ways to make hydrogen without producing carbon dioxide, without adding cost, which today is a bigger problem than carbon dioxide.

 

As long as we have a shortage of CO{2} in the atmosphere, steam reformation wins: CDC - Immediately Dangerous to Life or Health Concentrations (IDLH): Carbon dioxide - NIOSH Publications and Products

Other human data: Signs of intoxication have been produced by a 30-minute exposure at 50,000 ppm [Aero 1953], and a few minutes exposure at 70,000 to 100,000 ppm produces unconsciousness [Flury and Zernik 1931]. It has been reported that submarine personnel exposed continuously at 30,000 ppm were only slightly affected, provided the oxygen content of the air was maintained at normal concentrations [Schaefer 1951]. It has been reported that 100,000 ppm is the atmospheric concentration immediately dangerous to life [AIHA 1971] and that exposure to 100,000 ppm for only a few minutes can cause loss of consciousness [Hunter 1975].​

So we're running close to 400 ppm giving us 50,000/400 ~= 125x safety factor. Good thing long term exposure to elevated CO{2} has no adverse effects on more sensitive human life phases. It would be a shame if long term, CO{2} exposure reduced intellectual activity leading to an inability to set a safe CO{2} limit.

Personally, I like some of the mechanical characteristics of carbon nano tubes and particles. Having a bulk source as a by-product of H{2} formation would be a win-win. Compared to electrolysis, a methane feedstock would be the way to go . . . assuming it can scale.

Bob Wilson

 

Actually no shortage of methane in the ground or carbon dioxide in the air.

The US produces 9 Million metric tons of hydrogen per year. This doesn't include much hydrogen for transportation, but if its SMR it produces about 60 million metric tons of carbon dioxide and would consume about 23 metric tons of methane.

If we eliminate it from hydrogen production perhaps carbon dioxide drops 1% but natural gas consumption in the US goes up 4%. Not really a big deal but not the low hanging fruit.

How much of U.S. carbon dioxide emissions are associated with electricity generation? - FAQ - U.S. Energy Information Administration (EIA)
76% of electrical generation ghg comes from coal
How much carbon dioxide is produced by burning gasoline and diesel fuel? - FAQ - U.S. Energy Information Administration (EIA)
83% of transporation ghg comes from oil

Agree we can solve 1% of the problem spending a bunch of money here. Of course if we apply it to power plants, not just hydrogen, price of natural gas goes up, and coal is retired is more slowly, increasing ghg versus the business as usual case.

It also makes it less competitive with oil for transporation, probably slowing down transition away from oil and hence increasing ghg versus business as usual case.

But by all means, yes you can save 1% there. How do we reuduce the bigger problems of coal and oil?

And yes to iplug - a carbon tax would reduce oil and coal more than the business as usual case, but not support methane cracking for hydrogen.

Methane feedstock makes economic sense there, just not methane cracking to produce the bulk of hydrogen the country uses.

We could of course use methane cracking for hydrogen ccgt plants that would be about 30% efficient but give off no carbon dioxide. That would be enough to raise natural gas prices in the US to move some natural gas intensive industries to china, where they produce more ghg.

 

Bob @32 would want to read article available via

EHP – Associations of Cognitive Function Scores with Carbon Dioxide, Ventilation, and Volatile Organic Compound Exposures in Office Workers: A Controlled Exposure Study of Green and Conventional Office Environments

before choosing a 'safe for thinkers' CO2 level.

Marine acidification is quite another thing.

 

I'm not sure we have much choice any longer. OCO-2 has already shown there are local CO{2} concentrations well in excess of 400 ppm, which is a point source record. So now I'm beginning to think office plants may make more sense . . . point source O{2} generators. <grins>

Bob Wilson

 

I think it should be noted what concentrations you are talking about. The green levels in the study are 550 ppm, and the current building codes are 945 ppm according to the study's non green ventilation. The study is really about proper ventilation, and is quite off topic here, where hydrogen manufacture has little to do with indoor levels at office buildings.

 

It isn't like we have to sequester all the CO2 produced by SMR.

"CO2 is not new to refrigeration. Its use began in the mid-nineteenth century and steadily increased, reaching a peak in the 1920s. Its use declined with the introduction of chlorofluorocarbons (CFCs) that operated at much lower pressures. Use of CO2 continued, but chiefly in cascade systems for industrial and process applications. Recently, strong interest has been shown in CO2 as a refrigerant by vending machine manufacturers. There are also possibilities for other light commercial refrigeration applications, as well as for residential air conditioning." - CO2 As Refrigerant: The Transcritical Cycle

CO2 as a refrigerant is making a come back with commercial heat pumps, and possibly residential ones. It has a higher temperature output than current ones, but it needs higher pressures and larger lift temperatures.
"A standard gas- or oil-fired boiler may deliver 180°F water for hydronic heating, and return water in the heating loop at a temperature of 150°F after delivering it’s heat through baseboard radiators. So the boiler has to “lift” the water from 150°F to 180°F. That isn’t enough lift for a CO2-based heat pump. The EcoCute needs a minimum of about 45°F of lift to function effectively." - https://www2.buildinggreen.com/blogs/heat-pump-using-carbon-dioxide-refrigerant

 

Here we can pluck carbon dioxide from the air to manufacture it, outside the hydrogen plant.

Remember NREL estimates lowest cost hydrogen for transport is distributed SMR. This makes carbon capture difficult. Central SMR or wind electrolysis adds to cost slowing adoption or the tax payer picks it up. FCV are lower ghg than gasoline vehicles which makes adding to the cost possibly increasing ghg versus not doing it. Again all the hydrogen today maybe accounts for 1% of US ghg footprint.

Capturing at new ccgt power plants though would save much more, still lets look at the figures. Coal electricity currently is about 28% of ghg in the US. If you would convert half of it to ccgt without sequestration that would drop production by 9%. If you sequestered 100% it would only drop production by another 5%, and the costs of sequestration may slow that transition. Transitioning also makes renewables cheaper to integrate into the grid.