Power plants that convert all of their CO2 emissions into carbon nanotubes
phys.org
phys.org
The authors estimate that a "CC CNF" power plant would produce $835 of electricity and over $225,000 of nanotubes from a single metric ton of methane. At this point, economically, this is no longer a power plant: it is a carbon nanotube factory that has the side-effect of producing power. And if nanotubes are so valuable, the power generation part starts to look like a distraction: why not just pull the electricity off the grid and convert methane/CO2/coal/oil straight into nanotubes for less cost and complexity?
So really, this doesn't seem to be about power plants, so much as a (maybe) cheap way to make nanotubes from carbon. If we can incentivize people to make useful products out of all that CO2 just floating in the atmosphere, then maybe, just _maybe_, we can start fixing the mess we made.
Space elevator!
There will probably be some good applications, but I don't think it's a full replacement for metals.
I just crunched the numbers, and if everything sold on Amazon was made from 100% captured CO2, it would still account for significantly less than 1% of what we need to capture, transport and store.
And of course we also need to reduce carbon emissions, capture is not a singular solution, but it may help during the transition to renewables where we still need gas plants.
Is this really a shorter path than just planting more trees, which is both cheap and extremely low maintenance?
Burning fossil fuels can release an almost unbounded amount of carbon into the air.
So plant more trees? It's a continual process. It's not like you can plant a tree and say "Ok, I'm carbon neutral now!"
The current amount of carbon sequestered in all of the world's forests is ~600 giga-tonnes.
If we stopped all of our carbon emissions today, and tried to roll back to pre-industrial CO2 levels, we'd need to sequester ~270 giga-tonnes of carbon. Losing that much agricultural land is unrealistic - expensive as they are, it would be much less painful to switch our entire energy economy to renewables.
Re-forestation is part of the solution, but it's no panacea.
I hadn't meant to suggest it was. I'm merely saying that any approach to our carbon problem that doesn't include planting trees is inadequate.
Ahh, I misunderstood, my bad. I thought you were arguing that reforestation was not even worth the effort.
You don't need vast forests to capture carbon. You need one soon to be retired 30 year old panamax ship. A cargo hold full of ore (~50$/ton + 20$ powdering), and a on-board pump/aerator.
The burden of proof that "iron fertilization" (or any other geo-engineering technique) will even result in a net reduction in anthropogenic climate change — leaving entirely aside, you know, not actually being harmful — is on the people who want to do it. As much as CO₂, &c, is a problem that begs for something to be done, I don't think that's been adequately demonstrated yet.
ageofwant is satisfied that given the limited trials so far and the Russ George "experiment", which by all indications were wildly successful, large scale ocean seeding trials is called for.
Given the risks associated with doing nothing, and the relative low cost of a large trial, it would be silly, nay morally indefensible not to.
But the consequences of being wrong on some of the things being suggested to combat climate change could be tremendous, and in some cases even worse than the problem they're being used to solve.
I don't know where the balance that needs to be struck lies, but I'm pretty sure it's somewhere on the far side of:
"Welp, sounds good to me!" — some dude on the internets
Agriculture is a harder angle to attack; however, trees are excellent use of space: they store carbon for a period of time, they require low maintenance, they oxygenate the atmosphere, they can be planted cheaply and densely; harvesting them allows use of stored carbon (build with wood! Paper. Etc); they can be planted in areas that are typically not friendly to agriculture (eg mountains, places with extreme cold, etc). For the space we do have, there isn't much reason NOT to plant trees.
I would be interested in a comparison between different types of dense vegetation; eg trees vs grass vs moss vs algae, etc etc.
The obvious solution being to increase carbon/biomass per hectare in our urban and agricultural land.
>Losing that much agricultural land is unrealistic
Losing it, yes. But replacing it with agroforestry and soil building no-tillage agriculture would increase the food supply (mainly since bare dirt monoculture fields are so abysmal at utilizing sunlight compared to healthy engineered ecosystems). Similar story with replacing corn-fed CAFOs and compacted ranch land with sylvopasture and MIRG (managed intensive rotational grazing).
If it sounds unrealistic to replace our whole food system with something else, remember that there is no alternative. The modern industrial food system isn't a viable replacement for itself. That's all the word "unsustainable" means: it's not an ethical judgement, but a logistic certainty.
Dense planting means the canopy can prevent rain getting to the ground and the trees take a lot of the water that does get to the ground which means aquifers are not replenished.
The dry ground and dry trees pose an increased fire risk. Burning the tree releases any captured carbon, and a bunch of smoke.
New forests crowd out and change existing eco systems, meaning many animals are lost to the area.
Trees shade soil reducing evaporation levels. Trees also significantly reduce surface winds further reducing evaporation. Yes trees do potentially use more water which is exactly what you want, what is the purpose of full aquifers flowing into the sea ?
In Australia removal of trees has lead to increased salinity levels affecting 2 Million hectares (In WA alone) of arable land degrading vast swathes of it rendering it unusable for both modern agriculture and pre-agricultural "natural" use. This is precisely because the trees kept the high-salinity water table below surface root levels.
I'd be happy with merely replacing some of the forests that we cut down in the first place.
You know, if we're going to make arguments premised on human activity altering extant ecosystems, and all...
[0] https://en.wikipedia.org/wiki/Deforestation_during_the_Roman... [1] https://en.wikipedia.org/wiki/Geography_of_Iceland
7 billion people. Wood is not 100% carbon and a wood house is ~30 tons of wood. But, there is not a house per person and people don't build new houses every few years.
Biochar can be continuously applied on fields to improve degraded soils, and its production from woody biomass is energy positive and inexpensive.
I say this because the volumes of CO2 capture necessary for the two degree scenario (that we all just committed to in Paris) are so beyond the scale of almost anything we manufacture that it's not even funny.
We're talking thousands of Hoover dams full of liquid CO2 that has to be captured, transported and stored every year.
It's just that doing something impossible is tricky.
Time-to-rot varies, from 50-100 years for a spruce, 200-300 for a pine.
I've witnessed downed redwoods myself, over the course of four, nearly five decades, which have failed to decompose even in highly damp conditions.
Bogs and swamps are also underappreciated CO₂ sinks.
I'm sure most people are picturing factories here, but using low/appropriate tech as well is essential. Building soil and woody biomass can absorb enormous amounts of carbon.
The question essentially becomes, how much biomass per hectare are we talking about? Absorbing the 350 teratonnes of human emitted carbon [1] over the 11.7 billion hectares of Earth's non-tundra land surface [2] works out to 30 tonnes of carbon per hectare. If you exclude deserts it's 42 tonnes per hectare, but the technology already exists to successfully "green" deserts.
That's 30 trees per hectare, at 1 tonne per tree.[3] Or 3 kg per square meter of soil carbon, the equivalent of 25 cm of topsoil Soil carbon is stored up to 40 meters down by deep rooted plants, so in practice this isn't a problem. [4]
Most of our land management is via agricultural, so agricultural reform is the only lever long enough to make a dent. Practically this means switching from soil destroying tillage to soil building cover crops, long-distance imported fertilizer to in-situ fertility produced by soil organisms[5], and ecologically unstable monocultures to resiliant polyculture and agroforestry systems.
If you run the numbers trying to use factories alone the cost is astronomical. It's larger* than the world's global energy infrastructure, because thermodynamics is working against you.
An overhaul of agriculture using modern environmental biology is the only thing with a lever long enough to make the numbers close. Plus it simultaneously solves the existential risks posed by our laughably unsustainable food production system and the collapse of ecosystem services by habitat destruction.[6]
[1] http://petrolog.typepad.com/climate_change/2010/01/cumulativ...
[2] http://cnx.org/contents/TWFXbERo@1/The-main-biomes
[3] http://cabiblog.typepad.com/hand_picked/2011/06/ever-wondere...
[4] http://www.soilquality.org.au/factsheets/organic-carbon
[5] https://www.youtube.com/watch?v=x2H60ritjag
[6] http://unctad.org/en/PublicationsLibrary/ditcted2012d3_en.pd... [PDF, 5.2MB]
And that was the first time I ever saw anyone throwing a number for how many tonnes we are really talking about in any debate I have seen either here or on AT.
Congrats! More numbers, less politics!
(Not saying it is correct, I haven't verified, -but unlike "celebrity X says we should do something now" this is something that can be measured and discussed rationally.)
The power plant also produces waste heat which presumably is useful for the reaction. So a combined plant that produces electricity and CNTs with zero carbon emissions is likely more efficient than using electricity to a) heat the whole thing b) pull CO2 out of the air c) run electrolysis.
Disposal of it could be just as costly as Asbestos with just as adverse side effects.
I fully understand that some people getting cancer is less of a problem than our planet becoming uninhabitable, but it most certainly can't be swept under the carpet and forgotten about.
http://www.ncbi.nlm.nih.gov/pubmed/23751780 http://www.ncbi.nlm.nih.gov/pubmed/16686422 http://www.ncbi.nlm.nih.gov/pubmed/20795897
We already do that. It's called food. Pretty much all carbon you see on your plate came from CO2 floating in the atmosphere.
And, BTW, if we remove all CO2 from the atmosphere to make cars, batteries and bridges, we'll eventually realize those things are not very nutritious.
CH4 + O2 --> C + 2 H2O + energy
Also, I'd assume that if many power plants start to do this, then the nanotubes price will drop almost to the level of soot. (Would it be much cheaper to just make soot instead of nanotubes?) But they say that the energy production will drop only 10%, so this may make sense with some carbon taxes.
But I really don't like that in the research article they propose to use this in coal plants. They use a complex scheme, (with additional solar panels?), but the global chemical reaction doesn't make sense. They start with coal that is essentially C and the final product is nanotubes that are essentially C, so there is very little room to extract energy.
Wouldn't a substantial pile of such tubes be a serious fire hazard? Aren't they essentially the carbon version of steel wool, ie much more flammable than solid carbon?
If they are flammable, even explosive, nobody has any protocol that could make storage of such volumes safe.
Dumb question for a non-engineer: couldn't they feed them back through the power plant again?
"They found that the concept is economically feasible and even improves the power plants' energy efficiency."
If that's true, and assuming the CNTs can be sold, sequestered, re-burned, or otherwise disposed of in a way that doesn't ... "exploit" their über-asbestos aspect, I'd think it worth doing on that basis alone.
The new extended electricity plant that produces nanotubes and burn them have the same maximal theoretical electricity output than a traditional electricity plant, but if the "energy efficiency" were true then the new method would produce more electricity.
The traditional method is something like burning the hell of the methane, use the heat to produce electricity and release all the CO2 to the atmosphere
The new method would be, bun the hell of the methane, use the heat to produce electricity, use the CO2 to produce LiCO3, use part of the electricity to produce nanotubes and LiO, burn the nanotubes and use this additional heat to produce electricity and release the CO2 to the atmosphere. The calculations are more complicated because the fumes have different temperatures, and other technical details.
But for me it's unbelievable that an indirect method that transform the CO2 to nanotubes and burns them ads "energy efficiency". I'd guess a 30% energy lost in each step.
That said, increasing the concentration might not be smart anyways, -I don't know, at this point I'm not really sure. (I used to be very skeptic, now I'm starting to think it might be correct and the proponents just don't get PR.)
Do you or do you not believe in the link between the burning of fossil fuels and climate change? If you do not, I am not going to get into a theological debate with a believer.
?
It matters nothing for the chemical properties of CO2.
> If you do not, I am not going to get into a theological debate with a believer.
I am very much a believer, and for technical stuff I believe in experiments, measurements etc : )
"The thermodynamic enthalpy available per CO2 emitted from carbon combustion (−394 kJ/mole) is less than that from methane (−890 kJ/mole) combustion. Coal, compared to natural gas, combustion will generate less excess heat per transformable CO2 to drive CNF [carbon nanofiber] and CNT [copper nanotube] production product is retained within the system at (the electrolysis chamber temperature of) 750 °C, and hence under normal circumstances while a CC [combined-cycle natural gas] CNF plant can co-produce electricity and CNFs, a coal CNF plant will produce only value-added carbon nanotubes, and not surplus electricity."
Annotations in brackets are mine.
Wait what? Where is the electrical energy coming from if not from bringing solid carbon into a lower energy state by oxidising it and releasing the energy difference as heat? If you want to reverse that process you will with certainty have to invest more energy to account for all the losses. At which point this isn't a power plant anymore. Am I missing something here?
Of course you're not generating as much power as just burning the methane completely.
[1] http://www.engineeringtoolbox.com/co2-emission-fuels-d_1085....
[1] https://en.wikipedia.org/wiki/Combined_cycle#Efficiency_of_C...
Dose-dependent mesothelioma induction by intraperitoneal administration of multi-wall carbon nanotubes in p53 heterozygous mice
" Here, we report a dose-response study; three groups of p53 heterozygous mice (n = 20) were given a single intraperitoneal injection of 300 μg/mouse of μm-MWCNT (corresponding to 1 × 108 fibers), 30 μg/mouse (1 × 107) or 3 μg/mouse (1 × 106), respectively, and observed for up to 1 year. The cumulative incidence of mesotheliomas was 19/20, 17/20 and 5/20, respectively." [1]
[1]http://onlinelibrary.wiley.com/doi/10.1111/j.1349-7006.2012....
There is NO scarcity of carbon as an input in industrial processes. so producing it through the MOST inefficient means , just like making FUEL OUT OF ETHANOL , is not just unprofitable and dumb, but environmentally destructive and stupid.
capturing carbon is just making it more expensive to burn more carbon based fuel. capturing carbon means you are getting a lower EROI on the input energy. so you are actually winding up getting a more carbon intensive energy production as a result Albeit ----some of that carbon is going to be 'captured'. BUT this means the more carbon capture you achieve, the more carbon intensive your energy source!!!!! moral hazard anyone?
the support for carbon capture amongst the greenies is one of the best examples of internal inconsistency and thoughtlessness amongst the greens. the total rejection of nuclear power on any and all terms, is the another.
but let's get on with it. consider that all this 'captured carbon' will just be magically stored underground or somewhere else it won't escape for a 100 million years. MASSIVE VOLUMES in the atmosphere, cheaply and easily 'CAPTURED' and now of course, we assume it can all be stored perfectly. just like nuclear waste right!?
no. that was sarcasm. c02 sequestration is the biggest joke of all. despite the nonexistence of effective sequestration methods ( which all COST ENERGY, and are thus more carbon intensive ) ------why not assume it already exist.
ok what then, consider that within 100 years, any given earthquake let alone the basic erosion of nature will eventually lead to this carbon somehow coming back to the atmosphere one way or another.
so now , the final piece of stupidity is introduced, let's take the carbon and use it for industrial production instead of sequestering it. yes , PERFECT!!!!! LET'S INVENT NEW THINGS THAT DON'T EXIST AND ARE UNPROFITEABLE EVEN IF THEY DID AND USE THE MOST EXPENSIVE THEORETICAL SOURCE OF INPUTS OF CARBON TO MAKE THEM.
this is how sovietized economies reason, based on a goal centric output, rejecting ALL COMMON SENSE about investment to achieve the perfect recipe for optimal levels of destructive malinvestment.
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let me break it down for you liberals. the only effective way to sequester carbon is to plant trees, or otherwise encourage nature to run her own course (perhaps by stopping clearcutting trees to begin with) , because natures' course naturally consumes oxygen and sequesters carbon by way of...THE CARBON CYCLE!. seeding the ocean with iron for algea has not worked because our science is lacking in the area. we know SO LITTLE about the ocean, including to what extent it controls our atmosphere. YES, every year a whole new ton of research comes out about the oceans previously unknown influences on the atmosphere. why is this? because it is deep and huge. and so much of the ocean has not been subject to study without physical penetration in many different simultaneous locations ( like the worlds biggest scientific gang bang ) . Only now are we even beginning to understand ocean currents below the surface of the ocean ( where 99.999 percent of the ocean's water exists )
as for carbon, capturing it from smokestacks is just stupid. It is uneconomical let alone more carbon intensive. please by all means continue to pursue your interests in renewable energies. but stop being dumb. carbon capture for the sake of smoke stack 'cleansing' is a cruel joke.