Scientists say we’re on the cusp of a carbon dioxide–recycling revolution
sciencemag.org
sciencemag.org
Reading the Joule letter referenced, it's basically just cheerleading, which does need to happen every few years to keep people going.
Last I was involved, all the major non-nanosurface based catalysts either had horrible separability or cycles in the 1k range.
Commercial catalysts frequently have cycles in the billions. When someone cracks this nut, they'll make money hand over fist, but we're not there yet.
JACS has a review article every few years on this for anyone with high school chem and an actual interest.
For reviews specifically: https://pubs.acs.org/journal/jacsat#/action/doMobileSearch?&...
See also Royal Society: http://pubs.rsc.org/en/content/articlelanding/2014/cs/c3cs60... . I can try and do a better filter job if people want, I think jacs keyword matching has managed to get worse.
It's contradictory, if you have isolated fossil power and for some reason have excess renewable power co-located to convert the waste back to chemicals, then just turn off the fossil power... unless this is a load balancing play, which it is not ever going to be good for.
And the original oil and coal is better for converting to chemicals anyway!
flue gas with high CO2 concentrations
This is a rube goldberg machine, taking high value hydrocarbons that could be converted to commodity and fine chemicals and instead burning them and taking the released carbon and... putting it back together? It's not even a very efficient perpetual motion machine.
It seems to me that stranded clean energy would be better spent making ammonia. We've been making ammonia from air and natural gas for a hundred years, we know how to make it from air, water and electricity. It is easy to transport, the market for it is huge, and making ammonia "captures" CO2 by replacing a different plant that would have emitted it.
If we really wanted to take CO2 back out of the atmosphere (and we don't need to even think about that as long as there a coal, oil and gas burning power plants everywhere), we should simply grind up silicate rocks. Doing so makes reasonably good soil that may not even need fertilizer (other than ammonia), and once plants grow in it, it with weather rather quickly, thereby permanently sequestering CO2.
Seriously, why bother with CO2 capture from air? Looks like a fool's errand to me.
Anybody saying it would make a dent on the global CO2 consumption is just spouting grant proposal talk, for the entropic reasons everyone else is talking about on this thread, or else is a crazy geoengineering nut.
That being said, if you dig into it, most groups that publish papers on the subject do it as an interesting sideline / something to grab some low hanging attention. It's really just checked out as a side effect of other things, like being able to functionalize hard to move chemical groups.
One of my Fe compounds could capture CO2 gas and convert it into oxalic acid ( H2O + 2CO2 =cat=> H2(CO2)2 + 1/2O2 ) ... almost a whole 50 cycles before it got poisoned by its own O2 production (the compound burst into flames in air, btw). But it could also functionalize one of the lowest energy N bonds known, and in a selective fashion. It was floated as a means for a two step synthesis of some kidney drug, but ... the bursting into flame thing.
You wouldn't try to beat those processes. You'd run them as usual but with hydrogen from water electrolysis instead of from steam-reformed fossil resources. Of course both levelized cost of renewable electricity and cost of running electrolyzers at low duty cycle need to decline significantly more before that could compete with the current status quo of cheap natural gas and no CO2 emission taxes.
Renewable ammonia made this way still seems more plausible for near-future commercialization than making liquid hydrocarbon fuels from renewable electricity and atmospheric CO2. Which is admittedly faint praise. The advantage that might eventually be significant is that it's easier to ship ammonia or simple derivatives of it from some remote but renewable-energy-resource-rich place, like windy islands, than to build electricity transmission lines.
I've always believed this is why people start a career in chemistry but alas as you point out, it's not why people pay anyone (except DARPA) to carry on.
Or do you believe that this particular interglacial will, somehow, never end?
Or do you have evidence for other primary cyclical causes of ice ages, interglacials, and glaciations?
I’m pretty sure that’s not a question. If they were claiming it would generate more energy than it took, this article would have been about a perpetual motion machine.
For that last category, this process needs to be more effective than battery storage.
(And remember that 30% is only on the recovery side, you’d have to factor in any inefficiencies on the storage side before getting a final efficiency number to compare against other means such as batteries.)
High efficiency gas plants are reaching 60%, and it gets better when you have consumers for waste heat who would otherwise be burning fossils just for heating. Maybe you are be confusing the numbers with well-to-wheels efficiency of electric cars?
There are ways you can design the plane to use less power, and Solar Impulse 2 demonstrated that it is in fact possible to fly on solar power alone, but Solar Impulse 2 also took 23 days to go around the world, has a maximum speed of 140 km/h, and has a maximum passenger capacity of 1, rather than a few hundred. Design compromises like these are necessary to lower the power intensity of flight to a solar-feasible level. So, it's likely that liquid-fueled aircraft (the 777 burns kerosene) will continue to have substantial advantages over solar aircraft for the foreseeable future.
The obvious solution is to use some 10⁸ m² of area on the ground — something like a 10 km by 10 km square for each 777 in flight — to generate electricity to produce the liquid fuels for the liquid-fueled aircraft. That sounds like a ridiculous thing to do, building a city-sized solar plant for a single airplane, and today it would be — the photovoltaic modules would cost US$5 billion and installing them would cost another US$5 billion, for a total of US$10 billion. The entire Boeing 777 development cost was only US$5 billion, and each plane sells for US$300M or so. So the cost of the power plant would be something like 30× as high as the cost of the airplanes themselves.
From an exponential point of view, though, that's only 5 doublings. If the price-performance of photovoltaic modules improves by a factor of 2 five times, the power plant falls to the cost of the plane. If PV modules continue dropping in price by 30% per year, as they have been for the last four years or so, that crossover happens in 2028; if they continue dropping in price by 20% per year, as they have been over a somewhat longer period, it happens in 2033. It's only in a scenario where PV modules effectively stop dropping in price where this remains a ridiculous idea.
The same logic applies, but in a weaker form and a nearer crossover, for other challenging transport fuel uses such as ships and trucking.
The only way this technology gets to the point where it's net carbon neutral or negative is if it can process the highly dilute CO2 coming out of the free air efficiently rather than the highly concentrated CO2 coming out of a power plant. I have a sense that the dilute case is quite a bit more challenging to make work at scale and efficiently.
So, if 100% of diesel were carbon that gets burned, you would get 3.67 tons of CO2. That leaves room for incomplete combustion and for other things than carbon (hydrogen, nitrogen, sulphur, etc).
You mean like a tree does, or corn for ethanol production, or...?
Thanks for investing the time to write this. You gave me so much.
Free online, and a the best seller physical book in the field: https://www.withouthotair.com/
The book is brilliant, we need more people like him.
His comments about scale are true, but also aren't entirely complete. You probably can't replace the entire economy we have with lower intensity sources of energy without also having to reduce energy consumption, is his key argument.
But, striking out the worst ones with the best ones we can invent is still interesting.
It's a good read, but it's not holy canon. Parts are contestable and parts are highly contextual and parts are conjecture. Actually.. that makes it quite like holy canon.
https://www.carboncommentary.com/blog/2017/3/30/l6qcqgoedse1...
Would love a new commit of some sort :)
They are indeed now being deployed, as are significantly better generators per turbine. His methodology is sound. His specific numbers are going to have to be adjusted. His overall polemic will probably stand (that high energy density sources like nuclear make more sense but are political)
Basically one square kilometer is 1 million square meters times 160w/sq meter is 160mw.
In nevada, you have about 3600 sun hours per year, so about 40% of all hours.
So ignoring transmission losses, "reverse fuel cell efficiency", wouldn't we expect an average of 64 MW from each square kilometer of solar panels?
All in the name of being opposed to CO2, an essential nutrient of plants and a by-product of industrial/modern productive activity. Billions of humans are and remain alive today thanks to fossil fuel.
No fuel weight should be an advantage. Is there any disadvantage? Would transmission loss be too high? You’d still need batteries for takeoff/landing. But you could charge them at cruising altitude.
2) Too many easily broken parts and too little fall-back mechanisms. (What do you do if it fails? You have to be able to reach the nearest airport, which, over the big oceans, will be near-impossible without carrying at least half-a-journey full of energy anyway.) (Good luck getting something like this through certification..)
3) NIMBYs will try to stop you from darkening their skies. If you want to take the energy from next to earth, there will be additional energy influx (and you can put a global-warming equivalent on that).
There are many more if I think for more than 10s.
Lasers are an option but they're not very efficient, and blocked by clouds. Instead we can use microwaves. The watts per square foot would be just a little higher than sunlight, which is good for safety anyway. Total efficiency from satellite to grid would be about 50%, which isn't bad since it keeps running at full strength at night and on cloudy days, and sunlight is 30% stronger in space to start with.
NASA's monolithic design from the 1970s would have been absurdly expensive even if launch were free. Some recent designs are completely different. The book focuses on SPS-Alpha, a modular design made of many thousands of identical components of eight different types, each only a meter or two wide, which self-assemble in orbit. There's no single point of failure, and the components are cheap since you mass-produce them.
The book estimates a retail electricity price of $0.15/kWh. I plugged in the extremely low launch cost SpaceX is claiming for the BFR, and got a price of $0.045/kWh. That would decrease further over time. U.S. national average is about ten cents.
[1] https://www.amazon.com/Case-Space-Solar-Power-ebook/dp/B00HN...
[1] Peter Ongaro, Leopold Summerer; "Peter Glaser Lecture, Space and a Sustainable 21st Century Energy System"; (57th International Austronautical Congress, 2006)
Surely this whole idea has been discussed before but I don't recall ever coming across it before.
40% solar panels are available but 23% are low cost. So 230 kWh or 400kWh which means 100x to 180x not 1000x Before considering fuel vs panel weight.
PS: At the other extreme solar can hit 2.4kW/kg which would be worth installing on aircraft to reduce APU fuel consumption.
There are lots of potential competitors, though: other kinds of energy storage (such as charging a battery), industrial users that can run in the off hours, or maybe generating Bitcoin. It's probably too soon to say whether this technology will win.
Buying electricity at a low price and selling it at a different time or place at a higher price is basically a form of arbitrage. Hopefully energy storage will become more efficient at getting electricity to customers when they need it, so they can outbid things like Bitcoin mining.
Talking to a friend who worked for a power utility here, it's a very foreign concept. Some room for disruption there.
I guess everything is possible given the right subsidies...
We can thank Moore's law for that. Bitcoin miners go obsolete every time a new generation of silicon hits maturity. 85% uptime requirement will drop substantially after Moore's law tapers off.
Except that Moore's law has tapered off substantially. The latest 10nm process node is 3 years late[0], and the next one will probably be substantially more difficult than that.
[0] https://www.anandtech.com/show/12436/intel-10nm-dualcore-can...
I conclude that talking about using it to reduce emissions from fossil plants is idiocy only useful for PR. You are always better off not burning the carbon in the first place and just getting the electricity from another source.
The only even remotely compelling case is that it lets the plant respond faster to load by dumping excess electricity into chemicals. And even there, it's not the best solution, it's probably better handled by the way we do it now with load-following plants.
I think the researchers know that, they talked about using renewable power for it. But I'm sure their estimates are also based on consuming coal flue gas because they have to goose the numbers to make the CO2 cheap and concentrated enough to make any sense. So my assumption with basically any of these is that they're setting up a paradoxical situation -- assume that we're using fossil power plants for the CO2, but getting the electricity/hydrogen from renewables. That way the chemicals look close to free.
But if we're still generating electricity with the fossil plant, it will always be better to just not use the plant from a CO2 and systems efficiency perspective and to instead build more renewable generation to make up the difference.
1. Rich country builds nuclear reactors to generate power 2. Rich country uses nuclear power to synthesize hydrocarbons for export 3. Developing country imports hydrocarbons for domestic energy needs
Developing countries don’t have the resources to build nuclear reactors, and we might not want to export the nuclear technology anyway, but we can export the actual energy this way.
A tech to transition would be a good thing.
https://en.m.wikipedia.org/wiki/Energy_density#/media/File%3...
I wonder if language will eventually change to reflect that.
I know I’d love to see homes built out of wood more often, as well.
A few people have suggested doing exactly this with nitrogen fixing trees like Casuarina sp.
Index of 82 startups and projects mining carbon from the air: http://airminers.org
(disclosure: airminers.org co-creator)
Solar panels can reduce carbon emmissions, but to actually take the carbon out of the air and keep it out means converting it into something akin to coal. This takes massive power, which must in turn come from a green source.
Further, how do you explain the Carboniferous CO2-fixation that started with CO2 at 4,500 ppm and ended down below 210 ppm?
Contrary to your claims that only bogs or permafrost could keep plant-fixed carbon in the long run, phytoplankton absorb carbon in vast quantities, and when they sink their accumulation in sea floors for millions of years is the primary origin story of oil and coal.
Scientists say that plant life has exerted and continues to exert "massive power" over geological eras. Are they in error?
So...not holding my breath.
The real revolution is that we won't have to drill oil and everybody will be able to make fuel from the air anywhere in the world. The economic and political consequences will be huge.
However this process doesn't seem able to reduce greenhouse gases in the air. They say the fuel they get is carbon monoxide, methane, ethylene.
Methane burns like this: CH4 + 4 O2 = 2 H2O + CO2. The process to create that methane from CO2 probably starts with one molecule of CO2 because there is only one C in CH4, so we had one CO2 and we end up with one CO2.
Carbon monoxide burns like 2 CO + O2 = 2 CO2.
Ethylene burns like C2H4 + 3 O2 = 2 CO2 + 2 H2O.
They also seem to preserve the number of total CO2 molecules around.
To really reduce the CO2 in the air we should find a way to turn it into stone, something like this plant in Iceland https://qz.com/1100221/the-worlds-first-negative-emissions-p...
Of course, they are chemical reactions. Did you think they would destroy atoms?
The idea here is to make renewable hydrocarbons: when you burn them, they are only putting CO2 that came from the atmosphere back, not releasing new CO2 from fossil fuels.
It assumes that you power this fuel-generator with renewable energy, of course.
Obviously not, that would be far too much energetic :-)
If the goal is removing CO2 the reaction should combine some C into something that doesn't burn, but that's not going to happen if the goal is creating fuel.
And we'll regrow our teeth with stem cells.
No matter how old you are when you read that, be prepared to continue to listen that the same technology is "5 to 10 years" away for the rest of your life.