Scientists say we’re on the cusp of a carbon dioxide–recycling revolution

http://www.sciencemag.org/news/2018/03/scientists-say-we-re-cusp-carbon-dioxide-recycling-revolution

by masonic • 8 years ago

201 125 8 years ago

sciencemag.org

88e282102ae2e5b• 8 years ago

it’s really a matter of maybe 5 to 10 years.

So...not holding my breath.

pmontra2• 8 years ago

If they make estimates like us, software developers, this is likely 50 to 100 years :-)

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...

tehwalrus• 8 years ago

They also seem to preserve the number of total CO2 molecules around.

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.

tytytytytytytyt• 8 years ago

We'll have safe self-driving cars and a cure for cancer then, too.

And we'll regrow our teeth with stem cells.

chopin• 8 years ago

So, I am burning some carbo hydrates to water and carbon dioxide and then... generate carbo hydrates out of it? Mmmh, something doesn't sound right.

notabee2• 8 years ago

That's right, it doesn't sound right because you're making the assumption that the energy to do this would come from non-renewable energy sources. The value of this technology is to sequester carbon or convert energy output that's variable over time from renewables to a more consistent form of energy without digging more carbon out of the ground.

sandworm1012• 8 years ago

No. Co2 is a very low-energy chemical. Converting it into nearly anything else will take far more energy than other sources. This is possible, but not economical without massive insentives. Maybe once all the oil is truly gone will this become a thing.

mkempe6• 8 years ago

Are you aware of photosynthesis? free use of plentiful energy? do you have something against the kingdom of plants?

eloff5• 8 years ago

Which requires massive amounts of energy. It's not particularly efficient.

kaslai• 8 years ago

In photosynthesis, the carbon dioxide is merely a source of carbon. The energy that fuels the reaction comes from light.

dang• 8 years ago

Would you please stop posting uncivil and/or unsubstantive comments to HN?

https://news.ycombinator.com/newsguidelines.html

rossdavidh• 8 years ago

I would need to see something about how much electricity they're talking about here. I am not seeing a way to do this with less than the electricity you got from burning the fossil fuels in the first place (and inevitably, somewhat more). The only way I could see this being useful is if at some point in the future we are no longer burning fossil fuels for electricity, and we want to get the CO2 back out of the atmosphere. But, you know, turning them into living trees is not a bad way to do that, and it already exists...

davidp• 8 years ago

You're mostly right, except that trees are now understood to not be a great way to sequester carbon: They eventually grow old and die, and the carbon in them is released as they rot. Over (non-geological) time trees are net carbon neutral.

eloff5• 8 years ago

I hear that mentioned a lot. But there are some important considerations. Taking previously unforrested land and converting it to forests will sequester carbon for as long as that condition holds. Planting trees and either letting them grow into old growth forests or using them for lumber can sequester carbon for centuries. Don't underestimate the value of buying time to transition to clean energy and develop more advanced technology.

njarboe• 8 years ago

Many tree species live for thousands of years, most for hundreds. Growing them will sequester a lot of carbon. Plus the soils in mature forest will sequester more. The amount of carbon you could sequester in a mature redwood, or fir forest is huge. In climates where these tree wont grow, oaks often will and can capture a lot of carbon and live for millennia. I would be interested on where you got the idea that trees are not a good way to sequester carbon (ref to a paper?).

danieltillett3• 8 years ago

The key is to turn the trees into biochar and put it back into the soil.

usrusr3• 8 years ago

Not even over geological timescales anymore: from what I picked up in discussions (I'm not an expert), the majority fossil carbon was trapped at a time when trees had a defensive "technology advantage" over fungi so big that they would resist all rotting even after death because nothing the capability to "digest" wood had not been evolved yet. That way they could just accumulate until getting buried by those incredibly slow geological processes.

DrScump• 8 years ago

If facilities for this process can use "waste" electricity (e.g. more solar than is being consumed on the grid and/or off-peak surplus electricity from other sources), then it makes economic sense.

throwaway5752• 8 years ago

For those that saying this will take energy, this is a means of storing and concentrating enormous by diffuse renewable energy resources. Of course it's highly endergonic, but that's not the point.

eloff5• 8 years ago

How can you burn fossil fuels to produce electricity, to use to turn the combustion byproducts back into fuel at any reasonable level of efficiency? Some people here are saying the electricity doesn't matter, because it is from renewable sources - but then you could just shut down that dirty coal plant and use the renewable energy directly. Something doesn't add up here.

a3n• 8 years ago

The CO2 is already there, now. Might as well use it.

jcranberry• 8 years ago

I think the worry is that it might cost more energy to process the CO2 than it actually produces. In which case the energy would be more of a byproduct of removing the CO2 from the atmosphere, I guess?

allthenews• 8 years ago

The advantage of fossil fuels in this case is energy storage density, and potentially longer engine life than that afforded by modern batteries.

derekp7• 8 years ago

The renewable power source for the electricity isn't close enough to where it is needed (hydro-electric), or not stable enough (wind, solar). And the fuel produced can be used for applications other than power generation. And used as a storage medium to even out the bumps in solar/wind.

For that last category, this process needs to be more effective than battery storage.

ttul• 8 years ago

And if there is a price on carbon pollution that is high enough, that would help make the case.

kragen6• 8 years ago

Basically this is a reasonable idea for transport fuels. Sunlight gives you 1000 W/m², or 160 W/m² at 16% photovoltaic efficiency. A Boeing 777 has a surface area on top of something under 1000 m², and so if you cover it with solar panels, you get 160 kW when the sun is shining directly on it. But its engines produce somewhere between 700 and 1100 kN at a cruising speed of 900 kph, or 250 m/s, which if you work it out means it would need 175–275 MW if the engines are 100% efficient, a bit over 1000 times what it can gather from the sun. (A bit less since it's not running the engines at full power when it's cruising, but a lot more when you take into account that the engines are quite inefficient.)

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.

entee2• 8 years ago

This is an excellent point, however even so you'd still have another problem. Let's say this all works great, and we get to the prices that make it feasible. You're still just adding one go around to the carbon cycle. The fuel you burn at the power plant once gets back converted to fuel once, then turns into CO2 that you can't recover when coming out the back of a 777.

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.

simonebrunozzi2• 8 years ago

This might be an off-tangent, but comments like yours are the main reason why I so much love HN, and why it has become more than 1/3rd of the time I spend on the Internet.

Thanks for investing the time to write this. You gave me so much.

mrfusion• 8 years ago

From my math I got something around 1 square kilometer of solar panels to power a jet.

Basically one square kilometer is 1 million square meters times 160w/sq meter is 160mw.

mkempe6• 8 years ago

As the French say: Avec des "si" on mettrait Paris en bouteille. (With some "if" one could put Paris inside a bottle.)

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.

danieltillett3• 8 years ago

The only problem with this analysis is the 777 (and all modern aircraft) is designed around a fuel cost of a certain price. Moving to higher cost renewable energy would change the whole design of passenger aircraft.

erikpukinskis• 8 years ago

You can put the solar panel in space and beam concentraded light to the plane in laser form and get much higher watts per sq ft.

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.

agumonkey• 8 years ago

What about a 50 to 100 passenger, large triangle glider shape PV coated. Medious speed, light motors, no duel and take off energy provided from a ground propeller ?

Retric• 8 years ago

You numbers are off. 45,220 US gal gives 14,260 km range at 905 km/h + emergency reserve. ~= 16 hours of flight time 2830 gal / hour of fuel used. 37 kWh per gallon * ~.40 effecency * 2830 ~42,000kWh.

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.

aoner• 8 years ago

I was recently thinking about this problem. Why not beam energy to planes (as also mentioned in comments). We could create a network of zeppelins that use/store wind and solar energy and beam them towards planes. As an extra bonus these zeppelins can be used for a multitude of things like internet and weather stations.

ebbv3• 8 years ago

Your suspicion is correct. This is a film flam. At best this is an extremely inefficient way to store energy.

skybrian• 8 years ago

This is for soaking up renewable energy that either isn't connected to the grid yet, or is being generated at the wrong time. Since there's no fuel cost for wind or solar, you might as well do something with it. Anyone willing to buy electricity at inconvenient places or times will help make renewable energy generation more profitable, so more will be built.

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.

eloff5• 8 years ago

That makes sense, I was struggling to grasp how it could be economical.

Gravityloss3• 8 years ago

Demand elasticity. We are still really far from reasonable deployment.

Talking to a friend who worked for a power utility here, it's a very foreign concept. Some room for disruption there.

Gravityloss3• 8 years ago

For this you would need to store the CO2. For each ton of coal burned you generate about 3 tons of CO2. At atmospheric pressure thats 1500 cubic meters. A small 200 MW power plant could burn 80 tonnes per hour. Thats 120 000 cubic meters. That is a building 12 m high and 100 m square.

I guess everything is possible given the right subsidies...

tfha• 8 years ago

Bitcoin mining unfortunately is typically useless for sucking up spare electricity. The hardware is too expensive, unless it's running 85%+ uptime, you will not make back your initial hardware purchase.

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.

neltnerb3• 8 years ago

Yeah, I had to write a proposal for a carbon capture project. It was really hard to make it make any sense from a systems perspective.

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.

myrryr• 8 years ago

Time... It is all about when you want to use the electricity.

philwelch• 8 years ago

This could be useful for developing countries, if the following supply chain became feasible:

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.

sametmax• 8 years ago

Because we have convenient gas station network and a lot of combustion engines already. That also have the benefit of a huge range and instant top up.

A tech to transition would be a good thing.

empath75• 8 years ago

If this actually works and global warming gets bad enough, we could build a bunch of nuclear plants for this, if nothing else.

ynniv• 8 years ago

Rechargeable batteries aren’t currently as mass or volume efficient as these chemical forms.

https://en.m.wikipedia.org/wiki/Energy_density#/media/File%3...

TheCoelacanth• 8 years ago

If you apply this idea, fossil fuels are no longer a source of energy, they are now a way of storing and transporting energy. You could have a bunch of solar panels in Arizona where there is a lot of sun and cheap land and then ship the fuel somewhere else where solar is less efficient.

fyi1183• 8 years ago

They are also no longer fossil fuels, just chemically equivalent or at least similar hydrocarbons.

I wonder if language will eventually change to reflect that.

SomewhatLikely• 8 years ago

How would this compare to the approaches attempting to use algae?

titojankowski2• 8 years ago

YC’s new "Carbon Removal Technologies" RFS: https://www.ycombinator.com/rfs/#carbon

Index of 82 startups and projects mining carbon from the air: http://airminers.org

(disclosure: airminers.org co-creator)

meganibla2• 8 years ago

Enter climate change caused by too little carbon dioxide in the atmosphere

TheAdamAndChe• 8 years ago

Sinusoidal homeostasis around a set point is far superior to exponential growth in one direction.

meganibla2• 8 years ago

Surprisingly, I find nothing to disagree with in your strawman argument ;p

drewbuschhorn4• 8 years ago

As a former chemist involved in the field, no, we're really not.

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.

lambdadmitry• 8 years ago

I tried to find such a review, but failed. Can you please provide a bit more pointers?

ianai5• 8 years ago

I’m curious as well.

drewbuschhorn4• 8 years ago

"Co2 fixation" / capture is the starting keyword you want, though "coalgas" frequently turns up good fundemental work from the 80s. https://pubs.acs.org/journal/jacsat#/action/doMobileSearch?&...

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.

neltnerb3• 8 years ago

Not to mention that basically all the collected data and goals are centered on flue gas with high CO2 concentrations.

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!

drewbuschhorn4• 8 years ago

Yep, saying your going to gassify crude oil and then recycle the co2 is basically like saying your going to unspill milk. The only point in the thing's favor is that there's tons floating around already.

masonic• 8 years ago

   flue gas with high CO2 concentrations

Wouldn't such a technology be useful in "scrubbing" exhaust from electrical plants, at least?

08-15• 8 years ago

But why is anyone cheerleading for this pointless technology? Why bother with capturing a trace gas from the atmosphere?

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.

drewbuschhorn4• 8 years ago

If you can beat the HB and Ostwald processes, I say go for it. I think the idea behind carbon capture from serious people is: 1. That it should be solar powered / low energy 2. Catalyst cheap as dirt, so that 3. CO2 in the air is free, so you'd basically have the plant start up costs and then the rest is free money. Also envy of the plants for making it look easy.

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.

noddy1• 8 years ago

If this could be applied to making palm oil substitute, that might be the only thing that can stop deforestation of indonesia/borneo/PNG

coldtea• 8 years ago

In terms of how close we are to industrial impact—it’s really a matter of maybe 5 to 10 years.

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.

Scientists say we’re on the cusp of a carbon dioxide–recycling revolution

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