You also have to remember the costs of capturing CO2, which is best done at the points of emission, and transporting the CO2 to the (usually far away) storage site.

OTOH, the total cost (not just for sequestration) is about $100, maybe a bit more, in most estimates.

For reference, a gallon of gas produces 20 pounds of CO2, so $100/ton equals $1/gallon of gasoline. That's roughly what you'd have to increase gasoline price by to fund CO2 capture, transport and storage. (This neglects that the capture part is neigh-on impossible.)

For electricity, to compensate for the average US CO2 emissions per kWh (~1.2 lbs/kWh), you'd have to increase the price by about 6 cents per kWh.

To do CCS for both gasoline and electricity consumption, the average US family would have to pay (order of magnitude) 1000 x $1 + 12000 x $0.06 = $1720. That would compensate for about half the family's CO2 emissions. The remaining half is dominated by emissions from the food we eat, the stuff we buy and from having fun.

Edit: this should say $1720 per year.

> Additionally, it's important that people realize that CO2 production is in tons of CO2 per year. Tree offsets are a one-time deal, since when trees die they release CO2, and when new ones are born they absorb that CO2 again. After they've been planted, forests are generally carbon neutral. That's why we can't "just plant trees": we'd have to be continuously planting new trees. The Earth is only 8% arable land, much of which already has stuff on it, or is undesirable for one reason or another. We'd run out of space pretty fast. Trees are good for other reasons: preventing climate change (different from global warming), preserving species diversity, being nice to look at, etc etc.

You misunderstand the purpose of trees. They're basically solar powered, organic carbon sequestration devices that happen to run for free. If we ever run out of space to plant trees, we can just cut some down, reduce it down to charcoal and bury it back into the ground which conveniently leaves a readily accessible fossil fuel source for our ancestors in the case of civilizational collapse.

But we're still a long way away from running out of room to plant trees. We're still desperately trying to plant enough trees to stop the encroaching of the Sahara and there's vague, futuristic plans to try and turn the entire Sahara into a forest. Similarly, China is desperately planting trees to stop the encroachment of the Gobi.

Reducing trees to charcoal is not cost effective. It releases a ton of carbon dioxide by itself anyway. But it also doesn't make sense that we would plant trees, turn them into charcoal, and then bury that. This is insanely expensive and by the time you've got charcoal, you might as well burn that, too, rather than burying it and then digging up more coal to burn.

The whole reason we had the second stage of the Industrial Revolution is that if you use trees instead of mining then you're limited in energy by the acreage you can devote to trees and that goes down with extra farming as the population increases. To simplify horribly that's why the Ming iron industry with it's chain suspension bridges and so forth collapsed.

If you're removing carbon from the air by burying trees then you'll only be able to sustain the energy intensity of civilization in the Britain of 1800, plus what we can get with renewables. What this new form of capture gives us is the ability to get rid of excess carbon without using huge amounts of arable land to do it.

I mean, we have nukes / nuclear power plants.

There are plenty of high-power ways to make energy without carbon. The question is if enough of the population can accept it.

Great perspective. I wasn't aware of the Gobi problem either

> That's why we can't "just plant trees": we'd have to be continuously planting new trees.

Yes, that's the point. Plant trees, cut them down when mature and plant new ones. Use the harvested trees to make cross laminated timber and other engineered wood products and use these to replace concrete and steel (which also release CO2 during production). As long as the timber doesn't burn or rot the carbon is stored permanently.

Trees aren't a one-time deal.

They will just release their carbon content back when they are burned or transformed in any other way that only the mineral content is left. Otherwise, paper still contains carbon. Coal (buried, not burned) contains carbon. Furniture, houses, anything you make with wood will be a way of storing carbon.

You just also need to supply water and solar light. They will grow. Simple and efficient.

This is reverse process of digging coal and sucking oil out of the earth. The problem is that we are now releasing it several orders of magnitude faster than it was put down. The Carboniferous period was a 60,000,000 years long and we will use them in much less than 600 years.

This is something that isn't often mentioned, but from what I understand this is actually kind of a one time deal with fossil fuels. I was under the assumption that the Earth is not likely to have another carboniferous period.

The implication being that we have one good shot at solving civilisation. It just gets more difficult when we start to run out of fossil fuels.

One of the reasons we don't see anything going on out there when we look up could very well be that most civilisations never properly make it off their planets.

Can anyone else comment on this that might have better information than me?

I don't think that fossil fuel is the only way to bootstrap up to a high-energy, high-complexity civilization. Hydroelectric generation also yields the sort of dependable, concentrated energy source you need for industrial development, and it was first built with 19th century technology. The necessary 19th century precursor technologies (steel, concrete, wire...) could be manufactured with wood instead of coal. Reservoir-backed hydroelectric dams can also serve, effectively, as a giant battery when you start trying to introduce more abundant but less steady energy sources like wind and solar.

The global potential of energy from hydroelectricity is only a small fraction of our current fossil-based consumption, though. And while wind and solar have potential resources far past fossil power, they can't expand as fast as fossils did historically. So the Fermi Paradox aspect might be that civilizations without fossils and without the self-control to limit reproduction are hobbled by cycles of Malthusian collapse. Or perhaps space-capable civilizations that didn't fall into the Malthusian boom-bust trap while still confined to one planet also don't go crazy with growth once they escape their gravity well, so they're out there but not leaving evidence dramatic enough to be seen by our current telescopes.

You can't really mine for high tech materials without fossil fuels. Hydroelectric won't help when what you need is to extract ore from a mountain.

Electrically driven mining equipment:

http://www.hitachiconstruction.com/about/media-press-release...

http://www.oemoffhighway.com/article/11224086/electrificatio...

If you just mean that it's impractical to build the electrical grid out to a remote mining site, that's true. In the present day remote mining sites typically use diesel fueled generators, now being supplemented with photovoltaic arrays in sunny regions. If you imagine a world with approximately-1940-level technology (so PV is not yet an option) and no fossil fuel, then you'd need to use something like biodiesel or ethanol instead of fossil-derived diesel.

> If you just mean that it's impractical to build the electrical grid out to a remote mining site

Yes, that was the general issue. We do a lot of mining in remote sites that don't have hydro power or any realistic way to get it there. You could use biofuels, but it's hard to imagine bootstrapping a technical society to the point that that becomes feasible without prior use of fossil fuels.

If you have a suitable river not too far away you actually can mine using hydromechanical power. [1] Turning it into electricity loses a lot, but transmission is of course easier

[1] http://www.lowtechmagazine.com/2013/01/mechanical-transmissi...

I think for this era, fungi and other consumers of decaying matter could not break down the cellulose walls of plant matter. Since then they did. It is interesting to imagine a species gaining sentience on a planet where there was no coal or oil to power from a wood-burning society of iron to steel and plastics.

I believe it was the lignin specifically which wouldn't decay in the Carboniferous period, leading to most of the fossil fuels around.

> I was under the assumption that the Earth is not likely to have another carboniferous period.

Well, we are busy recycling that one. All that carbon in the atmosphere will likely eventually precipitate out. On a geological timescale oil is renewable; it's simply that humans don't live that long. I suppose the cockroach civilization 60 megayears hence will be able to power their vehicles that way.

Or, you could be one of the few who believes the abiotic theory of oil production. I'm not one of them!

A sibling comment points out that back in the carboniferous period, no organisms had enzymes to break down wood. Nowadays, dead wood rots, releasing co2 back into the atmosphere.

I do think it's an important idea that fossil fuels should be seen as a stepping stone. They're not useful forever, but using them for too long is bad for all of us, and not being able to use them without a comparable alternative is an equally awful situation.

This reminds me of earthquakes that in retrospect might be caused by oil drilling, just to name one example.

Too for bad that for people in some poorer contries $478 is like many times their yearly income. But then again, their carbon footprint is most likely negligible.

Why not just let nature do it's job? If too much CO2 will kill us, then it's a self regulating system. It happened before with the Azolla event. You get fewer humans, more plants, everything else gets a chance to die off or recover, maybe a new species takes over.

Why bother with carbon sequestration?

Because people don't want to die in the ensuing conflicts over limited resources that climate change is going to bring? Because shrugging one's shoulders at the thought of widespread environmental collapse, starving populations, and the breakdown of ten thousand years of civilization is a horrible thought? Because as the droughts and famines kick in, the people that suffer the most and the most immediately for the first dozen years will be the poor and those in underdeveloped countries, while Silicon Valley programmers sip their Soylent and write comments on Hacker News like this one?

Jesus, grow some empathy.

If the world's population continues to grow exponentially it's going to happen anyway with or without expensive carbon sequestration and silly offset schemes that never work.

Rather than store carbon in solid form, which in fact plants (rainforest and such) already do anyway without the unecessary expense, why not close coal fired power stations and build nuclear? They're safer and the waste is negligible compared to coal and can be further reduced (breeder reactors, thorium cycle etc.). Burning coal also throws heavy metals (Mercury and Arsenic to name a few) and SO2/SO3 into the air. Carbon dioxide is the least of coal's problems because it can be fixed by plants or turn into bricks with additional expense.

> when trees die they release CO2

is that really true? If a tree died, i would assume the carbon is either buried, or otherwise remain solid, unless it's burnt.

The CO2 is released when (and if) the tree rots.

Dead plant matter used to become coal. Dead plant matter today decomposes:

"Based on a genetic analysis of mushroom fungi, it was proposed that large quantities of wood were buried during [the Carboniferous] period because animals and decomposing bacteria had not yet evolved enzymes that could effectively digest the resistant phenolic lignin polymers and waxy suberin polymers. They suggest that fungi that could break those substances down effectively only became dominant towards the end of the period, making subsequent coal formation much rarer."

https://en.m.wikipedia.org/wiki/Carboniferous See Rocks and Coal

That depends on how the tree decays. There is a lot of coal near the surface of the western US because prairie grass burned yearly in every dry month (winter when it was too cold to grow - they may still be as much rain/snow!). This yearly burning didn't get warm enough to burn all the carbon and so the rest got deposited as charcoal.

Moral of the story: you should start regular forest/grass fires to turn the stored carbon into charcoal. A biologist can give you a number of other reasons why this is good for the forest as well: common knowledge about forest fires is almost completely false.

Imagining a forest where dead trees never decompose is quite a mindbender. Certainly a better explanation for the presence of fossil fuels though than just a handwavey mention of geological timeframes.

Sure, but before then it's stored. And if trees are constantly creating new biomass, you've perpetually buffered an amount of carbon equal to (annual production x time variable). The first variable is limited by the thermodynamics of sunlight, so do what you can to approach that limit. Then the main target of innovation becomes, what forest management techniques can maximize that time variable?

By default about half of a tree's absorbed carbon is injected into the ground to build soil, as root mass and root exudates. Plus trees drop mulch -- mainly leaves. Soil carbon is only released when the soil is destroyed or eroded away. So... don't do that. :)

Some of it is retained in the decayed remains (eventually soil) but much is released in the decay process.

It's worth noting that the decay process takes about as long as the growth process for some trees. For example, a Douglas Fir might spend 600 years alive, and then be a Nurse Log for another 600 --- see http://www2.kuow.org/program.php?id=26100