We have heard for dozens of years about how plastics remain in landfills for thousands of years. Now that atmospheric carbon accumulation is recognized as bad, maybe the landfill for thousands of years is a good place for plastic to stay. Is there some way we could capitalize on this property to sequester more carbon?

Currently most plastic is made from petrochemicals: fossil carbon. If it goes back into a landfill, it is neither a net gain nor loss for the atmosphere.

I propose that large scale CO2 emitters (probably coal and gas power plants) recapture a portion of CO2 by reducing it to ethylene. This would be charged to the power producers. The fed would subsidize this by guaranteeing a market for the ethylene, allowing the power producers to recoup some of their costs.

Ethylene is a valuable feedstock for making plastics, and the flood of cheap ethylene would allow plastic makers to stop using petrochemicals. The cheapness of the plastic thus produced would lead to even more plastic things than is now the case. All of this plastic would ultimately wind up in landfills (or the ocean), sequestering the carbon contained in it.
-- bungston, Feb 12 2007

Reduction of CO2 to ethylene http://adsabs.harva...1998uisr.work...49R
These folks are trying to figure out how to make things on Mars. Pretty cool in and of itself! [bungston, Feb 12 2007]

The synthetic tree http://news.bbc.co....ci/tech/2784227.stm
one tree, 15000 cars worth of pollution [jonthegeologist, Feb 13 2007]

Bury trees - reduce greenhouse gasses? Bury_20trees_20-_20...enhouse_20gasses_3f
More practical, I think. [ldischler, Feb 14 2007]

Looks like this process requires lots of hydrogen - it'd be perfect if there was plenty of free hydrogen just hanging around (although if there was plenty of free hydrogen hanging around we probably wouldn't be needing to seqester carbon dioxide in the first place).

I think it would be easier to make hydrocarbons instead using carbon dioxide + sunlight (e.g. trees).
-- xaviergisz, Feb 12 2007


I'm not an expert, but am fairly sure that the energy required to reduce CO2 to ethylene would, at best, equal the energy generated by its creation. You've proposed a very roundabout way of converting oil to ethylene.

Otherwise, fantastic, you've created a perpetual motion machine. just burn the ethylene and reduce the CO2 back again, in a closed loop.
-- TheLightsAreOnBut, Feb 13 2007


[bungston] is on to something here. Our environmental problems are borne of our incessant conversion of geocarbons (fossils fuels) into biocarbons (atmospheric CO2, CH4 and others, taken up by plants)

Planting fooking trees is absolutely pointless and just delays the inevitable. Sure, the trees take up CO2 from the atmosphere, but the fixed carbon is short term because, once the tree dies, the carbon is released back into the atmosphere. Sorry [xaviergisz], your photosynthesis idea will never save the planet, unless you're planning on burying the trees in such a way that they become geocarbon as occured in the Carboniferous.

Biodegradable plastics look, on the face of it, very environmentally friendly. But what are they actually doing? It's a conversion of geocarbon into biocarbon and actually accelerates the issues we have.

[Bungston]'s non-biodegradable plastics idea sees geocarbons converted to plastics that then remain fixed - they cannot then degrade into atmospheric CO2 and contribute to warming. Clever. What you do with this fixed carbon is the next game. Burying will work, but I agree with [humanzee] that there might be some better, smarter, alternatives.

Programmes then that take CO2 outputs from manufacturing and convert to nondegradeable plastics could be the future.

[I won't name names, but I know of a Professor of Biogeochemistry who is seriously looking into the energy sums of precisely this]
-- jonthegeologist, Feb 13 2007


Assuming that [jtg]'s second para above is accurate - a safe assumption, I would have thought - the optimum sequestration strategy would be to plant lots of fast-growing trees then chop them down and bury them in big holes.
-- angel, Feb 13 2007


I'm still sceptical about [jtg]'s 5th para, though. Unnamed Professors should know better. Converting CO2 into plastic could only be useful on a planet that has an excess of renewable energy. Same problem with [angel]'s otherwise great suggestion, it would be better to burn the trees rather than bury them and burn oil. Burying trees also buries vital plant nutrients etc, which is another problem.
-- TheLightsAreOnBut, Feb 13 2007


you're right to be sceptical about the 5th para, which is why I have written that the sums are being looked at.

It could well be that *making* plastics from atm CO2 to fix carbon, deliberately, is inappropriate, but that deliberately making nondegradable plastics from geocarbon is the best step forward.
-- jonthegeologist, Feb 13 2007


OK, but there's still a problem: unless CO2->C2H4 is a low energy process (Very unlikely), you're burning oil to generate the energy to do this. Or, alternatively, you could synthesise your plastic from the same oil. This is not a viable solution until we are generating sufficient energy from non carbon sources
-- TheLightsAreOnBut, Feb 13 2007


[Lights]: I was suggesting a method of sequestering existing atmospheric carbon, not attempting to ameliorate the combustion of more fossil fuel; not "growing and burying trees while burning oil" but "growing and burying trees while using some other, non-carbon, fuel". You seem to be assuming that oil must be burned in order to generate power.
-- angel, Feb 13 2007


[Bungston] - this is brilliant! I take back all the things I said, apart from the ones involving amphibians. [+]
-- MaxwellBuchanan, Feb 13 2007


/unless CO2->C2H4 is a low energy process / yeh, I suspect a fair amount of the energy used burning the oil would be consumed in unburning it.
-- bungston, Feb 14 2007


This idea just resonates with bad business!
-- quantum_flux, Feb 14 2007


[angel]: I agree that /using some other, non-carbon, fuel/ is the holy grail, unless the non-carbon fuel is a dirty, messy, screw-the-planet-up-even-more -than-carbon-fuels process. We'll probably find that there's always a compromise, compromise being defined as "when two or more parties agree on something that no-one wanted in the first place."

HOWEVER, given that: TRY IT! Go on, stop using energy generated by oil, right now. Can't do it? That'll be because x% of the world's electricity generators are carbon-fuel-powered. These have a service life of about 50 years, so we're looking at about 50 years to eliminate them if we can persuade everyone to stop building new ones today.
-- TheLightsAreOnBut, Feb 14 2007


I totally agree. The major problem is that the obvious, clean, efficient, safe, cheap alternatives (pebble-bed reactors) are dismissed for entirely political reasons, while ever-higher taxation of carbon fuel both generates enormous revenue and appeases the eco-lobby. What's needed is to get governments out of the decision-making process altogether, and let power-generating companies decide how they're going to do it. They'll almost certainly go for the best option.
-- angel, Feb 14 2007


Google search for "pebble-bed reactors" informs me that the website uk.Best-Price.com offers:

Pebble Bed Reactors Cheaper, better, now! Incredibly low prices

I think I'll just go buy one for my garden. I'll bury the waste with all that plastic.
-- TheLightsAreOnBut, Feb 14 2007


//available at most petrol station forecourts//

But not in the US apparently, according to Eddie Izzard.
-- theleopard, Feb 14 2007


Plastics don't grow on trees, you know.
-- SledDog, Feb 14 2007


Will this let us have our -O2 back?
-- BunsenHoneydew, Feb 15 2007


Umm... agree with LightsAreOn and many others... Turning CO2 into anything other than CO2 requires energy. Ethylene more than most actually. Think about it: if you could turn CO2 to ethylene (C2H4) using less energy than you gained by burning C2H4 and turning it into CO2, you would have a perpetual motion machine. It simply doesn't make sense.

Letting plants convert CO2 into chemically reduced forms of carbon by photosynthesis is far more efficient than any man-made process... so stop burning and just wait. Things will take care of themselves reasonably quickly if we just go 100% renewable.
-- Agamemnon, Feb 15 2007


Plants are the way to go.

Imagine a tree or a grass that produces small grains of some non biodegradable organic compound care of generic engineering. As the leaves fall and decompose, the granules of the non biodegradable stuff mix into the soil and the carbon stays there,
-- vmaldia, May 23 2009


//grass that produces small grains of some non biodegradable organic compound// I like that idealette. The plastic granules would presumably just mix with the soil and cause no real harm. They might even improve drainage. In centuries to come they could even be harvested as a petrochemical feedstock.

The problem is that the plants would struggle. They're devoting a proportion of their resources to synthesizing the plastic granules, with no return. This means they'd be outcompeted by wild strains, or would revert, making it a high-maintainence project.
-- MaxwellBuchanan, May 23 2009


Nature would have a go at the soiled plastic granules in the form of evolving micro-organisms, which may or may not be beneficial to the human species.
-- wjt, May 23 2009


Why does it have to be plastic? How about we implement a positive-net-energy process where fossil fuels are converted into graphite/buckyballs + H20! Then we can bury the pure carbon like the plastics.
-- ViolentQuaker, May 24 2009


//Then we can bury the pure carbon like the plastics.//

Then why not just bury the coal? In fact, why bother to dig it up?
-- ldischler, May 24 2009


Hey ViolentQuaker, Greets from the west coast of the USA. Don't go away. Represent for Friends! Together we can hold them in the light until they burn! Never give up the good fight, there are more of us than you might think.
-- WcW, May 25 2009



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