Urgent Evoke

A crash course in changing the world.

I started this discussion over on the discussion board - I have a calculation to put together hence bringing it back to my blog. It's demonstrated that worms fix carbon. Do they fix enough to make a serious difference to the "overflow" of the carbon bathtub? Please do check my calculations, this is important stuff and I've not had a complete night's sleep in two years (toddler daughter, bless her.)

A worm can fix 21- 63 mg/week per worm, according to this paper.

So we could say somewhere between 1000 and 3000 mg per year - call it 2g of carbon fixed per worm per year?

So in order to fix 4.1 Gt of carbon, the current overflow:

4.1*10^9 *10^3kg per year / 2*10^-3 kg per worm per year
= 2.05*10^15 worms would do the job.

Numbers can reach one to two million per acre in good farmland; in intensive cultivation somewhere around 3 000 per cubic foot. Another source has the same order of magnitude. Let's convert that to SI units - since 1 cubic metre = 35.3146667 cubic foot,

3000 worms per cubic foot = 105 944 worms per cubic metre (we'll tidy up the number of significant figures at the end as usual) and this equates to around a thousand million worms per Hectare-metre - (a metre deep).

So the volume of intensive worm cultivation we need is approximately

2.05*10^15 worms / 105 944 worms per cubic metre
= 19 349 845 200 cubic metres

1 hectare = 10 000 square metres so assuming we can cultivate the worms a metre deep, we can split cubic metres into (square metres multiplied by metres), this means the area we need for worm cultivation is about

19 349 845 200 cubic metres / (10 000 * 1 metre)
= 1 934 984.52 hectares

Let's call it around two million hectares of worm cultivation. Is that doable? We would need to find two million hectares of land that is not being used for food production (we cannot afford to further endanger the food supply by competing for land use.) Could we do worm farms on boats, moving around to unload the products at different places? I think my imagination is starting to run away with me.

It is necessary to factor in the other climate-affecting outputs of the worms - they apparently emit nitrous oxide, which is a gas with a more powerful global warming effect than carbon dioxide. We need to know how much nitrous oxide they emit, and whether it could perhaps be harvested and broken down another way, before this proposal can go further.

What else would we need to know to hack out a proposal for a field trial? How do we demonstrate the carbon fixed by the worms over a time period? Would it be possible to separate out the CaCO3 crystals for example by washing a weigh them? Sample the input and output - compare the fixed carbon in both?

I can see it could be possible to run a social enterprise fixing carbon with worms, if we can prove the carbon fixing scales properly and isn't blasted out by the nitrous oxide emissions from the worms. Since there is already a carbon offset trade for flying, perhaps this could be a replacement for that. This has a better claim to be genuinely fixing carbon than planting trees does.

Inputs required: containers, labour, food for worms (inedible organic matter), enough water to run a worm farm (we should be able to find an estimate from current worm farmers), starting stock for worm-breeding.

Outputs to distribute: finished worm compost (good planting medium), including fixed carbon (highly valuable!), worm juice (depending on cultivation style - useable for hydroponics).

I started sketching out some plans in another post.

Note: several folks have pointed out that conversion to worm-friendly farming would go a long way to fixing the carbon - but we have yet to show that it would fix the N2O part of the problem. The N2O given off would still be a big - possibly bigger - problem. Intensive cultivation with N2O trapping as I'm proposing has the potential to stop the warming effect.

It may be that organic farming also fix the N2O problem if it can be demonstrated that cultivation practices enough denitrifying bacteria. Nitrates are discouraging to denitrifiers - nitrates which are the backbone of the NPK 'green revolution' artifical fertilizers. So in conventional +NPK cultivation, fixing any of the N2O from these extra (O)10^15 worms is unlikely.

Views: 80

Tags: carbon.fixing, climate.change, worms

Comment by Nick Heyming on April 1, 2010 at 4:28am
Awesome analysis! Nitrous Oxide is 300 times worse than CO2 as a greenhouse gas, so overcoming that hurdle would be the biggest obstacle.

Instead of dedicating land specifically to worms, why not just take more farmland and stop tilling and using chemical fertilizers and pesticides but instead use practices that don't kill the native macro-fauna (worms).

There are a heck of alot more than 2000 hectares worldwide being cultivated in ways that discourage or kill worms, so by switching over a few thousand mid to large farms your goals could be achieved, even at a lower density.
Comment by Starling on April 1, 2010 at 5:51am
Thanks Nick. Yes! I have numbers for density on good organic farm - approx 1-2 M per acre. So I can calculate how many acres of new organic farm would do the same job. Obviously that is going to be a hundred times more land area.

I wonder if it also might be possible for example to harvest the nitrous oxide from intensive cultivation systems. It's a useful gas in medicine and if it might be harvested & hence replace other methods of generation? Or a breakthrough in fixing nitrous oxide as well - ther are wh*** chains of nitrifying organisms in soil?
Comment by Starling on April 1, 2010 at 6:00am
Hmm lots of organisms produce N2O - wondering if a stable ion trace experiment would show something particular that fixes it which could vat-grown. I will read up, might already have been done.
Comment by Starling on April 1, 2010 at 6:29am
Ah, and - I know N2O is around 300 times more warming than Co2 BUT - the effect of this kind of project depends on the numbers. If an order of magnitude MORE carbon is being fixed than N2O emitted we still might be able to cool the climate. It depends on the balance of CO2 fixed to N2O emitted. We need those stable ion trace experiments.
Comment by Starling on April 2, 2010 at 6:44am
Hmm, preliminary calculation suggest approx 10 :1 carbon fixed to N2O emitted. The good news is that catalytic converters already exist to convert N2O to harmless N2 + O2 - much easier than dealing with the carbon dioxide problem so this solution could still be a winner. N2O to N2 + O2 can also be done with heat. New blog post when I get a chance to finish it!
Comment by Starling on April 2, 2010 at 4:11pm
I think the partial pressure of N2O will be too low for harvesting; probably just try heat decomposition of exit gases from the closed chamber? Microbial denitrification may also be possible, as in Seneviratne and van Holm, 1998; Seneviratne and Somapala, 2003 via this summary
Comment by Michael Texeira on April 3, 2010 at 10:58am
fully in agreement with Nick here...no need to dedicate land to this. by creating the conditions for this to be put into practice on agricultural land, you might have to eliminate behaviors which are also presenting problems with this or other systems (such as water potability)

as for food, I hear worms like poop. to me, this sounds like something that could be used in its own sphere, but what interests me more is that it can easily be integrated into what other people are doing, with the Gratitude Gardens, with general permaculture projects. this is also, for some reason made me think of green roofs again. buildings with green roofs not only have a system which is reducing ambient heat reflection back into the air, but could also have immense worm density. combine that with a system them uses the septic from the house to feed the worms.

as for a better system than trees for fixing carbon...I'm not really in agreement. trees are the ultimate multi-tasking natural resource. they create shade (something me might all appreciate if global temperatures rise even 1 degree), prevent topsoil erosion, fix carbon, provide food and shelter to wildlife, and more. I do not think that there is a replacement for massive replanting efforts at this point. I do like the synergy of working with both systems. but again, for me the crux is going about working towards making (and I know this may take a while) ALL non-paved land habitable and fruitful for worms.
Comment by Starling on April 3, 2010 at 11:21am
Ok, you're obviously not someone to work on this project with me :) Thanks for your comments, I'll try to explain why I'm seeing it differently.

Did you see the difference in numbers that I posted above? Intensive cultivation leads to maybe 300 M worms /Ha; the best organic farming practices are going to be somewhere around 2-5 M worms/Ha. See the hundredfold difference? I'm not saying we don't need trees, biochar, and organic farming - we totally do. But I think we also need industrial scale carbon fixing.

Re trees for carbon fixing - it's great, but what we REALLY need are ways to get carbon locked back into the geological cycle, the place where all this excess carbon has come from, through burning fossil oil and coal.

Can you see the difference in timescale between locking carbon into wood and locking carbon into stone? Earthworms have the incredible ability to lock carbon into stone - I think this is only otherwise achievable by sending stuff to the ocean floor - and wood floats so it's harder to get it there!
Comment by Starling on April 3, 2010 at 11:22am
The other advantage of this way is that we trap the N2O that the worms give off. There's no evidence that I know of that the N2O given off by worms in organic farming systems doesn't go straight into the atmosphere. Anyone got any evidence to offer on that?
Comment by Starling on April 3, 2010 at 11:32am
Oh, and - there's no need for worm farms to be on cultivatable land. They can go on brownfield sites, desertified sites, on ships or whatever - they are not in competition with organic cultivation. This kind of project could help organic farms get going - supplying worms, wormcasts etc to help folks get their conversions going.

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