Researchers: Cut Carbon Dioxide by Dumping Crop Waste into the Ocean
It’s a decidedly low-tech way to deal with a 21st century problem, but a newly published paper argues that the world can cut carbon dioxide emissions up to 15 percent a year by taking the crop waste leftover after the harvest and dumping it into the deep ocean.
Stuart Strand of the University of Washington and coauthor Gregory Benford of the University of California at Irvine argue in the journal Environmental Science & Technology that such a reduction is possible by dumping 30 percent of world crop residues at least 1,500 meters deep in the oceans. The method would lock up the carbon in the crop waste deep underwater for thousands of years, the authors said.
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The deep ocean waters do not mix with waters and currents closer to the surface and would lock the crop waste in place. And if the wastes are dumped near “alluvial fans”– places off the edge of the continental shelf where rivers meet the ocean–the waste would be buried by silt from those rivers (see map). The cold waters would prevent decay, the authors say.
If 30 percent of the world’s crop waste is sunk annually, it could remove about 600 megatons of carbon–a roughly 15 percent reduction of CO2 in the atmosphere. Strand worked out a formula to rate the efficiency of other methods of disposing of carbon, and said his process topped the rating at 92 percent efficiency.
Even turning the crop waste into ethanol is only 32 percent efficient, the authors said.
The authors suggest baling the crop leftovers and trucking them to barges that would move the stuff to deep waters, where it could be sunk and weighted down with rocks.
While the technology for offshore burial already exists, it’s not clear how much it would cost. One recent estimate from the Earth Policy Institute estimated that carbon sequestration would cost $210 per ton through tree planting and agricultural management practices.
This clearly remains in the idea stage of development. No matter how secure and stationary the waste might be, the idea of dumping anything in the oceans is sure to be a hard sell. The authors call for more research on just how such a scheme would impact the creatures living in those deep sea zones.
Map Credit: University of Washington
An interesting idea, seemingly along the same lines as biochar sequestration that James Lovelock thinks is humanity’s only hope.
Surely this method will ensure nutrient depletion from agricultural lands leading to the requirement for replacement nutrients (fertiliser) to be added? After all, crop waste doesn’t just contain carbon but nitrogen and minerals too.
As for dumping millions of tonnes of waste over the edge of a boat, doesn’t seem like good environmental stewardship to me when you take into account how little we already know about these deep water ecosystems (except how fragile they are and how long they can take to recover).
Dump 30% of crop waste into the ocean? This is a ridiculous, juvenile and careless idea. Just because a paper is published does not give it merit. “Strand worked out a formula to rate…” Is this a joke?
The authors of this “newly published paper” should be fired and banned from the scientific community for such a dangerous and proposterous idea.
Matt and David, I agree with you both, at bare minimum this needs idea needs a lot more thought. I’m hearing Jeff Goldblum’s voice from Jurassic Park saying “life finds a way.”
This idea seems incredibly difficult to accomplish for a number of reasons. Transportation/collection costs aside, how could one assure that low-density crop wastes would reach deep ocean levels without getting swept away by surface currents? Sequestration via pyrolysis and biochar has the potential to remove significantly more CO2 from the atmosphere at what is likely a much lower cost. In addition, if biochar is returned to depleted soils the nutrient loss can be reduced or even eliminated.
Dumping crops into the ocean is a dumb idea. Crop residue is needed to keep the land fertile, as it retains water and turns back into good soil for future crops. What’s dumped into the ocean will only harm the ocean in the long run. Besides, erosion is already a huge problem and taking crops to dump them into the ocean only speeds up the process by manually moving what once was earth/soil to the ocean. Don’t do it!
So the deep ocean is now the new “away”. Fix the problem at the source instead of passing it off for someone else to clean up and further ruining the planet. We have enough of these “breakthrough” ideas already. Maybe if we didn’t use food for fuel we wouldn’t have this problem in the first place. I’m glad to see that everyone’s response so far is against this idiotic idea.
This is the equivalent of strip mining our agricultural soil.
There is no such thing as crop waste. Alan Chadwick (http://www.ecotopia.org/ehof/chadwick/index.html) called compost “The Gold of the Garden”. He advocated using about 1/3 of agricultural for growing crops for compost.
Using this method the fertility of the land would increase each year. The result would be increased agricultural productivity which would remove more CO2 from the atmosphere. The increased agricultural productivity would probably more than enough to make up for the loss of production from using 1/3 of the land for soil improving crops.
Regardless spending money and using energy to transport it to the ocean for dumping is nuts.
Mitch
Doesn’t this seem like it’s pushing the problem on to generations after us? Granted, it would be a lot of generations after us, but eventually that CO2 would get back up to the atmosphere, or potentially acidify the oceans as well.
Silly idea.
Transportation and soil health issues aside, it doesn’t make sense to dig up filthy coal and burn it while trying to bury clean burning biomass. Before we start thinking about putting carbon into the earth we should stop digging it out.
Repeat after me, “Coal is the enemy.”
Uh… you guys do know Gregory Benford is a Science Fiction writer, right?
See http://en.wikipedia.org/wiki/Gregory_Benford for details.