Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Some of Earth's Climate Troubles Should Face Burial at Sea

30.01.2009
Making bales with 30 percent of global crop residues – the stalks and such left after harvesting – and then sinking the bales into the deep ocean could reduce the build up of global carbon dioxide in the atmosphere by up to 15 percent a year, according to just published calculations.

That is a significant amount of carbon, the process can be accomplished with existing technology and it can be done year after year, according to Stuart Strand, a University of Washington research professor. Further the technique would sequester – or lock up – the carbon in seafloor sediments and deep ocean waters for thousands of years, he says.

All these things cannot be said for other proposed solutions for taking carbon dioxide out of the atmosphere, methods such as ocean fertilization, growing new forests or using crop residues in other ways, says Strand, who is lead author of a paper on the subject in the journal Environmental Science & Technology, published by the American Chemical Society.

Strand has devised a formula to measure the carbon-sequestration efficiency of this process and others using crop residues, something no one has done before.

Carefully tallying how much carbon would be released during the harvest, transportation and sinking of 30 percent of U.S. crop residues and comparing that to how much carbon could be sequestered, Strand says the process would be 92 percent efficient. That's more efficient than any other use of crop residue he considered, including simply leaving crop residue in the field, which is 14 percent efficient at sequestering carbon, or using crop residue to produce ethanol, which avoids the use fossil fuels, but is only 32 percent efficient.

Worldwide, farming is mankind's largest-scale activity. Thirty percent of the world's crop residue represents 600 megatons of carbon that, if sequestered in the deep ocean with 92 percent efficiency, would mean the amount of carbon dioxide in the atmosphere would be reduced from 4,000 megatons of carbon to 3,400 megatons annually, Strand says. That's about a 15 percent decrease.

The proposed process would remove only above-ground residue. Strand bases his calculations on using 30 percent of crop residue because that's what agricultural scientists say could sustainably be removed, the rest being needed to maintain carbon in the soil. Crop residue would be baled with existing equipment and transported by trucks, barges or trains to ports, just as crops are. The bales would be barged to where the ocean is 1,500 meters, or nearly a mile, deep and then the bales would be weighted with rock and sunk.

"The ocean waters below 1,500 meters do not mix significantly with the upper waters," Strand says. "In the deep ocean it is cold, oxygen is limited and there are few marine organisms that can break down crop residue. That means what is put there will stay there for thousands of years."

The article calls for research on the environmental effects of sinking crop residues in the ocean, effects that most likely will be borne by organisms living in the ocean sediments where the bales fall.

Strand says one way to minimize environmental effects would be to drop the residue onto alluvial fans found off the continental shelf wherever rivers pour into the ocean. Alluvial fans, sometimes call submarine fans when underwater, form as silt and debris from river water settles to the seafloor. Runoff from current agricultural fields means alluvial fans in the ocean are already partly made up of crop residue. Any bales dumped there would quickly be covered with silt, further ensuring the carbon would be sequestered for long periods.

Effects might also be minimized by concentrating the residue in a compact area. At the Mississippi alluvial fan in the Gulf of Mexico, spreading 30 percent of U.S. crop residue in an annual layer 4 meters, or 13 feet, deep would cover 260 square kilometers, or 100 square miles. That's about 0.02 percent of the area of the Gulf of Mexico, Strand says.

"Whatever the environmental impacts of sinking crop residue in the oceans turn out to be, they will need to be viewed in light of the damage to oceans because of acidification and global warming if we don't remove carbon dioxide from the atmosphere," Strand says.

Co-author of the paper is Gregory Benford, a professor of physics at the University of California, Irvine.

Strand, a faculty member with the UW's College of Forest Resources, is an environmental engineer known for his work on using plants to remediate contaminated groundwater, soil and sediment. He said he's been interested in ways to remove carbon dioxide from the atmosphere for nearly a decade and first read about sequestering crop residue in the deep ocean in Climatic Science in 2001. Benford was a co-author on that paper.

Strand says he thinks any method for removing excess carbon dioxide must do seven things: move hundreds of megatons of carbon, sequester that carbon for thousands of years, be repeatable for centuries, be something that can be implemented immediately using methods already at hand, not cause unacceptable environmental damage and be economical. He says sequestering crop residue in the deep ocean fits the criteria better than any other proposed solution.

"To help save the upper ocean and continental ecosystems from severe disruption by climate change, we must not only stop our dependence on fossil fuels, but also go carbon negative," Strand says. "Fossil fuels that are removed from sediments and burned are producing the increased atmospheric carbon that is driving climate warming. Sequestering crop residue biomass in the deep ocean is essentially recycling atmospheric carbon back into deep sediments."

For more information:
Strand, 206-543-5350, 206-605-2221, sstrand@u.washington.edu
"Ocean Sequestration of Crop Residue Carbon: Recycling Fossil Fuel Carbon Back to Deep Sediments" is available online to subscribers of Environmental Science & Technology (see Jan. 12) and is expected to appear in the print edition next month.

Sandra Hines | Newswise Science News
Further information:
http://www.washington.edu

More articles from Ecology, The Environment and Conservation:

nachricht Despite government claims, orangutan populations have not increased. Call for better monitoring
06.11.2018 | Deutsches Zentrum für integrative Biodiversitätsforschung (iDiv) Halle-Jena-Leipzig

nachricht Increasing frequency of ocean storms could alter kelp forest ecosystems
30.10.2018 | University of Virginia

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: A Leap Into Quantum Technology

Faster and secure data communication: This is the goal of a new joint project involving physicists from the University of Würzburg. The German Federal Ministry of Education and Research funds the project with 14.8 million euro.

In our digital world data security and secure communication are becoming more and more important. Quantum communication is a promising approach to achieve...

Im Focus: Research icebreaker Polarstern begins the Antarctic season

What does it look like below the ice shelf of the calved massive iceberg A68?

On Saturday, 10 November 2018, the research icebreaker Polarstern will leave its homeport of Bremerhaven, bound for Cape Town, South Africa.

Im Focus: Penn engineers develop ultrathin, ultralight 'nanocardboard'

When choosing materials to make something, trade-offs need to be made between a host of properties, such as thickness, stiffness and weight. Depending on the application in question, finding just the right balance is the difference between success and failure

Now, a team of Penn Engineers has demonstrated a new material they call "nanocardboard," an ultrathin equivalent of corrugated paper cardboard. A square...

Im Focus: Coping with errors in the quantum age

Physicists at ETH Zurich demonstrate how errors that occur during the manipulation of quantum system can be monitored and corrected on the fly

The field of quantum computation has seen tremendous progress in recent years. Bit by bit, quantum devices start to challenge conventional computers, at least...

Im Focus: Nanorobots propel through the eye

Scientists developed specially coated nanometer-sized vehicles that can be actively moved through dense tissue like the vitreous of the eye. So far, the transport of nano-vehicles has only been demonstrated in model systems or biological fluids, but not in real tissue. The work was published in the journal Science Advances and constitutes one step further towards nanorobots becoming minimally-invasive tools for precisely delivering medicine to where it is needed.

Researchers of the “Micro, Nano and Molecular Systems” Lab at the Max Planck Institute for Intelligent Systems in Stuttgart, together with an international...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

“3rd Conference on Laser Polishing – LaP 2018” Attracts International Experts and Users

09.11.2018 | Event News

On the brain’s ability to find the right direction

06.11.2018 | Event News

European Space Talks: Weltraumschrott – eine Gefahr für die Gesellschaft?

23.10.2018 | Event News

 
Latest News

In focus: Peptides, the “little brothers and sisters” of proteins

12.11.2018 | Life Sciences

Materials scientist creates fabric alternative to batteries for wearable devices

12.11.2018 | Materials Sciences

A two-atom quantum duet

12.11.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>