Burying world's extra CO2 on ocean bottom
Federal energy officials have joined scientists worldwide in studying the disposal of carbon dioxide as a way of slowing down the "greenhouse effect."Skip to next paragraph
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The US Department of Energy has funded two carbon "sequestration" programs - one on land and one in the deep ocean - for $9 million. In September, it announced another $18 million in research grants.
Scientists are just now beginning to examine the disposal of carbon dioxide, one of the primary greenhouse gases linked to global warming. The idea is to get rid of carbon dioxide from factories, cars, and other sources of fossil fuel burning before the odorless gas reaches the atmosphere.
"This is to find out which carbon sequestration options are the best in the future and which ones will be verifiable," DOE program manager John Houghton says about the new research grants. "We're concerned about this in the long term."
Other countries have already begun pilot projects. A state-owned Norwegian petroleum company, for example, has been pumping 1 million tons of liquified carbon dioxide each year into depleted natural gas aquifers below the North Sea since 1996. Japan is conducting research into deep-ocean disposal, and others have suggested funneling liquified carbon dioxide into abandoned coal or salt mines, or perhaps bubbling it through CO2-scrubbing algae ponds.
Because of the vast areas available, ocean-disposal is seen as the most practical method of carbon disposal - as long as it doesn't alter the ocean chemistry and harm marine life.
The world's largest deep-ocean sequestration project is scheduled to begin next year off the coast of Hawaii. The $5 million, four-year experiment will pump liquified CO2 from a laboratory in Kona, Hawaii, through a flexible pipe, down to nearly 3,000 feet. Funded mainly by Japan with assistance from the US, Canada, and Australia, the project still faces environmental reviews from local officials.
Despite these international efforts, the US government has balked at this new field of research because of political concerns, according to federal officials. Some members of Congress believe that carbon sequestration will lead to a de facto passage of the international climate change treaty known as the Kyoto Protocols (a treaty signed by President Clinton and opposed by the Senate). And some environmentalists oppose sequestration because they believe it will allow industry to continue burning fuels that cause the problem in the first place.
Scientists themselves also question whether injecting CO2 into the ocean could be dangerous to sea creatures, or just prove to be too expensive.
DOE officials recently invited scientists to a workshop in Maryland to discuss carbon sequestration research and unveiled a draft study of existing technologies (www.fe.doe.gov/coal_power/sequestration/index_rpt.html).
The new effort by the DOE includes two research centers. One at Oak Ridge National Laboratory in Oak Ridge, Tenn., will investigate terrestrial methods of carbon sequestration: using old mines, planting more trees (which soak up CO2 for photosynthesis), or low-till agricultural methods that keep carbon locked up in the soil.
The second program is collaboration between Lawrence Berkeley Laboratory and Lawrence Livermore Laboratory to research deep-ocean injection of CO2. Researchers will also look into another option: seeding the upper ocean with iron (it acts as a fertilizer) in order to produce a massive plankton bloom, the so-called "Geritol solution."
Scientists at Moss Landing Marine Laboratory tried this method in 1995 in the Pacific Ocean 600 miles west of the Galapagos Islands. The project worked, and the plankton bloom took in an estimated 560 tons of carbon from the atmosphere. The plankton bloom also attracted tiny predators that grazed on the plants like sea-going cows munching on grass.
More recently, marine scientists from the Monterey Bay Aquarium Research Institute (MBARI) and Stanford University, used a robotic underwater submersible to inject liquid CO2 into a glass beaker nearly 12,000 feet below the ocean's surface.
CO2 dissolves in surface waters, but in deep water, liquid CO2 is denser than seawater. At low temperatures and high pressure, it forms a solid ice-like structure.
During the experiment this spring, this CO2 structure expanded until it bubbled over the beaker.
Ed Peltzer, a marine chemist at MBARI, watched the experiment on a video camera from a research vessel. Slowly, he says, the gelatinous blob of CO2 "fell to the bottom and rolled down the hill out of sight."
Several fish were drawn to the silvery structure, and poked around, but quickly swam away. Dr. Peltzer says high concentrations of CO2 are toxic to most animal life. What's more, high CO2 makes the water more acidic.
Because of a malfunction on the submersible, Peltzer and the others weren't able to see if the CO2 blob dissolved or had a permanent effect on bottom-dwelling creatures. "That's the next question we have to answer," Peltzer says.
(c) Copyright 1999. The Christian Science Publishing Society