TOPICS > Science

Scientists Seek to Minimize CO2 Impact

August 6, 2001 at 12:00 AM EDT
REALAUDIO SEE PODCASTS

TRANSCRIPT

SPENCER MICHELS: Off the California coast, researchers are doing ocean-floor experiments that may affect the nature of the debate over global warming. Up to now, that debate — at numerous international conferences — has focused on proposals to reduce emissions into the atmosphere of carbon dioxide, which is considered a major contributor to global warming.

ROBERT WATSON, Chief Scientist, World Bank: We humans are affecting the Earth’s climate system and our projected changes in climate are larger than we had said five years ago.

SPENCER MICHELS: As the argument continues –and CO2 production increases — scientists are looking intensely for ways to permanently store the odorless, colorless gas. One of the possible solutions is to liquefy the gas and then place it on the ocean floor.

Ever since the Industrial Revolution, man has been producing more and more carbon dioxide, by burning fuels containing carbon. Today, 25 billion tons a year are produced. While much of the CO2 is absorbed on Earth in plants and the ocean surface, a huge amount goes into the atmosphere, where it and other gases create a kind of lid around the globe –the so-called greenhouse effect. Heat that would normally escape into space is thus reflected back to Earth, raising global temperatures.

Although President Bush first sounded skeptical that removing CO2 and storing, or sequestering, it was practical, after environmentalists loudly objected, he softened his position.

PRESIDENT GEORGE W. BUSH: We all believe technology offers great promise to significantly reduce emissions, especially carbon capture, storage and sequestration technologies.

SPENCER MICHELS: Currently the federal government is spending $40 million a year on CO2 disposal projects, and scientific research institutions like MBARI, the Monterey Bay Aquarium Research Institute, and private industry are investing even more. Peter Brewer and James Barry — MBARI scientists –have just returned from a trip in which they used a remotely operated vehicle to put liquid CO2 on the ocean bottom.

PETER BREWER: The two of us went out and set up a science lab on the sea floor, and we deployed some little corrals that would hold the carbon dioxide, and then we collected animals and placed them close by, so we observed both the chemical changes in the carbon dioxide, and the biological responses.

SPENCER MICHELS: The CO2 used in the unfinished MBARI experiments remains in liquid form because of the pressure down deep. Brewer and Barry use a remote camera in the robot vehicle to observe the CO2.

PETER BREWER: It will react with the seawater to form an ice-like solid compound, and we now have images of that on the sea floor, and it’s very beautiful.

SPENCER MICHELS: The ice-like compound — carbon dioxide hydrate – may keep the liquid CO2 from mixing with the seawater, according to U.S. Geological Survey Researcher Laura Stern. But at room temperature, in the lab, the hydrate crust deteriorates.

SPENCER MICHELS: Basically we’re seeing this carbon dioxide hydrate decompose -

LAURA STERN: We’re seeing it decompose, as it releases the gas, and the hydrate structure decomposes to ice and then the ice will melt to water as the gas is released.

SPENCER MICHELS: So this is just what you don’t want to happen on the floor of the ocean if you’re using it for sequestration.

LAURA STERN: That’s correct.

SPENCER MICHELS: So how do you prevent that?

LAURA STERN: At this point the properties of CO2 hydrate really aren’t known very well.

SPENCER MICHELS: Another unknown: Will large quantities of liquid carbon dioxide stay on the ocean bottom intact — and for how long? Researcher Peter Brewer.

PETER BREWER: You can put it down there, but it will slowly dissolve and become mixed in the ocean water. And that’s okay. But very little would come back to the atmosphere because of the buffer capacity of the ocean, its chemical ability to hold the CO2 in there, rather than let it go back to the atmosphere.

SPENCER MICHELS: Large amounts of CO2 could affect marine life. Barry says respiratory stress in sea animals might result.

JIM BARRY: The second consequence is metabolic stress associated with CO2, and that’s less understood, but in some animals it causes them to enter a state or torpor or hibernation, so we may not kill these animals, but we may suspend them into a sort of state of hibernation in some cases.

SPENCER MICHELS: That doesn’t sound very good.

JIM BARRY: Well, that’s the problem: How large a problem will this be? And it depends both upon the extent of the animals to tolerate changes in CO2 chemistry and the aerial extent of the CO2 plumes associated with large-scale injection.

SPENCER MICHELS: Those uncertainties have prompted environmentalists — including David Hawkins at the Natural Resources Defense Council — to oppose ocean sequestration.

DAVID HAWKINS: We don’t know what will happen to the organisms living in the oceans, we don’t even have a good idea of what all the organisms are that live in the oceans. Second, we don’t what would happen to the CO2 in the oceans; we don’t know how long it would stay there, whether it would bubble back to the surface or get transported in huge ocean currents and come back into the atmosphere.

SPENCER MICHELS: Video taping his own meetings, Hawaiian fisherman Isaac Harp has formed the Coalition Against CO2 Dumping — to prevent a large scale ocean floor experiment in waters off Hawaii.

ISAAC HARP: This area where they propose to inject CO2, they want to inject this into probably the most productive pelagic fishing ground in Hawaii, and that is totally ridiculous, not even taking that into consideration

SPENCER MICHELS: The Hawaiian experiment has been delayed. Those doing research off California admit it would be better not to dump CO2 in the ocean, as a kind of waste management. But –they say — disposal may be less detrimental than releasing it into the atmosphere.

JIM BARRY: All the effects that we expect of global climate change, changing agricultural regions, forests, et cetera.

SPENCER MICHELS: So you’re talking about a kind of a trade-off, right?

JIM BARRY: Exactly. It could be a big tradeoff, and we have some decisions to make as a society of what we value the most, and we may have to sacrifice some for the benefit of others.

SPENCER MICHELS: Another plan to get rid of CO2 being touted by some is to increase plant life in the ocean by adding a solution of iron to the water. Plants absorb carbon dioxide. Ken Coale is director of the Moss Landing Marine Labs.

KEN COALE: When iron gets blown into the ocean, it promotes plant growth. As the plants grow, they absorb carbon dioxide from their surroundings, and then as the plants die, they sink out, virtually removing carbon dioxide from the atmosphere.

SPENCER MICHELS: Coale says vast areas in the oceans get little iron, and therefore support almost no plant life. Experiments he has done — putting iron sulfate in the water and watching plant life bloom – show that iron could make a big difference.

KEN COALE: The cat is out of the bag. We know oceans respond to iron. And there’s so little iron in the ocean right now that adding a little bit more is not going to hurt the chemistry. It will dramatically affect the plankton populations; we know that; we know that it will dramatically affect productivity; we know that it will draw down CO2.

SPENCER MICHELS: Yet another technology already in use is injecting CO2 into oil wells, which forces more oil from the wells. Pan Canadian Resources is importing CO2 from North Dakota via a pipeline, and leaving the liquid carbon dioxide in the ground, resulting in a net reduction in greenhouse gasses. The technique is 30 years old, but, according to Franklin Orr, Dean of Earth Sciences at Stanford, the emphasis on sequestration is new.

FRANKLIN ORR: If you have a piece of rock in an oil reservoir, it contains small pore spaces, that’s where the oil is, and as the oil comes out it needs to be replaced by some other fluid and that fluid might as well be CO2. If we use the CO2, it means that we don’t have to use water to replace the oil and we can prevent the CO2 from getting to the atmosphere.

SPENCER MICHELS: Orr says that oil deposits — sealed deep underground — don’t escape unless disturbed, and neither would carbon dioxide.

FRANKLIN ORR: We know that oil reservoirs have contained oil for million of years, so there’s a seal, there’s a set of geological structures that will contain the CO2 as long as we haven’t done something to damage the seal.

SPENCER MICHELS: CO2 can also be stored in other geological formations in parts of the country not near oil fields. Even environmentalists aren’t completely opposed to using underground storage.

DAVID HAWKINS: It does make sense in our view to explore storing carbon underground in stable geologic formations. We think there’s technical promise there and we think that as part of a portfolio of responses that this could be something that could work out.

SPENCER MICHELS: An unsolved problem for many of these techniques is capturing carbon dioxide at its source, before it is released into the air, so it can be liquefied and disposed of.

At the Moss Landing power plant a huge scrubber chemically removes some polluting gasses including nitrogen oxide from the exhaust. But there is no equivalent device available to collect CO2 on a large scale. Duke Energy is retiring and dismantling an old power unit, and erecting a new one, which will burn gas more efficiently, emitting less carbon dioxide.

But scientists say efficient power plants alone will not solve the problem of too much CO2. Many contend that all approaches to carbon dioxide reduction need to be evaluated now because the problem of greenhouse gas is becoming critical.

PETER BREWER: By about the year 2025, we’re going to have to be putting away very large amounts of carbon dioxide somewhere. If that’s going to happen in 2025, things should start being built about 2015. And we should have the research done by about 2010, and the clock is ticking right now.

SPENCER MICHELS: Still, environmentalists are uneasy with the new emphasis on CO2 disposal. They continue to push for more efficient cars and power plants, and lower energy use.