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Scientists review progress on capturing CO2

Approximately 250 delegates from 26 countries gathered on the MIT campus last week to discuss methods for capturing and disposing of emissions of carbon dioxide (CO2), a gas which is expected to be the largest single contributor to potential global warming.

More than a hundred papers were given at the September 9-11 conference, which was the third in a series of major biannual international meetings on the topic. One hundred sixty-two of the attendees came from foreign countries.

Topics included technologies for capturing CO2 from large stationary sources, possible uses for the captured gas and potential methods of long-term storage. Economic and life cycle assessments and comparisons with other CO2 mitigation options, notably CO2-free technologies based on nuclear and renewable fuels, were also presented.

This series of International Conferences on Carbon Dioxide Removal is a response to the Climate Technology Initiative (CTI), which was signed by 100 nations in March 1995. Among the goals of the CTI is assessing the feasibility of longer-term technologies to capture, remove or dispose of greenhouse gases, said Howard J. Herzog, chair of the conference organizing committee and principal research engineer in the Energy Laboratory. Mr. Herzog noted that CO2 capture and disposal is the only CO2-mitigation strategy that will permit continued use of fossil fuels, which now meet 85 percent of the world's energy needs.

A recurring theme at the conference was the need for policy instruments aimed at reducing CO2 emissions. Such instruments are critical if capture and disposal technologies are to become economically viable, participants agreed. Firm CO2-reduction targets and timetables are now being negotiated.

Technologies for capturing CO2 are commercially available but prohibitively expensive, speakers noted. However, several reported progress on research that could potentially lower the cost of capture technologies enough to be competitive with other CO2-mitigating approaches such as switching from fossil fuels to renewable energy or nuclear power.

Another challenge is what to do with the huge quantities of CO2 that would be captured. One possibility is using the gas in synthesizing chemicals and cultivating microalgae to serve as biomass fuel. While such uses appear promising, they could consume at most 5 percent of the CO2 now emitted by power plants.

The problem is therefore finding an acceptable method for long-term storage. Here, commercial technologies do not exist, and concerns include not only economic viability but also technical feasibility, environmental impacts and safety. Disposal in geological formations is one possible solution; depleted oil and gas wells are especially attractive because they are known to be capable of containing high-pressure gas, and companies already inject CO2 into such wells to boost their output.

Larger-volume storage may be possible in the ocean and aquifers, conferees said. Aquifer disposal is now being tested in the world's first CO2 storage project. This month, Norway will begin storing one million metric tons of CO2 per year in an aquifer under the North Sea. Norway is one of the few countries in the world that has a carbon tax, supporting the notion that policy instruments are critical to the viability of the CO2 capture and disposal strategy.

The conference was hosted by the Energy Laboratory, which has been researching CO2 capture and disposal since the late 1980s. Conference sponsors were the US Department of Energy and the Electric Power Research Institute. Co-sponsors were the Research Institute of Innovative Technology in Japan, ABB Asea Brown Boveri in Switzerland, and the IEA Greenhouse Gas R&D Programme in the United Kingdom.

Ten MIT faculty members, researchers and students spoke, including Ronald G. Prinn, Tepco Professor of Atmospheric Chemistry in earth, atmospheric and planetary sciences and director of the Center for Global Change Science; Judith T. Kildow, associate professor of ocean policy in ocean engineering; Richard S. Eckaus, Ford International Professor of Economics, and Henry D. Jacoby, William F. Pounds Professor of Management at the Sloan School.

The first conference in the series was held in March 1992 in Amsterdam; the second was in October 1994 in Kyoto, Japan. Proceedings from the third conference will be available early next year. More information can be found on the Internet at .

The fourth will be organized by ABB Asea Brown Boveri and will be held August 31-September 2, 1998, in Interlaken, Switzerland. In future, the IEA Greenhouse Gas R&D Programme will be the sanctioning organization for the conferences. Also, the scope will broaden to include the control of other greenhouse gases. Accordingly, the name will change to the International Conference on Greenhouse Gas Control Technologies.

A version of this article appeared in MIT Tech Talk on September 18, 1996.

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