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Deep thought: the effects of liquefied carbon dioxide on the ocean environment are already being studied by the University of Hawaii. Credit: MONTEREY BAY AQUARIUM RESEARCH INSTITUTE

The US Department of Energy (DoE) is investigating whether the sequestration of atmospheric carbon dioxide in oceanic or terrestrial ecosystems might be an effective way of reducing global warming.

The department has given $9 million for three years to two research centres — one each to study the ocean and land — involving scientists from various institutions. Earlier this month, the DoE solicited proposals for $18 million in carbon sequestration research, with another solicitation expected soon (see http://www.fetc.doe.gov/business/solicit ).

The budding research initiative — which will eventually require far more funds — is drawing together scientists from a variety of disciplines to study cost-effective and environmentally safe methods for the separation, capture and sequestration of the carbon dioxide emitted from fossil fuel. For instance, it might be possible to draw carbon dioxide from the emissions of a power plant, treat it and inject it deep into the ocean for storage.

The research projects are developing in a complex political climate where there is a broad consensus on the need to reduce emissions of greenhouse gases, but varying views on the most cost-effective way to do this.

Some nations, such as Japan and Norway, have aggressively pursued carbon sequestration research. But the United States has funded little research in this area, partly because of political sensitivities. Industry, which depends on fossil fuels, and its congressional advocates feared added costs, while some environmentalists felt carbon sequestration would not curb the burning of fossil fuels.

Last week, the DoE held a workshop bringing together scientists, industry, environmentalists and government officials to seek guidance for “a research road map for practical carbon sequestration technologies”, and to seek comment on its recently released draft white paper, Carbon Sequestration — State of the Science.

Scientists attending the two-day workshop in Maryland described it as an encouraging exercise that showed new cooperation among disparate parties. But they also said that a shortage of data means it will be decades before some new forms of sequestration find large-scale applications.

“There is so much we don't know,” says Howard Herzog, a chemical engineer at the Massachusetts Institute of Technology's energy laboratory, “but if we don't do the groundwork now, we won't be ready”.

With terrestrial sequestration, carbon dioxide emissions would be pumped into geological formations or old oil wells, reduced by farming techniques (such as eliminating deep ploughing), or offset by forestry procedures such as planting more trees. Small-scale applications of these methods are already being applied in some countries, mostly without controversy.

In contrast, ocean storage of carbon dioxide is seen as having great potential because of the vast areas available; but environmental issues make it a sensitive alternative. Injecting carbon dioxide may change the ocean chemistry, possibly with harmful ecological consequences.

It is these aspects of carbon storage that scientists want to study. Next month, the UK-based Environment Council will hold a workshop in New York to explore whether the injection of carbon dioxide into the ocean is “a robust environmental management strategy”. In May, the organization held a similar workshop in London.

With ocean sequestration, carbon dioxide would be liquefied and then pumped into the depths, where huge amounts of carbon already exist in forms such as carbonic acid or carbonate.

Dispersing carbon dioxide in the ocean is also being considered, but this may be even more controversial, because of concerns about more widespread ecological damage.

“We are being quite cautious,” says Jim Bishop, a marine chemist at the Lawrence Berkeley National Laboratory who is a co-director of the DoE's new Center for Research on Ocean Carbon Sequestration. “Before we pump carbon dioxide into the sea, we need to better understand how it will work.”

To that end, a team of scientists in Hawaii is preparing to conduct the most extensive experiment to date on injecting liquefied carbon dioxide into the deep ocean. The $5-million, four-year project is being funded mostly by Japan, with assistance from the United States, Norway and Canada. Australia is also expected to join.

Stephen Masutani, a mechanical engineer at the University of Hawaii who is one of the project's leaders, says the plan is to inject liquefied carbon dioxide 900 metres deep off the Kona coast in the summer of 2001.

The injection will use a small, removable pipe laid into the ocean from the Hawaii Natural Energy Laboratory. A remotely operated, mobile platform will monitor carbon dioxide dispersal at the injection site. “The idea is to obtain data for predictive models,” said Masutani. “We want to see what the changes in the sea chemistry are.”

But, despite more than two years of planning and laboratory work, Masutani says the experiment is under scrutiny from local environmental groups concerned about the impact on sea life and water chemistry.

The Hawaii team is spending considerable funds on explaining the experiment. If a full environmental impact statement is required, says Masutani, it would delay the experiment beyond the funding period set by Japan, possibly scuppering it. Decisions on the environmental assessment needed are expected in the next few months.