Carbon Dioxide Capture, Storage May Help Ease Global Warming

MONTREAL, Quebec, Canada, September 29, 2005 (ENS) - Capturing and storing the greenhouse gas carbon dioxide (CO2) produced by power plants and factories before it enters the atmosphere could play a major role in minimizing climate change, finds a new assessment report finalized here Monday by member scientists of the Intergovernmental Panel on Climate Change (IPCC).

The first summary of the global state of knowledge on carbon dioxide capture and storage, known as geological sequestration, was written by 100 experts from over 30 countries and reviewed by many experts and governments. The report assesses the most up-to-date literature available in scientific and technical journals around the world.

The report was requested by the Parties to the United Nations Framework Convention on Climate Change.

The AEP/Ohio Power Company's Amos power plant is emitting carbon dioxide into the skies over West Virginia. (Photo by Tim Smith courtesy of U.S. Army Corps of Engineers)

“Since emissions of carbon dioxide – the most important cause of climate change – continue to rise in many parts of the world, it is vital that we exploit every available option for reducing their impact on the global climate," said Secretary-General Michel Jarraud of the World Meteorological Organization.

"CO2 capture and storage can clearly play a supporting role," he said.

The report meets with the approval of Australian Environment Minister Senator Ian Campbell "Clear, objective scientific statements such as this report give us a better chance to coordinate the concerted and large-scale reductions in greenhouse gas emissions needed to avoid the worst impacts of climate change," he said.

The combustion of fossil fuels such as natural gas, oil, and coal, releases carbon dioxide into the atmosphere. The atmospheric concentration of CO2, a greenhouse gas, is increasing, raising concerns that solar heat is being trapped and Earth's surface temperatures will rise in response.

In the 200 years since the industrial revolution, the world's population has grown from about 800 million to over six billion people and the CO2 content of the atmosphere has risen from about 280 to about 360 parts per million by volume, a 30 percent increase.

“Achieving large-scale global reductions in greenhouse gases will not be an easy task," Campbell said. "The global community will need to take advantage of every opportunity to cut greenhouse gases – and carbon dioxide capture and storage is an important and potentially significant abatement option.

The United States is considering carbon sequestation as part of its technological approach to controlling climate change. A $3 billion climate change technology Strategic Plan issued by the Energy Department for public comment Wednesday sets six complementary goals, including capturing and sequestering carbon dioxide.

The IPCC report points out that many components of carbon dioxide capture and storage technology are already mature, including several applications of CO2 capture, pipelines and gas injection into geological formations.

Three carbon capture and storage projects are already in operation, in Algeria, Canada and the North Sea off the Norwegian coast.

The Sleipner complex off the coast of Norway produces natural gas high in CO2. This CO2 is removed from the natural gas stream and pumped into the Utsira Formation, a highly permeable sandstone. The operator of the Sleipner field, Statoil, geologically sequesters the CO2 because the sequestration cost is less than the Norwegian carbon emission tax. Photograph is courtesy of Øyvind Hagen, Statoil. (Photo courtesy )

The potential of capture and storage could be limited by several important non-technology constraints, the IPCC said. In particular, unless governments adopt climate change policies that put a cost on emitting CO2, there will be no incentive to use these technologies.

While the available storage capacity in geological reservoirs is “likely” to be sufficient, the IPCC said, the true amount of carbon dioxide that will need to be sequestered is stilluncertain. This is particularly so in some regions that are experiencing rapid economic growth, such as South and East Asia.

The most economically feasible storage options for CO2 are geological formations, and experience has already been gained by the oil and gas industry.

A large proportion of existing power plants and other point sources lie within 300 kilometers (200 miles) of areas that potentially contain storage reservoirs, such as oil and gas fields, unminable coal beds and deep saline water-bearing formations.

Technologies for injecting captured CO2 into the oceans may also have potential, but they are still in the research phase and have not undergone full-scale testing. They involve releasing CO2 into the ocean water column via a fixed pipeline or a moving ship, or depositing it onto the deep sea-floor at depths below 3,000 m where CO2 is denser than water.

"There are concerns regarding the impact such technologies could have on ocean life and it is known that marine organisms could be harmed," the IPCC warned

The IPCC scientists warned that the oceans might become for acidic if carbon sequestion takes place. "Although the long-term environmental implications of changing the ocean chemistry in this way are unclear," they said, "the oceans could become significantly acidified if CO2 injection occurred on a large scale."

Technologies for storing CO2 virtually permanently by converting it into inorganic mineral carbonates are also in the research phase, and certain applications have been demonstrated on a small scale.

The energy requirements for this technology, however, would need to be further improved before it could become a real option. Using captured CO2 for chemical processes in industry is technically possible but has hardly any potential for net reduction of CO2 emissions, the IPCC said.

As important as technology and cost issues are, health, safety, environmental and legal concerns would also need to be addressed to ensure public support.

Potential risks include leakage from capture, transport and injection - comparable to the risk in similar existing industrial operations - and slow leaks from storage sites.

A key legal issue would be how international law would treat CO2 injection activities in international seas.