Washington, DC - Coal is the major fuel used to generate electricity worldwide, but burning it adds more carbon dioxide, a greenhouse gas, to the atmosphere per unit of heat than does burning other fossil fuels like oil and natural gas.

To ensure that use of coal does not continue to contribute to environmental and climate problems, scientists and engineers at the U.S. Department of Energy (DOE) are working on a portfolio of technologies that can be used to reduce carbon dioxide (CO₂) emissions from power-generation processes.

“The majority of our efforts are geared toward electric power plants,” said Thomas Shope, principal deputy assistant secretary for the DOE Office of Fossil Energy, in a May 21 USINFO interview, “because that’s the largest single opportunity for our agency to get the biggest return.”

According to The Future of Coal -- Options for a Carbon Constrained World, a 2007 study from the Massachusetts Institute of Technology, five options exist for reducing carbon dioxide emissions from burning fossil fuels:

• Improving energy-use efficiency, including transportation and electricity generation;
• Increasing use of renewable energy, such as wind, solar and biomass;
• Expanding electricity production from nuclear energy;
• Switching to less carbon-intensive fossil fuels; and
• Continuing to burn fossil fuels, especially coal, combined with CO₂ capture and storage.

“We conclude,” the study authors say, “that CO₂ capture and [storage] ... is the critical enabling technology that would reduce CO₂ emissions significantly while also allowing coal to meet the world’s pressing energy needs.”

CARBON CAPTURE AND STORAGE

Carbon capture and storage technologies allow CO₂ to be collected from fossil-fuel power stations or natural gas production facilities and stored deep underground in geological formations like saline aquifers or old oil and gas reservoirs.

As CO₂ is pumped underground, it is compressed and becomes a liquid that is trapped in small spaces between the rock grains. The longer CO₂ stays underground, the more securely it is stored.

At its National Energy Technology Laboratory (NETL) in Pennsylvania, DOE is working on research, design and development for the entire life cycle of the technology -- capture, storage and integration of both technologies in a zero-emissions power plant called FutureGen that is expected to be operational in 2012.

“The two greatest challenges facing technology development for clean power production integrated with carbon capture and storage,” NETL Director Carl Bauer told the House Subcommittee on Energy and Environment May 15, are reducing the cost of carbon capture and proving the safety and efficiency of long-term geologic CO₂ storage.

The 2012 goal of NETL’s Coal Technology Program, Bauer said, “is to show that we can develop advanced technology to capture and store at least 90 percent of the potential CO₂ emissions from coal-fired power plants with less than a 10 percent increase in the cost of electricity.”

Geological storage of CO₂ -- in use by the oil industry for more than 30 years -- is being developed and tested by several large-scale projects, including the Sleipner CO₂ Project in the Norwegian North Sea, the Weyburn CO₂ Storage and Monitoring Project in Canada, and In Salah in Algeria.

Another 25 smaller tests are ongoing through DOE’s seven Regional Carbon Sequestration Partnerships in the United States and Canada. The project is working to identify and test the most promising opportunities for CO₂ capture and storage.

All these projects and more than 15 others are part of an international climate-change initiative called the Carbon Sequestration Leadership Forum, led by DOE. Members are Australia, Brazil, Canada, China, Colombia, Denmark, the European Commission, France, Germany, India, Italy, Japan, Mexico, the Netherlands, Norway, Russia, Saudi Arabia, South Africa, South Korea, the United Kingdom and the United States.

INTEGRATING THE TECHNOLOGIES

Carbon capture and storage has not yet been applied to large-scale electricity generation, but several projects are working to achieve this, including Australia’s ZeroGen, a demonstration project for integrating coal-based gasification and carbon capture and storage to produce low-emission electricity, and FutureGen in the United States.

FutureGen is a DOE-led international initiative to build the world's first integrated sequestration and hydrogen-production research power plant. The $1B project is intended to create the world's first zero-emissions fossil fuel plant. When operational in 2012, the prototype will be one of the cleanest fossil-fuel-fired power plant.

Shope said carbon capture and storage technology will be commercially available in the 2020 time frame, and that cost is key.

“The technology needs to be developed in the right way … and we are being very diligent about it,” he said. “But we have to be cognizant of the fact that if carbon capture and storage is not [available] at a minimal increase in price, it’s not going to be applied in this country or around the globe.”

More information about the Office of Fossil Energy’s carbon sequestration program and the Carbon Sequestration Leadership Forum is available at the DOE Web site.

SOURCE: U.S. Department of Energy