California Gov. Arnold Schwarzenegger asked Robert Sawyer what he thought of clean coal before appointing him head of the California Air Resources Board in January 2006, to which Sawyer said, “I think it’s a great idea, but there’s no such thing.”
Sawyer, who has been a mechanical engineering professor at the University of California, Berkeley, for 41 years and is a champion of environmental research, spoke at the “Future of Coal in a Carbon-Constrained World” conference Friday hosted by the U’s Institute for Clean and Secure Energy. The event drew environmental leaders in industry and academia from around the world and featured lectures from nine renewable energy luminaries on the realities of cleansing the notoriously toxic process of coal energy production.
“We are willing our children, grandchildren, great grandchildren and great-great grandchildren our carbon dioxide emissions,” Sawyer said. “We need a lot of solutions-there’s no one thing that will get us out of this mess.”
Conventional coal-fired power plants, which yield nearly half of America’s annual electricity supply, produce one-third of our nation’s CO2 emissions. The United States sent 5,984 million metric tons of CO2 into the atmosphere in 2007, as reported by the U.S. Energy Information Administration’s preliminary figures.
Carbon capture and sequestration, two subsequent steps toward reducing the CO2 emissions of coal fired power plants, were the day’s hot topics. Capture
In the capture process, CO2 is separated from other gases in a power plant’s exit stream. Conventional power plants emit a concentration of CO2 around 15 percent. Advances in capture technologies could triple this amount, allowing more carbon dioxide to be separated and sequestered. “The cost of carbon capture and storage is almost all the cost of capture,” said Julio Friedmann, carbon management program leader at the Lawrence Livermore National Laboratory. Multiple speakers expressed this concern, but some are confident that with further research, costs will drop.
Research is underway at the U on two promising forms of carbon capture technology: integrated gasification combine cycle power generation (IGCC) and oxy-fuel combustion. IGCC technology might capture up to 40 percent of a plant’s CO2 emissions while oxy-fuel holds the potential capture as much as 60 percent.
Sequestration
Carbon sequestration is the practice of injecting and storing CO2 into porous rock layers beneath Earth’s surface.
It has been practiced commercially for more than 30 years as a means of recovering oil from depleted fields. Injecting CO2 into porous, subsurface rock layers causes a chemical reaction that modifies the remaining oil, allowing it to move more easily toward wells.
Environmentally focused, commercial use of this technology is slated to begin around 2020, scientists at the conference said. However, research and development are already underway worldwide. The U’s Energy and Geoscience Institute has conducted studies on the durability of this process in central Utah.
Safety has been a common concern in the development of sequestration.
“Security increases with time as CO2 is absorbed into rock,” Friedmann said.
George Peridas of the Natural Resources Defense Council said rock formations have stored hydrocarbons for millions of years.
However, Peridas worries about the human impact of coal extraction on residents of mining regions.
“Clean coal to these people is tantamount to cracks in their homes from blasting,” he said. “We must maximize energy efficiency and renewable opportunities first and minimize coal’s adverse effects both upstream and down.”