WASHINGTON -- Government and company officials and scientists on Tuesday urged more federal attention and funding for new technologies to capture and store carbon dioxide when burning coal, keeping the greenhouse gas out of the atmosphere.

Witnesses at the joint hearing of two House Natural Resources subcommittees estimated that the technology could be in widespread commercial use in 10 to 15 years, but only if well funded and researched projects begin now.

The technology would allow carbon dioxide to be captured and injected deep underground in geologic formations where it would remain trapped.

Carl Bauer, executive director of the National Energy Technology Laboratory, said that at its most rapid development the technology would be available in a decade, with broader commercial use in 15 to 20 years.

For the technology to have significant impact on reducing greenhouse gases, several hundred to several thousand carbon capture and storage facilities would need to be built around the world, he said.

The technology to dispose of large amounts of carbon dioxide is already available, Bauer said, but economic viability is a problem and the current costs "daunting." He said he met with power company officials last week who told him it would increase their overhead costs by 30 percent to capture 25 percent of carbon dioxide using current technologies.

"That's why research and development is so necessary," he said.

Bauer said the ultimate goal is to have coal power plants achieve 90 percent carbon capture with a less than 10 percent increase in the cost of electricity. The Energy Department has seven regional carbon sequestration partnerships around country working to develop the technology, he said.

A question arose at the hearing about which state and which federal agencies would best be able to promote the new technology, especially for projects on public lands. Bauer said several federal agencies need to come together to form an "aggressive team," including the EPA, Energy Department and Interior agencies with control over access to the lands.

Bauer acknowledged the government must also deal with liability issues. While a "huge outrush" of gas from the earth would "almost never" occur, he said, it's important for the public to understand the method to ensure any leaks could be dealt with.

Patrick Leahy, associate director of the U.S. Geological Survey, said the three underground areas where carbon dioxide could be injected are unmineable coal seams, saline aquifers and oil and gas wells. A national assessment should look at all three potential geologic reservoirs, he said.

Howard Herzog of the Massachusetts Institute of Technology said carbon storage technology is a critical component of mitigating climate change but is not a "silver bullet."

He noted that tens of millions of tons of carbon dioxide are injected into the ground for enhanced oil recovery. So more projects just demonstrating immediate injection are not necessary, he said. Integrated demonstrations with full monitoring are needed to lay the groundwork for large-scale deployment.

Beginning well-funded, well-constructed demonstration projects now, Herzon said, would allow the first commercial plants in 10 years.

"We need to start planting seeds immediately because of the long lead time required to bear the first fruit," he said.

Projects would need two to three years for planning, an injection period of four to five years, and another two to three years of monitoring, he said. Herzog recommended that three to five large projects be undertaken in the U.S. and eight to 10 worldwide.

Judy Fairburn of EnCana Corp. testified that the company has been injecting carbon dioxide into its Weyburn oilfield in Saskatchewan since 2000.

That makes it a commercial-scale project showing that storage of carbon dioxide is safe and effective, she said. Research shows that after 5,000 years, more than 99 percent of the gas would stay trapped underground, she added.