Geological formations could hold more than 1,000 years of carbon dioxide emissions from U.S. power plants, keeping the gas out of the atmosphere, a government report estimates.

The "Carbon Sequestration Second Atlas," released last week by the U.S. Department of Energy, reveals the potential to store 3.5 trillion metric tons of carbon dioxide in porous rock in the United States and portions of Canada. All together, the 4,600 major coal-fire power plants in the United States emit a total of 3.2 billion metric tons of carbon dioxide annually, which means the storage sites identified by the atlas could potentially hold 1,100 years of emissions from U.S. coal-based electricity generation.

Carbon capture and storage is a process whereby emissions from power plants are caught before entering the atmosphere and then pumped below ground.

This updated version of the atlas, released a year after the original, will push the technology forward, said James Slutz, assistant secretary for fossil energy, the Energy Department office in charge of the report.

"The second edition will bolster our efforts to find environmentally sound, cost-effective methods to sequester carbon dioxide," Slutz said.

Doing so is essential to halting climate change, many experts believe.

Currently the United States relies on fossil fuels for 85 percent of its energy, with 50 percent of electricity being generated by coal, according to the U.S. Energy Information Administration. In China, coal provides 80 percent of electricity. It won't be possible to suddenly step away from fossil fuels and simultaneously keep the global economy going, so capturing the emissions is the next best thing, said Sally Benson, professor of energy resources engineering at Stanford University.

"In the long, long run, we may be able to rely on zero-emissions fuels, but we'll need coal before then, so (carbon capture and storage) is an essential component to transitioning to clean fuel," Benson told United Press International.

The technology can do more than lower emissions in rich countries like the United States. As the world gears up to replace the Kyoto Protocol, the current international agreement on climate-change mitigation, one of the most controversial issues concerns the role developing countries should play.

The dirtiest technologies are almost always the cheapest, and emerging economies like China and India are spewing increasing amounts of carbon into the atmosphere as they climb the development ladder. Carbon capture and storage could help reconcile development and environmental concerns, Benson said.

"If a country has abundant coal resources, they have every motivation to use that, and having a way to make that as environmentally sound as possible will benefit everyone," she said.

But others view carbon capture and storage as a waste of money and a distraction from more promising technologies, including Emily Rochon, climate and energy campaigner for Greenpeace International, an environmental organization.

"It isn't a good idea, because it's essentially unproven and non-existent," said Rochon, author of a recent anti-carbon capture and storage report titled "False Hope." "It's going to take a lot of money and resources to ensure it will deliver, and climate-change mitigation has to happen right now."

Scientists still need to make sure the carbon won't be able to leak back into the atmosphere, and assuming the technology will be available down the road prolongs the use of fossil fuels, Rochon told UPI. Even if the technology does prove itself, she said, the atlas' storage space estimates are likely overinflated.

"They use broad guesstimates and don't have the kind of on-the-ground analysis necessary to ensure the integrity of these storage sites," Rochon said.

DOE officials replied that the atlas lists all available resources, meaning the total volume of porous and permeable sedimentary rock available and accessible for carbon dioxide storage.

"Site-specific, detailed assessments are needed to refine the estimates in the atlas," said Dawn Deel, coordinator for the atlas. Economic and regulatory constraints were not considered in assessing sites.

Deel disagreed with Rochon's assessment of the technology's readiness for deployment.

"We are ready to implement carbon capture and storage right now," said Deel, pointing to seven public-private partnerships experimenting with storing carbon dioxide right now.

"Some of the groups are injecting up to 1 million tons of CO2 into geological formations," she said.

It's true that each of the components for carbon capture and storage is ready, including gathering the carbon dioxide from power plants, the capability to transport it to storage sites via pipelines and the tools to inject the gas and monitor it once it's in the ground.

However, regulations have to be passed in order for anything to happen on a large scale, said Howard Herzog, a principal research engineer at the Massachusetts Institute of Technology.

The only way carbon capture will occur in any meaningful way is if there are policies that give businesses an incentive to do it, Herzog said.

"Until there are policies that restrict the emissions of CO2 into the atmosphere, it's always going to be cheaper to emit" instead of capture and store the gas, he said.

If businesses do receive incentives to put carbon dioxide underground, federal regulations and inspections will have to ensure the gas doesn't leak out.

"If you put it in the ground, you want to make sure it stays in there," Herzog told UPI. "You don't want to pay for something if you don't get it."

And make no mistake about it, someone will have to pay for it. Herzog and his colleagues at MIT estimate current investments in carbon capture and storage need to triple for wide-scale implementation to occur. For the federal government, that would mean increasing the annual carbon storage budget from about $300 million to $1 billion.