U.S. scientists say they've found an improved way to remove carbon dioxide, the major global warming greenhouse gas, from smokestacks and other sources.

Researchers at the University of Southern California, writing in the Journal of the American Chemical Society, say they've achieved some of the highest carbon dioxide removal capacity ever reported for real-world conditions.

Existing methods for removing carbon dioxide from the atmosphere, as well as from smokestacks and other sources, are energy intensive, don't work well and have other drawbacks, they said.

The researchers turned to solid materials based on polyethylenimine, a readily available and inexpensive polymeric material, and found the inexpensive materials achieved some of the highest carbon dioxide removal rates ever reported for humid air, under conditions that defeated other related materials.

After capturing carbon dioxide, the researchers said, the materials give it up easily so the CO2 can be used in making other substances or permanently isolated from the environment.

The capture material can be recycled and reused many times over without losing efficiency, they said.

The researchers suggest the materials may be useful on submarines, in smokestacks or out in the open atmosphere, where they could clean up carbon dioxide pollution that comes from small point sources like cars or home heaters.

Such sources represent about half of the total CO2 emissions related to human activity, they said.