Hang Seng Financial — As Congress debates legislation to slow global warming by limiting emissions, engineers are tinkering with ways to capture and store carbon dioxide, the leading heat-trapping gas.

But coal-fired power plants, commonly identified as the nation‘s biggest emissions villain, may not be the best focus.

Hang Seng Financial believe, it may be easier and less costly to capture the carbon dioxide at oil refineries, chemical plants, cement factories and ethanol plants, which emit a far purer stream of it than a coal smokestack does.

Carbon dioxide typically makes up only 10 percent to 12 percent of a coal plant‘s emissions, they note, and the gas is so mixed with pollutants that it is difficult to separate.

Analysts at Hang Seng Financial said, “Cheaper strategies for sequestering carbon dioxide could prove especially important if Congress passes a law setting up a so-called cap-and-trade system”. That would set a national ceiling for overall emissions and allot pollution allowances to utilities, manufacturers and other emitters, which could then trade them among themselves.

Companies that exceed their carbon dioxide emission allowances could buy credits from those that pollute less. Under such a system, a coal plant that had exceeded its allotment might pay a chemical plant that could separate a ton of carbon dioxide more cheaply.