California Portland Cement Co had planned to build more plants this year but put its expansion on hold as it awaits a decision by state lawmakers that the company says could force it to cut production. Cement manufacturers represent just one of several industries that would be required to reduce the amount of greenhouse gases they emit under a bill that would make California the first state in the nation to impose such regulations on businesses. The bill has set off a sharp debate in California over the need to balance environmental goals with the concerns of businesses that say such rules are too costly and technologically difficult.

Unlike other industries, which might be able to comply by implementing energy-efficient practices or using alternative fuels, much of the carbon dioxide emitted by cement plants is a byproduct of the chemical process. "That’s just the way cement is made," said Rick Patton, a vice president of the Glendora-based company. "If you limit the amount of carbon dioxide that can be produced, what you’re doing is limiting the amount of cement that can be produced."

The dilemma for the cement industry is among the unknowns of how, and even if, California can realistically scale back heat-trapping gases above reductions it already has achieved through previous regulations. Business leaders and researchers are divided over whether aggressive caps on industrial emissions are attainable and, if so, at what cost.

California already has been lowering its output of the greenhouse gases through a combination of energy efficient programs, alternative fuels and renewable power initiatives. But the state also is the 12th largest emitter of greenhouse gases in the world. Gov. Arnold Schwarzenegger has championed climate-change legislation, but has asked for business-friendly amendments on the current bill, which could be put to a vote in the Senate this week.

If the governor eventually signs a compromise bill, the regulations would surpass efforts in the Northeast, where seven states have announced regulations to cap and trade emissions from power plants.

The bill also would put California in step with countries that pledged to reduce their greenhouse emissions under the 1997 Kyoto Protocol, to which the US is not a party. California’s emission target for 2020, for example, would bring the state in line with today’s per capital carbon dioxide emissions in Germany, the world’s third largest economy. "We’re halfway there. We can easily do this," said the bill’s joint author, Assemblywoman Fran Pavley, D-Agoura Hills. "California can become the leader in new technologies and alternative fuels."