Today, members of the Senate Environment and Public Works Committee will wrap up three days of hearings on the Clean Energy Jobs and American Power Act. That's the Senate version of a bill to cap emissions of global warming pollution.

Some coal-state senators, including Sen. Robert C. Byrd, D-W.Va., have sought to add language to help coal -- especially to delay emission reductions requirements and to provide more economic incentives to aid development and deployment of carbon dioxide capture and storage technology for power plants.

In a statement issued Wednesday, Byrd said he was "very pleased" with the changes made to the bill in a version released late Friday night by Committee Chairwoman Barbara Boxer, D-Calif.

Among the additions to the bill:

-- New provisions to stimulate CCS technology;

-- Advanced payments of "bonus allowances" to companies that are "early actors" installing CCS on their plants, providing they reduce emissions by at least 50 percent;

-- Requiring coal-fired power plants not to meet emissions performance standards until commercial-scale CCS technology has been deployed.

"As I have said before, we have a long way to go on this legislation," Byrd said. "Many issues have yet to be addressed. There is still a tough road ahead. But I remain dedicated to helping craft a new energy policy that will ensure that America finds cleaner, more efficient ways to use her abundant, affordable coal resources for many, many years to come."

Rockefeller spokeswoman Briana Warner was much tougher on the bill, saying earlier timelines for emissions reductions than those in a House-passed measure were "unrealistic and harmful."

The House bill required carbon dioxide emissions to be cut by 17 percent by 2020. The latest Senate version requires 20 percent emissions reductions by 2020.

"It is simply not enough time to deploy the carbon capture and storage and energy efficiency technologies we need," Warner said.

United Mine Workers union officials are also worried about the near-term pollution reductions, those requiring cuts of 20 percent by 2020. UMW officials are also opposed to part of the latest bill that retains authority for the U.S. Environmental Protection Agency to write greenhouse gas limiting regulations. The House bill stripped EPA of that Clean Air Act authority.

Eugene Trisko, a lawyer for the UMW, is schedule to testify during today's Senate commission hearing. So is Mike Carey, president of the Ohio Coal Association.

"The UMWA recognizes that climate change legislation represents the greatest threat to its membership and to the continued use of coal," Trisko will tell lawmakers, according to an advance copy of his testimony. "Achieving the proper balance among technology incentives, the timing and stringency of emission reductions, and economic safeguards will be essential for obtaining broad bipartisan support for climate legislation."

Many in the coal industry oppose any limits on greenhouse gas emissions, arguing -- despite a growing scientific consensus otherwise -- that the world is not warming or, even if it is, that human activity is not the cause.

Others in the industry, including UMW President Cecil Roberts and American Electric Power President Michael Morris, accept the scientific conclusions, but continue to argue for language to give more time for CCS to be deployed on the nation's coal-fired power plants.

CCS has never been used on anywhere the scale needed. The technology is largely untested, could be very expensive, and scientific experts believe it is unlikely to make much of a dent in carbon dioxide emissions until after 2030.