Overshadowed by the still-unresolved budget battle in Harrisburg, another legislative drama is playing out in relative obscurity. It involves arguably the most important piece of energy/environmental legislation pending in Pennsylvania.

"The bill is absolutely crucial to Pennsylvania's economy, and public health, and environment for the next 15 years," said John Hanger, secretary of the Department of Environmental Protection. "The stakes are big."

So are the competing interests.

House Bill 80 has pitted roofers against electricians, coal companies against nuclear-plant operators. At times, even the environmental community has been divided over some of its provisions.

The measure would bolster clean-energy standards so they are at least on par with those in a number of other states with more ambitious requirements, including New Jersey. It also would enhance Pennsylvania's commitment to alternative energy, an area in which the state has made substantial progress under the Rendell administration but wants to do more - and soon, to capitalize on available stimulus money.

"What's at risk is tens of thousands of jobs and billions of dollars of investment," Hanger said Friday.

Specifically, the bill would amend the state's Alternative Energy Portfolio Standards Act, which the legislature adopted in November 2004. That law required that utility companies, by 2021, derive at least 8 percent of the energy they distribute from certain defined renewable and alternative-energy sources. House Bill 80 would increase that to 18 percent by 2024, though a planned amendment to increase the bill's chances of passage would modify that to 15 percent.

"That's unfortunate that we need to cut that," Hanger said. "But the amendment is supported by the governor and myself. We're practical people."

Evidence of just how much the bill is not sitting well with a variety of groups - and legislators - is in the number of amendments it has attracted so far: 30.

"It's important to defeat most of those amendments to maintain the integrity of the bill," said Rep. Greg Vitale (D., Delaware), the measure's prime sponsor and a member of the House Environmental Resources and Energy Committee. The panel passed the bill on to the full House a month ago.

With "between 80 and 90" of the required 102 votes needed to get the bill through the House and over to the Senate, Vitale said he was "now engaged in a lobbying effort to bring more and more members on board." In the state's coal regions, he said, opposition stems from concern that "the more renewables are used, the less coal will be burned, and that will cost jobs."

Sprinkle in such concepts as "carbon capture sequestration," activists' concerns about environmental degradation, and fears about the loss of market share by certain industry groups, such as coal and nuclear, and you have the controversial stew that is House Bill 80.

Interest groups have sent letters and e-mails to legislators' offices reflecting a mix of opinions.

Solar installers, for instance, are fighting an amendment sponsored by Rep. Bill Keller (D., Phila.). Supported by the International Brotherhood of Electrical Workers (IBEW), the amendment would require that all solar-photovoltaic systems and components be installed by licensed electrical contractors.

"This amendment pretty much cuts out the established industry of installers," said Kira Costanza at Sunpower Builders, of Collegeville, her father's 33-year-old solar-installation business.

It is an industry largely in its formative stage, given that Pennsylvania only started offering solar rebates to homeowners and small businesses in the spring. Roofers and other contractors consider it a natural extension of their skills.

The IBEW has cited safety concerns in pushing for the Keller amendment, Costanza said. There is room for compromise, she added, and solar-trade groups are working with the IBEW to reach one.

Keller and representatives of IBEW's Local 98 in Philadelphia did not return several calls for comment over the last two weeks. According to campaign-expense reports, the IBEW and Local 98 have contributed a total of $186,950 to Keller's political campaigns since 2000. Keller has been a state representative since 1993 and was last reelected in 2006.

Maureen Mulligan, a lobbyist for the solar industry, said Pennsylvania already has a system in place to ensure that solar installations are done safely. She noted that all projects must be installed by contractors approved by the Department of Environmental Protection to qualify for state rebates. Those jobs also must pass muster with code officials certified by the state Department of Labor and Industry. The solar industry is in talks with the department, Mulligan said, to get additional solar training for inspectors.

What the solar industry particularly likes about the bill is a provision to increase solar's share of the state's alternative-energy portfolio standards. Currently, those standards require that solar be the source of at least 0.5 percent of the alternative energy that utilities must tap. House Bill 80 would increase that minimum share to 3 percent by 2024.

Among environmentalists, the concern is over the bill's provisions for carbon capture and sequestration. The process involves capturing carbon dioxide emissions from large sources such as power plants, compressing it, and storing it away from the atmosphere.

Nathan Willcox, an energy and clean-air advocate at nonprofit PennEnvironment, said the group would not support the bill unless some conditions were met. Among them: requiring environmental reviews to ensure that use of state forestland for carbon sequestration would not harm the site's "natural heritage."

Hanger said he would devote himself daily to encouraging passage of the bill, which he hopes will happen this summer so that Pennsylvania can build on its five-year-old portfolio standards.

"We're at a juncture now where we're either going to build on that foundation," he said, "or actually run the risk of seeing it wither over time."

Contact staff writer Diane Mastrull at 215-854-2466 or dmastrull@phillynews.com.