Duke Energy is not only the nation's largest electric utility but one of its political powerhouses. Besides the millions of dollars the North Carolina-based company spends on federal and state campaign contributions and lobbying, another tool it has used to get its way in the public policy arena is the American Legislative Exchange Council.

ALEC is an influential group that brings together major corporations and mostly Republican state lawmakers to promote a business-friendly agenda. It is classified as a 501(c)(3) nonprofit but has drawn charges of illegal lobbying and misusing charity laws, since almost all of its funding comes from corporate interests.

ALEC has been involved in efforts to block stricter regulation of coal ash, which is in the spotlight again following Duke Energy's massive spill into the Dan River from a coal ash pit at one of its North Carolina plants. It has carried out this work with the financial backing of Duke, which belonged to ALEC during the height of the group's work to block federal coal ash oversight.

Since then, Duke Energy has been the target of a campaign by environmental, civil rights and democracy activists that called on the company to quit ALEC. Last year the British newspaper The Guardian obtained documents that suggested Duke Energy may have let its ALEC membership lapse in April 2013 amid the uproar over the group's involvement promoting Stand Your Ground laws like the one that came up in the trial of George Zimmerman after he shot and killed unarmed Florida teen Trayvon Martin. However, the company has refused to say definitely whether or not it is still a member.

Contacted about its ALEC membership status this week, Duke Energy spokesperson Chad Eaton said "we do not release each and every group Duke Energy is a member of or involved with since those memberships and sponsorships are evaluated on an annual basis and often frequently change." He also noted that the company is "active in many groups that have a variety of viewpoints but that does not mean that we support all of the various positions those organizations take."

Nevertheless, it's an established fact that Duke Energy was a member of ALEC during the height of the group's efforts to block strict federal regulation of coal ash and held a seat on ALEC's Energy, Environment and Agriculture Task Force. In addition, Duke Energy's position on coal ash is in line with ALEC's, as the company itself has lobbied to block strict coal ash rules and submitted numerous comments to federal regulators opposing strict oversight.

Federal regulation of coal ash became a pressing concern following the 2008 collapse of a coal ash pit at the Tennessee Valley Authority's Kingston plant in Harriman, Tenn. that contaminated the Emory and Clinch rivers. The U.S. Environmental Protection Agency vowed to enact federal rules governing the disposal of coal ash, which contains potentially dangerous levels of toxic metals like arsenic and lead and other health-damaging chemicals. In May 2010, EPA proposed two options for regulating coal ash -- one that would classify it as hazardous waste and impose strict federal regulations, including a requirement that coal ash pits like those that failed in Tennessee and North Carolina be closed, and another option that would treat coal ash as non-hazardous waste and leave enforcement of basic standards largely up to the states.

But the agency delayed issuing a final rule after coming under intense political pressure from the coal industry and power companies, who argued that strict federal regulation would cost too much and stigmatize efforts to recycle coal ash. Following lawsuits filed by environmental groups seeking the final rule's release, EPA recently lodged a consent decree saying it would issue it by Dec. 19 of this year.

ALEC was one of the drivers of the political backlash that slowed EPA from taking action in the wake of the Kingston disaster. Among the actions ALEC took as part of its efforts to block strict federal oversight of coal ash:

* Passed a "Resolution to Retain State Authority Over Coal Ash as Non-Hazardous Waste." ALEC's board of directors approved this resolution, which "concludes that states are best positioned to serve as the principal regulatory authority for [coal ash] as non-hazardous waste." (2010)

* Published "EPA's Regulatory Train Wreck: Strategies for State Legislators." This report took broad aim at the EPA for various efforts to curb energy-related pollution, including the proposal to treat coal ash as hazardous waste. It urges state lawmakers to "get the state on record as calling on Congress to stop this regulatory train wreck." On coal ash specifically, it promoted the "Resolution to Retain State Authority Over Coal Ash as Non-Hazardous Waste" passed by its board the previous year. (February 2011)

* Distributed "Coal Ash Regulation Talking Points." This checklist of claims includes concerns that treating coal ash as hazardous waste would end up "burdening" coal power plant owners and cost utilities too much. (December 2011)

* Called on members to write the EPA opposing federal regulation of coal ash. After environmental groups filed a Notice of Intent to Sue to force EPA to finalize its proposed rule for coal ash, ALEC urged its members to write a letter to then-EPA Administrator Lisa Jackson "about the impacts of the potential regulation of coal ash." (February 2012)

* Published the "Coal Ash Regulation Policy Guide." This guide for state legislators argues that regulating coal ash like hazardous waste would hurt the coal ash recycling industry and prove costly to power companies. It also says such regulation is unnecessary because "coal ash does not have high levels of toxicity" -- a claim that is not supported by EPA data. It urges state lawmakers to take action by introducing model ALEC legislation including a resolution opposing "EPA's Regulatory Train Wreck," the "State Regulatory Responsibility Act," and "Resolution to Retain State Authority over Coal Ash as Non-Hazardous Waste." It also suggests they write "focused, joint letters" to Congress and newspaper op-eds "highlighting the impact of this regulation." (February 2013)

With the EPA committed to releasing its final coal ash rule this year, it will be interesting to see whether ALEC once again ramps up its efforts against strict regulation. Last year ALEC focused its efforts on rolling back state renewable energy standards but was largely unsuccessful. Duke Energy has been generally supportive of North Carolina's renewable energy law.

More recently, ALEC has focused its energy-related efforts on attacking rooftop solar power, which threatens utility profits. That stance is also in line with Duke Energy's agenda: Earlier this year, the company announced that it wants to cut payments to North Carolina households and small businesses that generate electricity from solar panels and feed it back to the grid -- a change that experts say could halt residential and commercial rooftop solar development and slow the transition to a cleaner energy future.