A meeting at the U.S. Federal Energy Regulatory Commission’s (FERC’s) Washington headquarters yesterday lived up to expectations that it would be one of the most exciting sessions in the agency’s history. Buttoned up policy wonks, lobbyists, and power market experts showed up in droves—over 600 registered—to witness a discussion of what President Obama’s coal-cutting Clean Power Plan presaged for the U.S. power grid. The beltway crowd was joined by activists for and against fossil fuels—and extra security.

Inside proceedings, about the Environmental Protection Agency (EPA) plans’ impact on power grid reliability, protesters against fracking and liquid natural gas exports shouted “NATURAL GAS IS DIRTY” each time a speaker mentioned coal’s fossil fuel nemesis. Outside, the coal industry-backed American Coalition for Clean Coal Electricity distributed both free hand-warmers and dark warnings that dumping coal-fired power would leave Americans “cold in the dark.”

As expected, state regulators and utility executives from coal-reliant states such as Arizona and Michigan hammered home the ‘Cold in the Dark’ message in their exchanges with FERC’s commissioners. Gerry Anderson, Chairman and CEO of Detroit-based utility DTE Energy, called the Clean Power Plan “the most fundamental transformation of our bulk power system that we’ve ever undertaken.”

EPA’s critics argue that the plan’s timing is unrealistic and its compliance options are inadequate. Anderson said Michigan will need to shut down, by 2020, roughly 40 percent of the coal-fired generation that currently provides half of the state’s power. That, he said, “borders on unachievable and would certainly be ill-advised from a reliability perspective.”

EPA’s top air pollution official, Janet McCabe, defended her agency’s record and its respect for the grid. “Over EPA’s long history developing Clean Air Act standards, the agency has consistently treated electric system reliability as absolutely critical. In more than 40 years, at no time has compliance with the Clean Air Act resulted in reliability problems,” said McCabe.

McCabe assured FERC that EPA had carefully crafted its plan to provide flexibility to states and utilities regarding how they cut emissions from coal-fired power generation, and how quickly they contribute to the rule’s overall goal of lowering power sector emissions by 30 percent by 2030 from 2005 levels. (Michigan has state-verified energy conservation and renewable energy options to comply with EPA’s plans according to the Natural Resources Defense Council.)

McCabe said EPA is considering additional flexibility before it finalizes the rule, as early as June. EPA would consider, for example, specific proposals for a “reliability safety valve” to allow a coal plant to run longer than anticipated if delays in critical replacement projects—say, a natural gas pipeline or a transmission line delivering distant wind power—threatened grid security.

As it turned out, language codifying a reliability safety valve was on offer at yesterday’s meeting from Craig Glazer, VP for federal government policy at PJM Interconnection, the independent transmission grid operator for the Mid-Atlantic region. The language represents a consensus reached by regional system operators from across the country—one that is narrowly written and therefore unlikely to give coal interests much relief. “It can’t be a free pass,” said Glazer.

A loosely-constrained valve, explained Glazer, would undermine investment in alternatives to coal-fired power, especially for developers of clean energy technologies. “Nobody’s going to make those investments because they won’t know when the crunch time really comes. It makes it very hard for these new technologies to jump in,” said Glazer.

Clean energy advocates at the meeting, and officials from states that, like California, are on the leading edge of renewable energy development, discounted the idea that additional flexibility would be needed to protect the grid. They pushed back against reports of impending blackouts from some grid operators and the North American Electric Reliability Corporation(NERC). Those reports, they say, ignored or discounted evidence that alternative energy sources can deliver the essential grid services currently provided by conventional power plants.

NERC’s initial assessment, issued in November, foresees rolling blackouts and increased potential for “wide-scale, uncontrolled outages,” and NERC CEO Gerald Cauley says a more detailed study due out in April will identify reliability “hotspots” caused by EPA’s plan. At the FERC meeting, Cauley acknowledged that “the technology is out there allowing solar and wind to be contributors to grid reliability,” but he complained that regulators were not requiring them to do so. Cauley called on FERC to help make that happen.

Cleantech supporters, however, are calling on the government to ensure that NERC recognizes and incorporates renewable energy’s full capabilities when it issues projections of future grid operations. They got a boost from FERC Commissioner Norman Bay. The former chief of enforcement at FERC and Obama’s designee to become FERC’s next chairman in April, Bay pressed Cauley on the issue yesterday.

Bay asked Cauley how he was going to ensure that NERC is more transparent, and wondered whether NERC would make public the underlying assumptions and models it will use to craft future reports. Cauley responded by acknowledging that NERC relied on forecasts provided by utilities, and worked with utility experts to “get ideas on trends and conclusions” when crafting its reliability studies.

Cauley also acknowledged that they were not “entirely open and consensus based” the way NERC’s standards-development process was. And he demurred on how much more open the process could be, telling Bay, “I’ll have to get back to you on that.”

The challenge from Bay follows criticism leveled at NERC in a report issued last week by the Brattle Group, an energy analytics firm based in Boston. Brattle found that compliance with EPA’s plan was “unlikely to materially affect reliability.”

Brattle’s report concurred with renewables advocates who have argued that NERC got it wrong by focusing too much on the loss of coal-fired generation and too little on that which would replace it: “The changes required to comply with the CPP will not occur in a vacuum—rather, they will be met with careful consideration and a measured response by market regulators, operators, and participants. We find that in its review NERC fails to adequately account for the extent to which the potential reliability issues it raises are already being addressed or can be addressed through planning and operations processes as well as through technical advancements.”

This post was created for Energywise, IEEE Spectrum’s blog on green power, cars and climate