As it was, PJM issued a weather alert to its eight member utilities on Jan. 14, six days before bitterly cold temperatures sent demand for electricity soaring. The cold also strained an electric power system already stretched to capacity from two weeks of freezing weather that included an ice storm.
PJM asked utilities to cancel planned maintenance outages and speed the restart of some units already out for maintenance. It also directed hydro plants to curtail operations and allow water in dams to build up so they could generate more electricity during the worst of the cold spell.
But PJM did not call for immediate conservation measures because it did not want to cry wolf, Balmat said.
"We don't want to declare an emergency every time based on forecasts," Balmat said. "If an emergency doesn't come to pass because the forecasts are not accurate, that would be a concern to many people."
Despite PJM's planning, demand for energy soared, and the system ran short of electricity.
"On Tuesday evening when demand was at its peak, we anticipated it would be a close call, but we didn't expect to get into rotating customer blackouts based on the information we had at that time," Balmat said.
"But a lot of unexpected things happened early Wednesday," he said.
The arctic blast that shattered records throughout the region froze coal piles, causing combustion problems for coal-fired plants. Oil barges got stuck on frozen rivers, forcing oil-fired plants to lower their electric output to avoid running out of fuel. Smaller plants that utilities normally save for emergency situations failed to start up because of the cold.
Then non-weather emergencies forced the shutdown of the large Susquehanna nuclear power plant in Berwick and smaller units around PJM's system.
Utilities were caught unprepared, said Neil Brown, spokesman for Public Service Electric & Gas Co. in Newark, whose coal-fired generating plants experienced combustion problems trying to burn frozen coal.
"Frozen coal is something that hadn't happened in a century," Brown said. ''The weather conditions we faced were extraordinary. I don't know if any procedural changes could have affected frozen coal piles or other problems we faced."
Millions of people from Pennsylvania to Virginia lost power as the power pool began a series of controlled blackouts that were supposed to last 30 minutes each.
From 7 a.m. to 1 p.m. Wednesday, PJM rotated outages in an effort to avoid a more widespread, uncontrolled blackout, Balmat said.
Ironically, at the same time utilities were turning off the lights to customers, some were selling excess energy to other utilities within the pool. Peco and PSE&G were among the utilities with extra electricity.
"As a member of a cooperative, these are the procedures you follow." said Peco spokesman Bill Jones. "Everyone shares the burden. It's been this way for 60 years."
When Peco needs energy during the hot summers, it buys electricity back
from utilities with energy to spare.
Last week, public conservation efforts were successful enough that rolling blackouts were limited to Wednesday.
Jones and Brown said their companies had received few complaints about the outages.
"The response of our customers has been overwhelmingly positive," Brown said.
Jones said Peco has received a few dozen calls from people wanting to know why Peco was selling electricity during the blackouts.
"They don't understand the cooperative arrangement," he said.
Nevertheless, some observers said that while blaming the power companies for the blackouts is tempting, the main culprit was cold weather.
"The story from our point of view is nothing beyond what is superficially obvious: A combination of circumstances, including weather, caught the system flat-footed," said Chip Bupp, an economist with Cambridge Energy Research Associates whose Baltimore home experienced three blackouts on Wednesday.
One circumstance was timing.
PJM is a "summer peaking" system, meaning the demand for electricity is highest in summer, when all systems are running flat out and when repair and maintenance is restricted. In winter, utilities take advantage of slower demand to repair and maintain their plants and equipment in preparation for summer use.
When the record cold blasted through the region last week, several of PJM's units were out for maintenance, and several others experienced mechanical and weather related failures. At the worst, 28 percent of PJM's capacity was off during last week's crisis, far more than the 7 percent to 8 percent that PJM normally expects.
In the next decade, PJM plans to install an additional 5,500 megawatts of generating capacity.
In the immediate future, energy officials said they would review last week's problems to avoid a repeat.