Ohio-based FirstEnergy’s retirements make up 2689 megawatts, or about 10% of total electricity portfolio-wide.

The Bay Shore plant units at Eastlake in Ashtabula, Lake Shore plants in Ohio, the Armstrong Power Station at Adrian in Pennsylvania and the R Paul Smith Power Station in Williamsport, Maryland will shut down by September 1.

“This decision is not in any way a reflection of the fine work done by the employees at the affected plants, but is related to the impact of new environmental rules [under the US Environmental Protection Agency Mercury and Air Toxics Standards],” president and chief nuclear officer James Lash said.

“We recently completed a comprehensive review of our coal-fired generating plants and determined that additional investments to implement MATS and other environmental rules would make these older plants even less likely to be dispatched under market rules. As a result, it was necessary to retire the plants rather than continue operations."

Some of the 529 individuals impacted by the closures will receive severance benefits, and company officials hope to offset the layoff total by offering workers positions at other facilities and work locations.

A portion of the company’s affected employees over 55 years of age will also be eligible for a retirement benefit.

FirstEnergy said regional transmission group PJM Interconnection will be reviewing the plant retirements for any reliability impacts. In the meantime, it is finalizing MATS compliance plans for the remaining coal-fired units it owns.

The company and its predecessors have invested more than $10 billion in environmental protection efforts since the EPA’s Clean Air Act was passed in 1970, and in the last 22 years the company has reduced nitrogen oxides emission by more than 76%, sulfur dioxide by over 86% and mercury by about 56%.

With the half dozen coal-fired plants coming offline, the balance of FirstEnergy’s fleet will use resources that are non or low-emitting, including nuclear, hydro, pumped-storage hydro, natural gas and scrubbed coal units to produce approximately 96% of its power.

The new and aggressive regulations under MATS are just beginning to take their toll; and according to an Associated Press survey released in December, more than 32 power plants – mostly coal-fueled – in 12 US states will shut down and another three dozen could likely be closed.

While the coal industry will continue to feel the pinch of a reduction in demand stemming from the EPA’s rules, the nation’s environmentalist community is calling the latest announcement a “major victory” that will take “out dated plants” off of the grid.

“Today’s news is part of a national trend of clean energy replacing coal,” Sierra Club Beyond Coal campaign senior director Bruce Nilles said.

“The writing is on the wall for the coal industry. With the cost of coal rising and clean energy prices plummeting, coal’s market share is shrinking fast.”

According to a new Energy Information Administration report released earlier this month, the nation’s expected share of electricity generation stemming from coal is projected to drop to 39% in the next 25 years, much less than the 49% share seen as recently as 2007. In addition to a greater need for environmental compliance, it cited continued competition from natural gas and renewable plants as well as a slow growth in power demand.

US coal consumption, it went on to say, is projected to total 20.6 quadrillion British thermal units, also known as quads, in 2025, or almost 10% down from last year's forecast of 22.6 quads. Consumption for 2035 is forecast was also reduced from 24.3 to 21.6 quads.

“Although coal remains the leading fuel for US electricity generation, its share of total generation is lower in [this year’s] reference case than was projected in the [2011] reference case,” the agency said.

“As a consequence, while still growing in most projection years after 2015, total coal production is lower in the [2012] reference case than in the [2011] reference case, with the gap between the two outlooks increasing substantially over the period from 2020 to 2035.”

The EIA said domestic coal production rises 0.3% per year on average from 22.1 quadrillion Btu (or 1,084 million short tons) in 2010 to 23.5 quadrillion Btu (or 1,188 million short tons) in 2035.