https://www.scientificamerican.com/article/and-now-the-really-big-coal-plants-begin-to-close/
And Now, the Really Big Coal Plants Begin to Close
Old, small plants were the early retirees, but several of the biggest
U.S. coal burners—and CO2 emitters-will be shuttered by year’s end
By Benjamin Storrow, E&E News on August 16, 2019
When the Navajo Generating Station in Arizona shuts down later this
year, it will be one of the largest carbon emitters to ever close in
American history.
The giant coal plant on Arizona’s high desert emitted almost 135 million
metric tons of carbon dioxide between 2010 and 2017, according to an E&E
News review of federal figures.
Its average annual emissions over that period are roughly equivalent to
what 3.3 million passenger cars would pump into the atmosphere in a
single year. Of all the coal plants to be retired in the United States
in recent years, none has emitted more.
The Navajo Generating Station isn’t alone. It’s among a new wave of
super-polluters headed for the scrap heap. Bruce Mansfield, a massive
coal plant in Pennsylvania, emitted nearly 123 million tons between 2010
and 2017. It, too, will be retired by year’s end (Energywire, Aug. 12).
And in western Kentucky, the Paradise plant emitted some 102 million
tons of carbon over that period. The Tennessee Valley Authority closed
two of Paradise’s three units in 2017. It will close the last one next
year (Greenwire, Feb. 14).
“It’s just the economics keep moving in a direction that favors natural
gas and renewables. Five years ago, it was about the older coal plants
becoming uneconomic,” said Dan Bakal, senior director of electric power
at Ceres, which works with businesses to transition to clean energy.
“Now, it’s becoming about every coal unit, and it’s a question of how
long they can survive.”
Coal plant closures have been a feature of U.S. power markets for the
better part of a decade, as stagnant demand, low natural gas prices and
increasing competition from renewables have battered the coal fleet.
In previous years, most retirements were made up of smaller and
lesser-used units (Climatewire, April 27, 2017). That means the
emissions reductions were less substantial.
In 2015, the United States closed 15 gigawatts of coal capacity, or
roughly 5% of the coal fleet. That still stands as a record amount of
coal capacity retired in one year.
Yet the emissions reductions were modest by today’s standards. The units
retired in 2015 emitted a combined 261 million tons in the six years
prior to their retirement, according to an E&E News review of EPA
emissions data. On average, they annually emitted about 43 million tons
over that period.
Contrast that to 2018, when almost 14 GW of coal was retired. Those
units emitted 511 million tons of carbon between 2010 and 2015. Their
combined average annual emissions rate was 83 million tons.
The trend figures to be even more dramatic this year.
Small plants are gone
The U.S. Energy Information Administration expects almost 8 GW of coal
to retire in 2019, or a little more than half the capacity retired in
2015. Yet the units retired this year emitted more than their 2015
counterparts. Between 2010 and 2015, their combined emissions were 328
million tons, giving them an annual emissions average of 55 million tons.
Other factors are also at play in the retirement of coal’s behemoths. In
some cases, federal air quality regulations or an exodus of customers
may have contributed to the closure, said John Larsen, who leads
power-sector analysis at the Rhodium Group, an economic consulting firm.
The Navajo Generating Station is a case in point. The plant had already
planned to shut down a unit to comply with federal smog regulations. Two
utilities with a stake in the facility had either divested from the
plant or plan to do so. And the plant’s largest customer announced it
could buy power on the wholesale market for less.
“You notice the average size of retired plants going up over time. There
are not a lot of small plants left, period,” Larsen said. “Once you’ve
cleared out all the old inefficient stuff, it’s logical the next wave
would be bigger and have more implications for the climate.”
There are several caveats to consider. Units scheduled for retirement
generally produce less in the years running up to their closure, meaning
the plants that closed in 2015 once emitted more than they did near the
end of their lives.
There’s also this: The vast majority of super-polluters have no closure
date in sight. That’s because massive coal plants generally benefit from
large economies of scale. Because they crank out power around the clock,
their cost of generating electricity is relatively cheap.
“The coal plants remaining have generally installed all the
environmental controls,” Larsen said. “There are no additional
regulatory threats, or they are cost-effective in a world where gas is
$2.50 per MMBtu.”
Another caveat: Coal plant closures don’t guarantee power-sector
emissions reductions on their own. In 2018, power-sector emissions
increased for the first time in many years because electricity demand
rose, prompting natural gas generation to spike (Climatewire, Jan. 14).
But if there is a notable trend with the current round of plant
closures, it is this: The large coal plants closing today are in places
like Arizona, Pennsylvania and Kentucky.
“You’re not seeing climate policy close these plants,” said Mike
O’Boyle, director of electricity policy for Energy Innovation, a
nonprofit that advocates for a transition to clean energy. “Coal plants
are becoming more expensive to operate over time.”
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