From the University of Colorado at Boulder
New study: US power plant emissions down
Power plants that use natural gas and a new technology to squeeze more energy from the fuel release far less of the greenhouse gas carbon dioxide than coal-fired power plants do, according to a new analysis accepted for publication Jan. 8 in Earth’s Future, a journal of the American Geophysical Union. The so-called “combined cycle” natural gas power plants also release significantly less nitrogen oxides and sulfur dioxide, which can worsen air quality.
“Since more and more of our electricity is coming from these cleaner power plants, emissions from the power sector are lower by 20, 30 even 40 percent for some gases since 1997,” said lead author Joost de Gouw, an atmospheric scientist with NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder. NOAA is the National Oceanic and Atmospheric Administration.
De Gouw, who works at NOAA’s Earth System Research Laboratory (ESRL), and his NOAA and CIRES colleagues analyzed data from systems that continuously monitor emissions at power plant stacks around the country. Previous aircraft-based studies have shown these stack measurements are accurate for carbon dioxide (CO2) and for nitrogen oxides and sulfur dioxide. Nitrogen oxides and sulfur dioxide can react in the atmosphere to form tiny particles and ozone, which can cause respiratory disease.
To compare pollutant emissions from different types of power plants, the scientists calculated emissions per unit of energy produced, for all data available between 1997 and 2012. During that period of time, on average:
- Coal-based power plants emitted 915 grams (32 ounces) of CO2 per kilowatt hour of energy produced;
- Natural gas power plants emitted 549 grams (19 ounces) CO2 per kilowatt hour; and
- Combined cycle natural gas plants emitted 436 grams (15 ounces) CO2 per kilowatt hour.
In combined cycle natural gas plants, operators use two heat engines in tandem to convert a higher fraction of heat into electrical energy. For context, U.S. households consumed 11,280 kilowatt hours of energy, on average, in 2011, according to the U.S. Energy Information Agency. This amounts to 11.4 metric tons per year of CO2 per household, if all of that electricity were generated by a coal power plant, or 5.4 metric tons if it all came from a natural gas power plant with combined cycle technology.
The researchers reported that between 1997 and 2012, the fraction of electric energy in the United States produced from coal gradually decreased from 83 percent to 59, and the fraction of energy from combined cycle natural gas plants rose from none to 34 percent.
That shift in the energy industry meant that power plants, overall, sent 23 percent less CO2 into the atmosphere last year than they would have, had coal been providing about the same fraction of electric power as in 1997, de Gouw said. The switch led to even greater reductions in the power sector’s emissions of nitrogen oxides and sulfur dioxide, which dropped by 40 percent and 44 percent, respectively.
The new findings are consistent with recent reports from the Energy Information Agency that substituting natural gas for coal in power generation helped lower power-related carbon dioxide emissions in 2012.
The authors noted that the new analysis is limited to pollutants emitted during energy production and measured at stacks. The paper did not address levels of greenhouse gases and other pollutants that leak into the atmosphere during fuel extraction, for example. To investigate the total atmospheric consequences of shifting energy use, scientists need to continue collecting data from all aspects of energy exploration, production and use, the authors concluded.
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Authors of the new paper, “Reduced Emissions of CO2, NOx and SO2 from U.S. Power Plants Due to the Switch from Coal to Natural Gas with Combined Cycle Technology,” are de Gouw (CIRES), David Parrish (NOAA ESRL), Greg Frost (CIRES) and Michael Trainer (NOAA).
R. de Haan says: @ur momisugly January 10, 2014 at 10:08 pm
…Karl Marx is back: http://www.acting-man.com/?p=27920#
>>>>>>>>>>>>>>>>>>..
OH, an excellent essay.
I especially love
Also do not miss Today’s Reserve Currency = Tomorrow’s Wallpaper
Seems our politicians work for China not the USA.
R. de Haan says: January 10, 2014 at 10:08 pm “Karl Marx is back: …” Karl Marx never left, and is deeply ingrained in the Western reality beyond even economics.
Karl Popper The Open Society and Its Enemies
wayne Job says: @ur momisugly January 10, 2014 at 11:24 pm
Any and every fuel North of an Ice age ice line should be used first, this will give folks of the future south of the ice a chance.
>>>>>>>>>>>>>>>>>>>>.
Now there are words of wisdom!
What idiocy. It is economic suicide to base energy policy on “carbon” emissions. Coal is needed as a base, to help keep NG prices in check. Look what is happening now. With demand for NG up, prices are spiking, and so are electricity prices.
Bruce Cobb says: January 11, 2014 at 5:20 am
What idiocy. It is economic suicide to base energy policy on “carbon” emissions. Coal is needed as a base, to help keep NG prices in check. Look what is happening now. With demand for NG up, prices are spiking, and so are electricity prices.
January 2008 the Prez said:
“The problem is not technical, the problem is not, uh, sufficient mastery of the intracacies of Washington, the problem is, uh, can you get the American people to say this is really important and force their representatives to do the right thing. Uh, that requires mobilizing a citizenry, that requires them understanding what is at stake, you know, and climate change is a great example, you know when I was asked earlier about, uh, the issue of coal, uh, you’ll, under my plan of a cap and trade system, electricity rates would necessarily skyrocket. Even regardless of what I say about coal is good or bad, because I’m capping greenhouse gases, coal-powered plants natural gas plants, you name it, whatever the industry was, uh, retrofit their operations, that will cost money that will be passed on to consumers.”
SOP
george e. smith says:
January 10, 2014 at 10:17 pm
“What the blazes (pun intended) are CH6 and CH12.”
Well, I have be transported on a CH 46 and a CH 53 so perhaps they are earlier, smaller versions.
Doug Huffman says: @ur momisugly January 11, 2014 at 5:02 am
Karl Marx never left, and is deeply ingrained in the Western reality beyond even economics.
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Socialism is the preferred politics of bankers and the corporate elite. E.M. Smith explains why HERE.
Nikita Khrushchev acknowledges that enemy within here:
“You Americans are so gullible! We don’t have to invade you! We will destroy you from within without firing a shot! We will bury you by the billions! We spoon feed you socialism until your Communists and don’t even know it! We assist your elected leaders in giving you small doses of Socialism until you suddenly awake to find you have Communism. the day will come when your grandchildren will live under communism!” ~ Nikita Khrushchev
The words of French Socialist Pascal Lamy former Director-General of the World Trade Organization. He has been tapped to run for head of the EU.
If you use an economic and not a political point of view of socialism and capitalism, Khrushchev and Dwayne Andreas of Archer Daniels Midland Co. are correct. We are ALL Socialists now. (Dwayne Andreas maybe the top all time contributor of campaign funds.)
From that E.M. Smith link:
One big difference between natural gas and coal is that natural gas seems to be a “just in time” type of fuel (being a gas, not easy to store without liquefying it) while coal plants can stock up a big pile of coal that can last for a few months. Weren’t New Yorkers just complaining that the price of natural gas jumped several fold during the cold snap and rate payers are going to have to suffer a rate increase? Do people really want to go to all natural gas electricity for the CO2 reduction if a few cold snaps breaks their local economy?
Mods, two of my comments got booted into the ether a while ago can you fish them out?
Notice, too the tactic of conflating NO and SO2, which are actual pollutants with the fake one of CO2. Those actual pollutants may have been of some concern previously, but with the addition of scrubbers and with the newer plants, not so much.
Here in Ontario the coal plants are all but phased out. I’m waiting for the measureable drop in deaths attributed to coal-fired generating stations.
Two things: One, combined cycle is not a new technology. It was being used on natural gas peaking plants in the 70s and probably before. Maybe there are some improvements, but its not new.
Two, I understand that because of the warm up times associated with the auxiliary boiler and the NOX control systems (you can’t operate the NOX system for a period of time in the warm up), that this technology is not permitted when the natural gas turbine is used for wind and solar backup (instant on and off). That is not a very good explanation, I know. But the point is that natural gas turbines are the technology of choice for backup generation, and combined cycle is not permitted by regulation to be part of that mix. It is far more efficient, as it captures waste heat with a boiler and runs the steam so generated through a steam turbine.
Gail Combs says:
January 11, 2014 at 4:18 am
Gail, the cost of power has several components. Obviously the cost to build and operate the plant, and the cost of distribution infrastructure, are part of the total. However, for all fossil fuel plants, the cost of fuel is the main long term cost driver. Combining fuel as well as other costs for all types of plants typically run ~$0.05 per kW-hr, and this includes coal and gas. Now plants typically run for several decades before major repair/replacement. Using 30 years as typical, a one MW capacity of average use produces 262,000,000 kW-hr of energy, costing over $13,000,000. This energy is sold for about $0.10/kW-hr, for a total of over $25,000,000. Compared to these, the cost of building the plant for $357 per MW is irrelevant. I do not understand where you get the factor of 5 to 10 times, as it is not in the net cost.
I don’t understand where they got their dta that shws 89% electricity production from coal formerly.
Every figure for electric grid production showed around 52% before and now less thn 40%. Since nuclear is always cited as providing 20% of our elecricity, any claims for 89% from coal (not to mention the 11% we supposedly get from hydro) are not fathomable. What exactly are they referring to?
Anthony, I’m at the Holiday Inn off 99 today for a meeting. If it’s convenient for you, it would be nice to say hello in person (you have my email address). I passed through town once going home from Susanville. This is the first time I’m here actually doing something. Nice place. I can see why you like it.
Back on topic, I’m not sorry we are seeing reductions of emissions of mercury, thorium, uranium, and other metals from burning less coal. That said, coal is the one factor historically keeping electrical energy prices low. I remember writing to Bush 43 you can’t have both a strong economy and reduced CO2 emissions (without committing to much more nuclear energy). Here we have another case of the unknown known (extending Rumsfeld), or in the words of Reagan, “It isn’t so much that liberals are ignorant. It’s just that they know so many things that aren’t so.” Apparently, they want us to live a very meager existence, but they don’t imagine themselves doing so. I hope Hollywood is starting to see the connection between low ticket sales, a poor economy, and supporting Democrats. Not that I’m enamored of the current crop of Republicans, at least the national leadership.
Interestingly, the CA legislature had a chance to severely restrict fracking in the state, but not even a Democrat majority would do it. They have only passed a reporting and permitting law (http://www.huffingtonpost.com/2013/09/21/california-fracking-bill_n_3965069.html). I guess even those dodos in Sacto see the economic benefit to the state’s economy, which translates into increased revenue to fuel the bloated bureaucracy, and the eventual benefit of increased campaign contributions from their union minions. Could it be a monetary interest deafens these officials to the screeching and whining from their more radical constituents? Is it possible they could be so self-serving?
@John F. Hultquist. Volcanos emit around 300 million tonnes of CO2 per year (1% of human emissions) according to SkS or more than 130 million tonnes of CO2 every year according to the USGS.
Volcanos mostly emit water vapour and I suspect that both coal-fired and gas-fired plants do too. So if water vapour is a greenhouse gas like CO2, then why isn’t it also a pollutant?
@Gail Combs: The PJM market clearing price numbers sound more like entry prices for peaking plants in their day-ahead market, not baseload pricing. From the link, it appears that this discussion was peaking and that they can do very nicely at that entry price and take capacity payments the rest of the time. A lot of combined cycle natural gas peakers expect to operate <1000 hours per year. Entry prices are all over the map, are node dependent and are mostly set by the producer. For example, the entry price for electricity generation from landfill gas in the PJM varies from ~$35-$70/MWh, depending on node and emissions restrictions. The entry price of diesel generation (peaking) is north of $250/MWh, based on the cost of diesel and other costs.
During the cold snap this week, the PJM hourly prices went as high as $2500/MWh and stayed between $1000-$1500 for quite a while. The price is demand based. It payed to run diesel plants. I've also seen the price at -$1,000/MWh. It made running a stack test very expensive.
The Dept of Enegry statistic I’m looking at, for the US for the year 2011 shows for total electric power production : 4,100,656,000 MW hours and from coal 1,733,000,000 MWhrs, which means 42% of power came from coal. And also 25% from natural gas 20% from nuclear, 8% from hydro.
I still fail to see where that 82% figure for coal came from
Leonard Weinstein says:
January 11, 2014 at 6:32 am
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Interesting statements… do you have links to the numbers you are using?
This article is disappointing in a number of ways. First and foremost it comes from an academic institution that should have higher standards than in the article. They make combined cycle generation sound like something new. Those plants have been around for quite some time. Pollution reduction is mostly “carbon” and with an oh, by the way, NOx and SO2. One has to assume “carbon” (carbon dioxide) is a real pollutant, not a pollutant by regulatory fiat. Also, CO2 emissions by fuel are based on the carbon content of the fuel AND the amount of energy required to generate electricity (aka, heat rate in BTU/kwh). Natural gas wins. It’s heat rate is about 80% of coal and it has a much lower carbon density.
They get to NOx and SO2 reductions as an aside. NOx production is primarily a function of combustion temperature and combustion pressure. SO2 is fuel sulfur content. Natural gas does better on both because you can, if needed, easily scrub sulfur from the gas at a moderate cost. Both generation types will be required to have exhaust NOx treatment, usually selective catalytic reduction, making the NOx emissions about even. Neither can be installed if they result in violating a national ambient air quality standard, even short term.
It should come down to which energy source provides the least expensive energy. According to EIA the O&M costs for coal is significantly less than natural gas combined cycle. The levelized costs are higher. That depends greatly on the regulatory environment and the cost of fuel. Not long ago natural gas tracked diesel and was at ~$12/MMBtu. Due to fracking, it dropped to $2-$4/MMBtu. Natural gas is a much more attractive fuel until the price goes back up.
George e. Smith, you are correct in that methane has the highest hydrogen to carbon ratio in hydrocarbons. Gymnosperm’s words were correct but his formulae were not.
Beware the Red Queen with dangerous dependency
Natural gas is particularly prone to major price increases and price spikes. It tripled from $2.88 in 1999 to about $8.50 in 2008, spiking to $12.48. The present shale gas boom requires a “Red Queen” effect strongly increasing drilling just to maintain production. This makes the whole country exceptionally dependent on an unreliable source with massive consequences of price spikes.
Natural gas is far more valuable for residential and commercial applications where it is difficult to use coal. Demanding we move off coal to gas is the height of foolish political correctness that will make us dangerously dependent on unreliable natural gas.
France is becoming a bigger energy provider in the UK with nuclear plants and now shale gas. In past ages French was the language of our aristocracy – now it is becoming the language of our electricity.
The way I see it (during the time period specified), as the coal power plants aged and the EPA increased the emissions requirement on them, some of the power plants had scrubbers added to them to meet the requirements while others were decommissioned and new plants built in their place because it is cheaper in most cases to build a new power plant to meet the new requirements than it is to outfit the plants with scrubbers. This is why in the next several years (this is what I heard from my neighbor that works for APS) there will be two less coal fired power plants in Arizona with no proposals to replace them. Talk about a lot less power to sell to California.
It seems that this particular article didn’t bother to point out that the switch was due to the increasing emission requirements on power plants and nothing to do with better efficiency of one style over another.
Decommissioning working coal plants is a stupid, greenie-driven waste. These are built to last many, many decades. All long ago had electrostatic precipitators installed (in the US). That had already addressed 90% of any “pollution” concerns.