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).
Gail Combs says:
January 11, 2014 at 5:43 am
Socialism is the preferred politics of bankers and the corporate elite. E.M. Smith explains why HERE.
http://chiefio.wordpress.com/2011/03/14/forget-gen-x-now-its-generation-hot/#comment-14483
Gail,
Thanks for that link. That’s an especially compact summary of how the US is being driven and led deeper into socialism. E.M.Smith succinctly summarizes the depth and breadth of the creeping socialism that most of us uneasily sense and catch glimpses of …but struggle to put the pieces together into a coherent and comprehensive picture.
Mac
The new coal plants are VERY clean. The major issue here is that while coal and natural gas can be used, natural gas is MUCH better used for heating in your city. NG is easy to distribute as compared to coal hoppers everywhere. And the major capital required for coal to make them burn clean is available on a large scale for electric generation but NOT for heating in your home!
It makes LITTLE sense to burn up natural gas for electricity when we have coal. If we burn too much natural gas then the cost of home heating goes up SIGNIFICANTLY AND this hurts fixed and lower income people.
SAVE the natural gas for home heating and KEEP the costs down that will result in millions of people paying LESS for that natural gas.
Using more coal means keep the NG heating costs down for millions of consumers that now rely on affordable natural gas. Natural gas is MUCH better for home heating.
Coal is much better for electricity and as noted really does not pollute with modern equipment anyway (assuming people here see CO2 as beneficial plant food).
MOST important is using both products to keep natural gas costs down.
Most consumers and buildings in cities now much rely on natural gas for home heating – they cannot switch to coal.
Producers of electricity can use coal and should do so BEFORE choosing natural gas. Choosing natural gas based on co2 output is brain dead – the result will be many more people becoming “poor” due to rising natural gas costs.
CD153 says:
January 11, 2014 at 9:40 am
Based on everything I’ve read in the above comments, I believe I can see power blackouts in this nation’s future with the huge costs to the economy to go along with it. If and when it happens, it seems quite clear that the EPA and Obama will be to blame. The idiocy of ill-conceived and poorly thought out government regulations and agendas will get you every time.
And the worst part of it will probably be that the MSM in this country will blame anybody but Obama and the EPA for it.
+++++++++++++++++++++++++++
If it is any consolation, our idiots in government in Britain are engineering the same situation. We are closing our coal-fired power plants, by order of the EUSSR, belated thought being given to what will replace them. We also face the prospect of rolling blackouts next winter. Germany, meanwhile, is building more coal-fired power stations to keep the lights on. It seems the same rules do not apply to all.
Mac the Knife says: @ur momisugly January 11, 2014 at 9:57 am
…
Yes E.M. Smith gives the best explanation I have ever seen. That is why I have it book marked.
albertkallal:
I write to support your post at January 11, 2014 at 10:07 am.
Gas can be piped so is easily distributed to points of use when used for heating buildings. This is very efficient because all the heat from burning the gas is then used for the heating. All the gas is used.
But the best CCGT gas-fired power stations operate at ~60% efficiency. So, the effect of using the gas to generate electricity is similar to throwing away more than a third of the gas.
Richard
Gail see this about Mercury.
http://www.sciencedaily.com/releases/2008/06/080629081932.htm
You need to specify whether it is ‘failure of the grid’ or ‘rolling (forced load shedding) blackouts’ in such conjecture; the two are not the same.
One involves wide-spread loss of (1) generation (due to protective circuits in generation stations tripping out because the system became unstable for a multitude of reasons) and the other (2) involves ‘planned’ shedding of load(s) via substations selectively cutting off various distribution circuits for pre-determined periods of time in a ‘share the pain’ program out amongst the ‘load’ (the electricity consuming public) …
.
Perhaps one does not recognize the energy consumed in running required ancillary equipment, such as fans, compressors, friction losses in the turbine including ‘air’/gas turbine compression losses, misc. heat losses etc. There are unavoidable ‘losses’ (which sometimes turn out to be required ‘processes’ e.g. the energy required in a gas turbine to ‘compress’ the incoming air or in a coal plant the required coal-feed conveyor belts, air-feed fan system, etc) no matter the generation system.
.
A case study for this is the cold snap in the Southwest (incl. Texas) in February of 2011, where gas pressures dropped so low of the consuming public that gas-powered furnaces failed to function.
Beginning on page 9 are detailed the problems seen on the ‘gas’ supply side (processing and distribution) due to the cold snap:
“Report on Outages and Curtailments During the Southwest Cold
Weather Event of February 1-5, 2011”
http://www.ferc.gov/legal/staff-reports/08-16-11-report.pdf
.
_Jim:
My post at
Your post at January 11, 2014 at 11:05 am replies to that saying
Perhaps you don’t have a clue what you are talking about.
Either that or you lack ability at reading comprehension.
Pumping gas along distribution pipes does need compressors but their operation is more than accounted in my saying “more than a third”.
And I don’t know of any home heating system which uses e.g. “turbines” and there are no heat losses from the heating system when it is inside the house.
Richard
Why would we prevent warming, unless it really is going to be extreme? The most prolific eras of paleohistory were sitting at about 10°C warmer than now. If we were in danger of causing a sudden shift to that level, the disruption would be considerable for a while, but there’s no sign of such video game-style “tipping points”.
Prepare for cooling, and pray it doesn’t happen.
Maybe I’m missing a few points here, but…
My observation (having been involved some years back around the operations end of a utility that operated gas-fired and nuclear generation but no coal, though we did have other industry data) was that – apples to apples – natural gas plant O&M was considerably cheaper than coal-fired. The fuel-handling equipment was nugatory compared to all the conveyors, pulverizers, etc., you didn’t have mine debris turning up in the equipment, the fuel quality was consistent and easily measured and so burner operating conditions were easier to control.
So even an old coal-fired generating unit that’s long paid off its capital cost likely still has significantly higher maintenance expenditures than a comparable gas-fired unit even before you talk fuel cost, emissions retrofits, etc. Of course, a combined-cycle plant introduces additional machinery complexities and a learning curve for the company and its staff and contractors, which may or may not impact its availability and O&M cost.
Every sort of system you can envision has losses. If you’re burning gas for heat in a building, any heat that goes out the flue is lost potential energy. If you’re heating water and using that water for heat, then any heat that water gives off to the surrounding air or other materials in non-living spaces is lost. At the same time, if you are implementing a separate and parallel infrastructure (e.g. gas pipelines, distribution facilities and low-pressure distribution piping) the cost of building and maintaining that infrastructure is also ‘waste’ that needs to be factored into any comparative calculation. Use of electricity for area heating is generally quite inefficient, but it can be ‘targeted’ to small applications better than most other forms.
Very interesting post. The paper itself seems to deserve the “ho-hum” reaction it got. The discussions of the economic and technical aspects of using natural gas fueled gas turbines was much more interesting.
In that regard, Richard Courtney’s comments should be very helpful to those not familiar with peaking and combined cycle use of gas turbines.
But IMO the prize for the “take-way” comment should go to David L. Hagen:
David L. Hagen says:
January 11, 2014 at 7:17 am
“Beware the Red Queen with dangerous dependency
Natural gas is particularly prone to major price increases and price spikes. “
The graph he references only goes back to 1983. at $3.97 per 1000 cubic feet. Only 12 years before, in 1971, the San Antonio electric utility, (now called CPS Energy) had a long term contract for natural gas at less than $0.30 per 1000 cubic feet.
David’s final sentence says it all for me:
“Demanding we move off coal to gas is the height of foolish political correctness that will make us dangerously dependent on unreliable natural gas.”
JEM:
re your post at January 11, 2014 at 12:21 pm.
Yes, of course, as you say, the competitive cost of any plant or system is unique so needs to be individually evaluated. But that is not what we are doing – or could do – in this thread.
In this thread we are discussing overall effects.
CCGT is clearly the most economic choice for new power generation plant at present.
But it seems extremely unlikely that in general new CCGT provides cheaper electricity than old PF which has payed-off its capital cost. That is certainly not true in the UK. If it is true in the US then I would like to see the evidence.
Also, I have not yet obtained a reply to my above question; viz.
But you seem to be suggesting the coal-fired plants are being scrapped to be replaced by CCGT because the CCGT plants are so much more competitive than existing PF that this is economic. Frankly, if you are suggesting that then I need much more information to be convinced of it.
And I challenge you to demonstrate that using gas for space heating is more energy efficient than using it for space heating. Frankly, unless pipe leaks are ridiculously high, I don’t think that is possible.
Richard
Ouch. I’ve done it again!
I wrote
And I challenge you to demonstrate that using gas for space heating is more energy efficient than using it for space heating
Of course, I intended to write
And I challenge you to demonstrate that using gas for electricity generation is more energy efficient than using it for space heating
Sorry.
Richard
I can only read what is posted, Richard, not ppl’s minds …
When Richard says: “But the best CCGT gas-fired power stations operate at ~60% efficiency. So, the effect of using the gas to generate electricity is similar to throwing away more than a third of the gas.” he must not be cognizant of of the energy budget in a turbine, specifically, what the energy requirements to compress ‘air’ in the 1st, 2nd , 3rd etc compressor stages en route to the combustor … That energy is part of the CODB (cost of doing business) in a gas turbine. Not all of the 1/3 of the energy not seemingly utilized is simply a pure ‘waste’ product.
.
_Jim:
I strongly suggest you go to an elementary school to learn how to read.
For the third time, THERE ARE NO TURBINES IN HOME HEATING SYSTEMS.
The gas is burned in the home to provide the heat. THERE IS NO TURBINE.
Richard
richardscourtney says:
January 11, 2014 at 1:47 pm
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Perhaps not a turbine but there is a fan. That’s why they call it a “forced-air” natural gas furnace. Without a fan you can’t distribute the heat throughout your home. The furnace burner will not ignite (not the pilot light, which is always on – the main burner).
richardscourtney says:
January 11, 2014 at 11:50 am
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There are real heat losses from a home heating system. It occurs during the delivery of the heat to the entire home. The result is some rooms (often those closest to the furnace) are over-heated relative to others (usually those the furthest away from the furnace). The result is the thermostat is increased to produce the desired warmth in the areas where the house is used most (e.g. kitchen).
Heating loss within a home due to improper sealing of the ductwork can be significant, especially in modern homes where they use thinner walled ducting and often don’t seal the connections. The problems with older homes are poor insulation, lack of vapour barrier and drafts around windows and doors.
Steve from Rockwood says at January 11, 2014 at 2:28 pm…
Quite true and well said.
But the question being addressed was between using gas in a power plant to make electricity or burning it in the home.
The issues you raise would affect domestic heat in the same way, whether the heater was electric or gas. The 30%-40% inefficiency has already happened at the power plant before the issues you raise affect both forms of domestic heat generation.
Jim says:
“You need to specify whether it is ‘failure of the grid’ or ‘rolling (forced load shedding) blackouts’ in such conjecture; the two are not the same.”
I apologize Jim for not specifying the type because I am not an engineer. I was however referring to those situations that I recall hearing about where the grid gets overloaded with demand for power. I was thinking that this could happen in the future due to the shutdown of the coal plants without any immediate replacements for them (if that makes any sense to you.)
I would appreciate any enlightenment on this that you could provide on this. Thanks.
Steve from Rockwood:
Thankyou for your comments at January 11, 2014 at 2:10 pm and January 11, 2014 at 2:10 pm.
Firstly, yes, technically a fan is a turbine but it is not a gas turbine CCGT as _Jim keeps discussing.
Indeed, any energy expended to operate the fan is released as heat within the heated building so is not lost.
Secondly, there will be some loss of heat up the flue when using gas to heat a building, and this is true loss from the heating system. More important is gas leaks in the gas supply to the building.
Any heat lost from the building is a problem with the insulation of the building and is not a loss from the heating system itself. The loss would be the similar however the building was heated.
None of this affects the simple truth of what I said; i.e.
In other words, given the choice of using gas for home heating or to generate electricity then choosing to generate electricity is – in effect – throwing away a third of the gas. That is true.
Richard
In a self-contained natural gas (actually propane) home heating system the propane is in a pressurized tank and does not require a pump or electricity to flow. If you have a propane stove you can cook without power but you have to manually start the burner (with a match). You can’t use the oven without electricity, however, because the burner is enclosed and operates on a temperature sensor. But, if you lose power you can pull your stove away from the wall and connect the 110 VAC cord (in Canada) to a small generator and cook yourself a turkey (which we did this Christmas). This is tougher on an electric stove which needs more electricity. A propane stove probably needs about 700 Watts peak.
The problem with self-contained propane for heating is the electric fan requirement in the furnace to distribute the heat. There are propane-fired generators but their cost of use is reportedly three times diesel, which itself is about 3-4 times what you pay for delivered electricity from the grid.
I always felt that the people who deliver your electricity know how cheap it is and so they come up with other schemes to increase the rate knowing you will not switch off-grid. I pay a “delivery fee” for my electricity that is almost the same as the cost of the electricity. And it’s still cheaper than being off-grid (in cold Canada).
richardscourtney says:
January 11, 2014 at 2:45 pm
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Sorry Richard. That was too fuzzy for me. Given the choice of using gas for home heating (in Canada natural gas is far cheaper than electricity for this purpose) or to generate electricity then choosing to generate electricity (?). I think you mean delivering gas to a house and then using that gas to generate electricity. That is very inefficient. Many people also take electricity and then use that to generate heat – also very inefficient.
The cheapest method in Canada (generally) is to heat with nat gas and take your electricity from the grid – even if you have to grab some ankle.
Steve from Rockwood:
Sorry, but your post at January 11, 2014 at 2:49 pm changes the subject.
Your information on a “self-contained natural gas (actually propane) home heating system” is not what was being discussed. Your information is useful and I know its importance because some rural areas here in Cornwall are not on the distribution system for gas and dwellings in those places use such systems.
At issue was the difference between using piped natural gas (methane) to buildings for heating or using that gas as fuel to power stations which generate electricity.
But the information you provide is interesting and may be useful to some.
Richard