Skip to comments.Upgrade coal power and cut 15% of emissions. Where is the Green applause?
Posted on 03/26/2013 10:56:42 AM PDT by Ernest_at_the_Beach
If the Greens cared about CO2 theyd be very interested in ways to reduce emissions. But their selective interest speaks volumes about their real priorities. Anton Lang shows how newer coal fired powers stations run hotter and at higher pressures, and use 15% less coal to produce the same amount of electricity. We could upgrade our power stations and cut a whopping 15% of their emissions which is huge compared to the piddling small, often unmeasureable savings thanks to renewables. Even massive floods that stop industry dont reduce our emissions as much as this would. Do the Greens hate the coal industry more than carbon pollution? Jo
Guest Post: Anton Lang (aka TonyfromOz)
It all comes down to steam.
Assume (for a moment) that we have to reduce the emissions of CO2 by something like 20% between now and 2020.
Previously I showed we could achieve a reduction of 13% in CO2 emissions from the electrical power generating sector just by converting from the current 70s technology coal fired power to the newest technology USC (UltraSuperCritical) coal fired technology. That 13% I quoted at the time was theoretical, but in China over the last three years the emissions reduction of new USC plants is even better, around 15% to 17%. This is off-the-shelf technology that handles base-load, produces cheap electricity, and reduces emissions.
The data comes from this link to Shanghai Electric, about a number of plants now in operation for more than three years. Smaller plants of 100MW and less from the 70′s show emissions at 339 grams per KWH delivered. For large scale older plants, emissions are 330 grams per KWH delivered (similar to all (black) coal fired plants in Australia). For this new USC technology, emissions are down to 282 grams per KWH delivered.
Based on the large scale 70s units, these new USC type plants consume 15% less coal, hence emitting 15% less CO2 per unit of delivered energy. For a typical large scale 2000MW+ coal fired plant, that means a savings of 2.6 Million tons of CO2 per year.
The most efficient rotors in a power station are enormous. The rotor in 660MW generator could weigh anything up to 600 tons or more, and that huge weight has to be driven at 3000RPM (for 50Hz power in the U.S. it is 3600RPM, for 60Hz power). Thats rotating that huge weight at 50 times a second. A typical large scale coal fired plant will have up to four generators, each capable of generating between 500 and 660MW. For a typical 70s technology generator, that 660MW is the largest power rating currently in use. It takes a lot of energy to turn something so incredibly heavy at such an extraordinary speed.
Its all depends on steam.
The rotor is the critical part, and more wire loops means more electricity. If you pass a wire capable of carrying an electric current through a magnetic field then a current will be induced to flow along that wire. You will get a larger electromotive force, and thus a larger current flow, if you scale everything up. More wire will give us more current and more power, but then the rotor is harder to push through the magnetic field. Likewise, stronger magnetic fields or higher speeds f rotation also give more power. So in a sense, the heavier, the better.
Place a number of magnetic poles around a shaft, cool the area so the magnetic field is stronger, and wrap those poles in current carrying wire to further intensify the magnetic field. Then add series of these poles along the shaft, and rotate all that at high speed. This is the rotor of a typical generator (in actual fact, a turbo alternator).
This high speed rotor then induces power into the stator, huge amounts of wire wrapped in a shell around, but not touching the spinning rotor. To turn the rotor we need a very large multi stage turbine. To drive that turbine, we need a huge amount of high temperature, high pressure steam. Coal is what boils the water to make that steam.
What makes USC different is the huge amount of high temperature and high pressure steam it can produce.
The critical point of water occurs at 374C at a pressure of 22.1 MPa (3,208 psi), where liquid water and steam become indistinguishable. Above that point (Super Critical and USC), the water does not need to boil to produce steam. So, not only do you need less coal to make that steam, you now also have a saving in water use as well, as it does not need to boil.
The USC units currently in use in China are operating at 600C and 27MPa. In fact China is actively working towards advanced USC, with temperatures above 700C in the range of 760C. Like the U.S., Japan, South Korea and Germany, China have now all but perfected the technology. Originally it was imported, and in cooperation with non Chinese companies, but they are now proceeding on their own. China has already got to the stage where they have a number of plants with units driving 1000MW generators, the first to do so. They are further working towards generators with a capacities of 1200MW and even 1350MW, levels previously thought unattainable even with large scale nuclear power.
This graph shows the steady improvement in electrical power generation. Note the top black line (the MegaWatts size of the plant) is not linear. People were building plants in the 1950′s of 5 10 MW. Now were building 1000MW plants.
Source: USC Technology In China (pdf)
China now has several plants running these large 1000MW generators, usually two at a time, hence 2000MW output.
The ones they already have in operation are running at a CF of 92.3%, something previously only the province of (some) nuclear power plants (page 31 of the above pdf link).
Australia produces about 75% of its electricity with coal, and it amounts to about 27,000MW of power. Our four largest generators are all pre-1975 technology.
What USC technology means is that higher power generators can be used for significant reductions in CO2 emissions, and as the technology moves to the next stage, even less coal needs to be burned to make the immense amounts of steam required to drive smaller generators that produce more power.
And the cost? In China these plants are being constructed for a capital cost of $USD600 per KW, so around $1.2 Billion for a 2000MW plant (page 28 of the above pdf link). In Australia, Bayswater Power Station is planning an upgrade (it is the only one that is) and the cost would be about twice that of China.
So for $2.5 Billion here in Australia, you could get a 2000MW plant of top quality coal fired electricity available 24/7/365. Or you or get a wind farm of 1000MW, with 320 towers, 16% of the power, available far less than 24/7/365.
That ONE generator shown in the top image produces 25% more power in a year than every wind tower in Australia.
So USC is a technology that is sorely needed for the huge amount of cheap power it generates. In addition, it actually lowers emissions of CO2 per unit of delivered energy, and almost by the amount the Government has targeted for 2020. (As if we need to reduce CO2 emissions in the first place.)
Nuclear power plants typically have generators capable of driving huge generators capable of 1000MW+. They can do this because the nuclear process can make huge amounts of steam to drive a huge multi stage turbine, a lot larger than for a large scale coal fired unit. If you were to connect one of those 1000MW+ generators to a 70s technology coal fired unit, it would not even turn, because they could not make the steam to drive the turbine to spin the weight of that rotor.
The same applies with Concentrating Solar Power (CSP). You cannot connect one of those large coal fired generators to a solar plant, because the solar plant cannot make enough steam to drive the turbine needed to make the rotor rotate. You could have square miles of mirrors all focused to the one point to heat the compound to a molten state, which is then used to make steam, to drive the turbine, which drives the generator which produces the power. In fact, the best this CSP can manage is around 250MW, and even that is usually from 5 X 50MW generators. With the enormous added cost of heat diversion so they can (theoretically) generate power for the full 24 hours, they can only make enough steam to drive one of those 50MW generators. The best they have been able to do so far is around 18MW, and even that is not on a year round basis. Averaged over a full year, it works out at around a 66% CF, which equates to barely 16 hours a day. So on perhaps the day with the longest available sunlight in midsummer, it could run through the night and give a full 24 hours of full power, but in winter, even with heat diversion, even these units barely manage 8 hours equivalence at full power.
The short killer summary: The Skeptics Handbook. The most deadly point: The Missing Hot Spot.
The goal is not actual environmental change.
It’s economic warfare based on bad science.
In other words, You pump for pressure and fire for steam temps. Yes, it is more efficient. I would take exception with the saves water statement. even the older tech. recylces the existing water from condenser to feedwater to boiler to turbine and back to condenser. USC water passes through one time but i'm sure not discarded because it must be treated to remove disolved solids that would destroy turbine blading at these pressures. very expensive to treat that much water to those levels of cleanliness, no reason to discard the water under either format. There are many super-critical plants out there
I'll throuh the BS flag on that i'm afraid. Coal-fired UnitsI'm familiar with ran at much higher pressures than the nuke up river could. 2420 Throttle pressure and 1005 degree steam spinning generator at 3600 rpm for 60cycle power. nuke was 1000 throttle pressure and 850 steam temp spinning gen at 1800 rpm for 60 cyles, nuke gen had 4 poles while coal-fired had 2poles When the nuke guys came to visit they were always amazed at the raw power of the facilitymuch greater than they were used to. Clean coal tech works very well. amazing things can be done. May Man-Bear-Pig rot in hell for what hes brought the people. All about self enrichment and not a lick about actual science.
Do we have some in the USA?
Finally a subject on FR that I actually know something about. I taught in and managed our community college’s Power Plant Operator program for several years.
Supercritical power plants are more efficient because of the characteristics of water under various pressures. If you take 32 degreee F water at normal atmospheric pressure and start dumping in heat, you will neeed to add 1 BTU per pound of water to raise the temperature 1 degree F.
In order to get it up to 212 degreees, you have to add a total of 180 BTU per pound of water. Then you have to keep adding heat until you have added another 970 BTUs/pound before the water will turn into steam. That is a total of 1150 BTUs/pound to get steam.
If you pressurize the water to 3206 psi, it takes 903 BTUs to warm the pound of 32 degreee water up to 212 degrees F but it instantly tunrns into steam. No sitting there adding more heat at 212 degrees to eventually turn it into steam.
The 3206 psi water saves you 247 BTUs per pound to get your steam. (1150- 903 = 247)
Where I sit, I could go up on the roof and on a clear day, see the water plumes from five power plants. Two of these are supercritical and have been in operation since the early 1980s. How many pounds of water are in the closed loop for these plants? I can give you an idea from this fact. The 1,300mw plant at one of these five sites only shut downs after a boiler tube water leak exceeds 8,000 gallons per hour. Yes, only when they start losing over 8,000 gallons per hour will they shut down and fix the boiler tube leak.
Yes, we’ve had supercritical plants since the 1980s.
You are correct, nuke plants do not operate as high a temperature or pressure as a supercritical.
By the way, those big shiney pipes in the picture (the ones that look like corrugated bendable pipe) are actually 5-8 inches thick.
The Green movement is about weakening America, not about protecting the environment.
What is the cost of raising the water pressure to 3206 PSI? That would have to be subtracted to get a final cost per unit, wouldn't it?
you are correct in pressurizing the water does add cost in both running the pumps and in the heavier and more costly equipment. Even with this cost, the savings in fuel for a big plant still pays.
I think this is the reason that small plants typically are not supercritical. They don’t burn enough coal to pay for the extra cost.!
I would call that a significant leak,
That is the smaller ones that are less efficient.
What are the economics for the use of Natural Gas....?
Can a plant using the high pressure on water and coal be switched to natural gas....
Assuming a BTU doesn't care where it comes form....loosely speaking.?
Correct. Nuke reactor output temps are in the 650 F range, far lower than a coal-fired plant. Because of that, the steam they produce is highly saturated (i.e. wet steam), therefore requiring much larger multi-stage turbines than the hotter, drier steam from a conventional boiler.
It's not the amount of steam, it is the temperature and pressure of the steam.
Right now, pretty good. But historically, Nat Gas prices swing wildly while coal prices are relatively more stable.
Can a plant using the high pressure on water and coal be switched to natural gas....
If you are asking if a coal fired plant can be converted to a gas-fired plant the answer is yes. Requires new burners and associated systems, but it can and has been done.
But Natural Gas is best used in combined cycle plants (gas turbine-generator followed by a Heat Recovery Steam Generator and a steam turbine) which reach far higher BTU efficiency levels. That is far different than the typical coal-fired boiler arrangement. So economically, it depends on the price of the fuel.
But as far as grid operations, load balance and response time there are other considerations that must be factored in. The grid can not be all one thing or all the other. Different fuels and plants offer their own technical and economic advantages.
Thanks for the reply!
Even in the 1970s we had some. The Mohave station out in Nevada is one I recall from that era as well as Conesville Unit 5 in Ohio... two from that 1970s vintage I have been to. There are others that I can't recall the names off the top of my head.
The Ultra Super-Criticals discussed in this article are using the same concept as the Super Critical units stepped up to even higher in temps and pressures. That was only made possible by the advancements in material sciences (new alloys that can resist those kind of stresses) and advanced control technology (high speed computers) that can respond fast enough to keep the systems stable. Without good controls, you can drop any super-critical plant off line in a few seconds and possibly do a lot of damage to the plant. They have very slim operating margins, sort of like a NASCAR machine vs. our daily drive. ;~))
I retired a few years ago, but I know we were not only working on most or all of the Ultra super critical plants in China but also a few of them in the United States. They are here, but Obama's anti-coal policies will likely prevent us from building more of them. It's a shame too. We have more coal than anyone else, and those Ultra Super Critical plants are efficient as hell.
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