It appears that an enormous contribution to global warming is from Electric Power Generation Plants! I was very surprised at finding that, because they seem to be "under the radar" where many people consider electricity to be "part of the solution" and not really "part of the problem". It may be necessary to re-evaluate our attitudes toward such large issues!
Many people, especially politicians, seem to think that Nuclear power plants are a very attractive "solution". President Bush and Congress seem to want to start construction, and reduce safety requirements, on a hundred or more new new nuclear power plants! It is hard to see who does the thinking regarding such things! EVERY Congressman has a paid staff of around 400 people, many of whom are supposed to research and provide accurate information for that Congressman. Such people don't seem to do very good research! They don't seem to be aware that the US had essentially mined all the Uranium in the US long ago (by the mid-1990s) and that there have been NO Uranium mines in the US for many years! (We IMPORT around 92% of the Uranium used as fuel in our own current nuclear power plants, with the remaining few percent coming from re-processed nuclear warheads, which we had mined long ago! There is NO nuclear fuel in America to supply a hundred ADDITIONAL nuclear power plants, because there is none to supply the existing ones!)
The World Almanac (and other sources) say that during 2003, the 99 operating nuclear power plants in the United States SUPPLIED 763,744 MKwh of electricity. Since one Kwh = 3412 Btu, this is the same as 2.605 * 1015 Btu. The same source(s) indicate that the U.S. CONSUMPTION of nuclear fuel in 2003 was 7.97 * 1015 Btu. It is also stated that nuclear power plants supplied 19.8% of the total electricity in the US in 2003.
We can calculate several things from this information. First, the nuclear power plants had an average operating efficiency of 2.605 * 1015 Btu / 7.97 * 1015 Btu or 32.7%. This number might sound low but it is due to the many processes involved in converting nuclear power to steam, then to rotary power in steam turbines, and then into electricity in spinning alternators. (Much of the heat that is lost is actually INTENTIONALLY dumped! Once the steam that was created has driven the turbines [once] it is sent to a cooling tower, to evaporate a lot of water and send amazing amounts of heat up into the atmosphere!)
Given this data, we can also calculate that the TOTAL SUPPLIED ELECTRICITY in 2003 was 763,744 / 19.8% or 3,857,000 MKwh, or 3.857 * 1012 Kwh or 13.161 * 1015 Btu. We will use this number later.
The greatest efficiency losses are due to the massive amounts of 1000°F steam which is no longer needed or wanted once it has driven the steam turbine [once], and huge cooling towers (and many equivalent devices) then "get rid of" the remaining heat to cool the steam back down to being just warm water. For many years, all that heat was transferred into hot water that was sent out into rivers and lakes, but that was found to cause massive biological growths and other environmental hazards. When that method of dumping their excess heat was no longer allowed, they still had to get rid of the heat, so virtually all of that waste heat was transferred to the atmosphere, through the cooling towers, etc. There was apparently an ASSUMPTION that there were no bad effects that would result. Since the air was generally quickly carried away by winds, that appeared to be the case. The single exception was regarding power plants that used "high sulphur coal" which came to be criticized for creating "acid rain" since the sulphur dioxide they emitted [from their smokestacks, another large source of heat and here also pollution, sent up into the atmosphere] combined with water vapor to create (fairly weak) sulphurous and sulphuric acids in the air. But little other criticism seems to have been directed toward electric power generating plants for many years.
Most Electric Power Generating Plants (in the U.S.) are set up to use coal as the fuel for producing steam for the turbines/alternators that produce a constant amount of electricity, along with other [spare] alternators that are normally not running. This makes it so that around 50.8% of the electricity generated in the United States is produced from burning coal.
These other alternators are generally powered by modified airplane jet engines that use natural gas or (refined) petroleum as the fuel source. Those jet-engines/alternators have lower efficiencies, usually in the low 20% range, and so they are usually not relied on as the primary electric power generators. Their advantage is that they can be started and generating electricity within a few minutes of a required power demand surge. This allows the main coal-fired generators to be smaller than would otherwise be necessary. In any case, such plants use a combination of coal, natural gas and petroleum products as fuel, with coal being the major component and the other fuels varying depending on demand surges. In 1999, coal was burned to produce 50.8% of the electricity in the United States, with another 15.4% being produced by burning natural gas, and another 3.3% produced by burning petroleum products. This means that a total of 69.5% of the electricity produced in the US was from burning fossil fuels.
The point here is that each of those technologies have the same large thermal losses as for the nuclear fuels mentioned above. For coal, the overall thermal efficiency is comparable to that calculated above for nuclear, in the lower 30% range, for the exact same reasons, but lower due to several percent of additional losses due to inefficient burning. For jet engine driven alternators, the thermal losses due to heating water to create steam and then discarding that waste heat are avoided, but the jet engine exhaust has enormous amounts of heat in it. A jet engine operating at maximum efficiency is around 32% efficient, with the rest mostly getting wasted as the hot exhaust gases. There are mechanical losses and then electric-magnetic losses in the alternator, which explains the "low 20% range" total thermal efficiency mentioned above.
There is another source of electric power, that from hydroelectric dams. They are wonderful in several ways, because NO fuel is burned, so there is no contribution to global warming, and the falling water directly drives turbines that drive the alternators, so that much higher overall efficiencies are possible. Unfortunately, we don't have enough mountains! Only around 8.5% of American electricity is generated by hydroelectric power plants. Unfortunately, they also have some very serious problems of their own, such as causing immense amounts of sediment to accumulate under the reservoir in front of the dam (reducing reservoir capacity and interfering with natural processes). There is also evidence that some of the giant dams, such as Glen Canyon Dam (in Arizona) have a lot of water seeping through the soft rock AROUND the dam. This is clearly weakening the attachment of the dam to the rock, and seems to imply that possibly within 20 years, there is danger of that entire dam breaking loose and falling over! If that 600 foot tall dam breaks, the immense amount of water and sediment in the reservoir would them devastate everything downstream, a true disaster.
Given that hydroelectric plants only supply around 8.5% of our Nation's electricity, and there are no remaining large rivers that could have additional dams built, we will focus on the 90% of electric power generation that produces large amounts of atmospheric heating [from fossil fuels and nuclear fuel]. From the comments above, the net thermal efficiencies of those methods (using nuclear, coal, natural gas and petroleum products) is all in the general area of 30%. This means that of the (100%) power created from the fuel, 30% winds up as electric power leaving the alternators. And as calculated above, the TOTAL amount (in 2003) was 763,744 / 19.8% or 3,857,000 MKwh, or 3.857 * 1012 Kwh or 13.161 * 1015 Btu. Ninety percent of this is 11.845 * 1015 Btu. THIS is the amount of electricity generated, in other words, 30% of that in the source fuels' heat.
Isaac Newton said, among other things, that energy must be Conserved, it cannot be created or destroyed. This is very well established. So, the point here is, what happened to the OTHER 70% of the heat from the fuels' heat? Well, since it cannot be destroyed, it must all still exist, but as OTHER types of energy. It turns out that nearly all of it is converted into heat that gets released into the atmosphere. The numbers above tell us that in 2003, that was 27.64 * 1015 Btu of waste heat from electric power plants that was intentionally dumped into the atmosphere!
This is an incredible amount of heat to put into the atmosphere! 27,640,000,000,000,000 Btu!
For comparison, let's look at heating homes in winter. In a cold climate like Chicago, a medium-sized house uses up around 50 MBtu in an entire winter for heating (Forty million usually gets used to heat the house [which later gets wasted into the atmosphere through the insulation] with the other ten million lost in the the exhaust gases up the chimney.) There are around 40 million homes (families) in climates like that, so the TOTAL amount of heat that they all contribute to the atmosphere is around 2 * 1015 Btu.
Please note that ALL those millions of residential houses contribute a tiny fraction of the heat WHICH IS INTENTIONALLY DUMPED into the atmosphere from the Electric Power Generating Plants!
The power plants are putting around 15 times as much heating into the earth's atmosphere as ALL the houses and apartments in America together!
Let us consider automobiles and trucks. There are over 130 million of them registered in the US and regularly on the roads. There are around 120 million drivers and they drive an average of around 12,000 miles per year (using an average of around 700 gallons of gasoline each). (these are figures available from many government and industry sources). A gallon of gasoline has about 126,000 Btu in it and the best modern cars have around 23% thermal efficiency (or 77% gets wasted, mostly as engine and exhaust heat, air friction, tire friction and other modes of heat). (the AVERAGE thermal efficiency of all vehicles on the road is probably lower than that, maybe around 20%, due to lack of maintenance and the many older vehicles on the roads, but we will be generous here). Multiplying all of this tells us that they collectively send (1.2 * 108 * 700 * 126000 * 0.77) or 8.15 * 1015 Btu into the atmosphere. That is much more than from all the home heating, but not even close to the total amount of heat which is (mostly) INTENTIONALLY dumped into the atmosphere from the electric power generating plants.
| coal | 6.684 * 1015 Btu |
| natural gas | 2.026 * 1015 Btu |
| petroleum | 0.433 * 1015 Btu |
| nuclear | 2.607 * 1015 Btu |
We can confirm the accuracy of all of this. There is an alternate way to calculate these things, by considering the actual amounts of fuels consumed, such as the 1,071,753,000 short tons of coal of which nearly all was burned up in electric generating plants. The World Almanac also tells us that in 2003, that coal CONSUMPTION was equal to 22.31 * 1015 Btu. When burned at 29.95% net thermal efficiency (to produce the known amount of electricity indicated above), that means that 15.63 * 1015 Btu of the total heat losses above came from the coal that was burned, which numbers closely agrees since coal-burning in power plants creates around 50% of our electricity and this amount of loss is 15.63 / 27.64 or 56% of the total calculated above. This represents an additional confirmation of the validity of these figures and this analysis. Note also that we have confirmed that the net thermal efficiency of the coal burning electric power generating plants is just under 30%. Actually, there are many additional losses in getting that electricity to distant homes, and the net electricity actually received at our electrical outlets is only around 13% of the original energy in the fuel! Sad, huh? (most of that additional 17% of energy loss is due to the long high-tension electrical lines that carry the electricity the many miles from where a power plant is to where you are. Since those wires carry very high electrical currents, and they have unavoidable electrical resistance, there is an unavoidable power loss of I2R. Essentially, all those long power lines act much like the wires in your toaster do, to get hot and radiate away heat. Conventional design of such high-tension lines is such that they INTEND that only 90% of the electricity put in one end of a 60-mile long high-tension line actually comes out the other end, and all the rest goes into heating the atmosphere around the wires!)
We had already calculated above that nuclear power plants had an average net thermal efficiency of 32.7% in 2003, in the same general ballpark. The lower thermal efficiency of the jet turbine engine-alternator installations cause their actual production cost of the electricity to be around three times as high as with nuclear or coal, which is the primary reason that power plants do not use natural gas or petroleum any more than necessary! It is ONLY the rapid start-up capability of the jet-turbine engine, and their relative cheapness regarding installation costs, where additional electricity can be produced within a few minutes for load surges, that even make such machines desirable at all.
But that technologies have already long existed that could greatly improve the thermal efficiency of (thermal) power generating plants. And the better the efficiency, the less heating of the atmosphere will result.
Note that if even a 7% improvement (reduction) in the heat given off by power plants were accomplished, it would be a greater improvement regarding the actual heat contributions toward global warming that in ALL the homes, apartments and businesses in the United States all turned off their winter heating furnaces! (Global warming has a far greater contributing effect of pollution and carbon dioxide being sent up into the atmosphere, which acts as a thermal blanket in keeping the Earth's surface warmer than we are used to, a situation not discussed here but in a different associated web-page linked below).
Well, it is still true, and now far more important! Twenty-five years ago, I described mundane technologies that could gain many, many, many more megawatts of power from (coal/nuclear) power plants, with many GOOD consequences! I hope the owners of such plants eventually figure it out!
The current approach, and also the improvement I described to my fellow Physicists around 1980, are all one-pass approaches, where steam is heated, and used to drive turbines, and then discarded as waste.
At the time, I also mentioned that the still-hot steam might also simply be re-cycled and re-circulated. THEN far less fossil fuel heat would be necessary to re-heat water/steam that was already very hot, rather than discarding it and starting with absolutely cold water to heat up! It really is stupid! ALL houses with central heating systems apply the intelligent approach, where room air is re-cycled and re-circulated through cold-air ducts back to the furnace to be re-heated. In that way, the house air only has to be heated from say 65° to 100°F, rather than always bringing in outside air at 0° to have to heat to that desired 100°. ANYONE can see that THREE TIMES the actualy heating, and therefore three times the heating fuel would be needed for such a one-pass home-heating approach. That actually was popular 80 years ago, but virtually no one still uses it today because of this great difference in how much fuel is needed. So why do all modern electric power plants still use an approach that we all know is completely stupid?
BOTH of these methods of improvement would be expensive to install, true. The low-pressure-steam turbines are a well established technology, but they are large and expensive. But why doesn't anyone see that the massive amount of extra electricity which would then be produced by each power plant, from heat that would otherwise be thrown away, would make them lots of money? As to re-circulating the water/steam, there are aspects to that technology that would need to be refined, for that specific usage, but it should not take long or cost much to do such R&D.
It is rather frustrating to have tried to get people's attention more than 25 years ago about the simplicity of GREATLY increasing the overall performance of our electric power generating plants, but no one seems to listen and no one seems to care! Even now, 2007, things are not yet that different. People (in power) now seem to be listening (mostly because they are starting to realize that they look bad to the public), but they sure don't seem that interested in actually doing much! EXCEPT for some token efforts that they promote as media events! Their profits and their corporations' reputations and images seem to be all that matter to them! By the time they actually start to DO anything, it seems almost certain that the actual remaining supplies of oil, natural gas and petroleum will essentially be gone anyway, so their (future) efforts and expense will be for naught! Interesting!
(The 'Current Energy Resources' link below gives official government and industry numbers for supplies of all of our fuels, and it is so terrifying that it is nearly unbelievable. How could our leaders never have told us about how bleak our future is certain to be?)
The Earth's Rotation as a Source for Energy
Waste Nuclear Power For Making Electricity And Heat?
The Physics of Efficiency In Electric Power Plants
Individual Ways of Reducing Your Energy Usage
Methods of Storing Energy for Later
How Much Energy Comes From the Sun? And Why is there Global Warming?
How does the Sun create so much energy?
Inventions Which Might Help Deal With Coming Energy Catastrophes
An Invention to Efficiently Make Electricity from Solar
Enormous Heating of the Atmosphere by the Alaska Pipeline
Air Conditioning without Huge Electric Bills and without Freon
A Method of Storing Summer Heat to (Nearly) Entirely Heat a House all Winter
An Extremely Highly-Efficient (and Fast, 200.0 mph) Transportation System for People and Products
The Sophisticated Woodstove I Invented in 1973
The Physics of Wood as a Heating Fuel
Why is the North Pole Heating Faster than the rest of the Earth?
A Possible way to greatly reduce Aerodynamic Drag of Airplanes
( http://mb-soft.com/public/index.html )
C Johnson, Physicist, Physics Degree from Univ of Chicago