PART TWO OF FOUR PARTS
October Chart for U.S. Electrical Power Consumption.
In the first post of this series, I mentioned how these two Bills currently before the Congress are nothing more than a huge new tax, mainly on electrical power, which has become a staple of everyday life. We are told that the intent of the Bills is to reduce the emission of Carbon Dioxide (CO2) Greenhouse Gas. The nature of electrical power consumption is that any reduction in its use because of these Bills will be so small as to not even register. The largest of those emissions comes from the coal fired power plant sector, those plants now all approaching the end of their viable lives. Those plants are now closing, not because of the intent of these Bills, but because of age related problems, as the average lifespan of a large coal fired plant is around 50 years, and the average age of the whole U.S. inventory of coal fired plants is now at an average age of 45 to 48 years. However, the actual Bills, even though we are told is being aimed squarely at those coal fired plants is also aimed at nearly every other sector of electrical power generation, and in this post I am going to show you the first of those ‘secondary’ targets.
The image at left is the current chart for electrical power consumption for the U.S. The chart is from the huge Government site at the Energy Information Administration. This chart is from October Quarter Report and is for the previous 3 months. Click on the image to open it in a new and larger window.
As you can see from this chart, the power produced from coal fired sources is decreasing, down from the 50% level it was at two years ago. While the concentration is on the coal fired sector, other sectors will also be subject to the intent of this bill, the placement of a new tax on those CO2 emissions. In this post I will deal with the largest of those sectors after the coal fired sector, the sector shown in yellow, that being the natural gas sector. What might surprise you is the the renewable sector is also subject to this new tax as well, and this will come as a huge surprise to nearly everyone, as we are told at enormous length how renewable power is so clean. In actuality, the only sectors not subject to the imposition of this new tax on CO2 are the Nuclear power sector and the Hydroelectric sector, producing just over one quarter of all US power being currently consumed, even though every construction has a carbon footprint if truth be told.
That sector in yellow shows the power being consumed from the sector where Natural Gas is used to produce the electricity.
I have often explained the process for coal fired power production. Coal is crushed to fine powder, and then burned in a high temperature furnace. The heat boils water to high pressure steam which then drives a large multi stage turbine which then drives the generator which produces the power.
I’ve briefly explained how natural gas is used to generate electrical power in my earlier ‘Kyoto’ series, and in this post, I will explain in detail how the electrical power is produced.
Before I do that, I need to explain one of the principles of the generation of electrical power.
The amount of power generated is dependent upon the size of the generator. That then dictates the size of the turbine needed to drive it. This then determines how much energy is required to drive that turbine.
The largest of all the generators are those being driven by either the nuclear process or the coal fired process. Both of these processes can generate huge amounts of high pressure steam, hence the larger the turbine, hence the larger the generator. A typical single generator at a nuclear plant can produce as much as 1200MW, and they average out at around 1000MW. This is why it is more economically viable to have two generators at a nuclear power plant, each being driven by its own reactor where the steam is produced.
Robert W Scherer Power Plant. Commons Image. Author 'Antennas'
A typical coal fired plant can also produce large amounts of power, some also around the 1000MW size as is the case with the newer technology coal fired power plants. The U.S. average is around 280MW per plant. Here you need to take into account that a lot of those smaller coal fired plants are at Industrial plants who generate their own power, and there’s no real need for them to generate more than they actually consume, so there are a lot of small coal fired plants out there. Those that supply power to the grids usually average out at around 500MW per generator, and again, it is more economically viable for large coal fired plants to have between two and five generators per plant, and the largest coal fired plant in the U.S. is the Robert W Scherer Plant in Macon Georgia, which has 4 X 880MW generators and produces 3500MW of power, and burning around 30,000 tons of coal each day. The image at left is of that plant. Click on the image to open it in a new and larger window.
Now why I mention this is to then refer you to those renewable power plants.
Wind towers are restricted by the weight that the huge tower can support. There are some really large towers out there that can support large generators, and these can generate as much as 5MW, but the average is around 2MW, slowly rising now as they become more prevalent, because most are being constructed with 3MW nacelles on top of the towers.
Concentrating Solar Plants (Solar Thermal) are also restricted by the amount of steam they can generate, and the largest is around 250MW to 280MW, and even then it will only be running for a maximum of 8 to 10 hours a day in a really sunny place with a constant supply of bright and sunny days. There is no point having a generator the size of a coal fired or nuclear plant (800MW to 1200MW) at a concentrating solar plant because at no time, ever, can enough steam be generated to even turn the thing over, let alone drive it enough to actually produce electrical power.
So then, let’s look at those plants that use Natural Gas to produce the electrical power.
These use a gas turbine engine fuelled by the natural gas. This turbine then drives a generator. The principle here is similar to what you have in your car. The engine ticks over. It drives the alternator (generator) using a belt. While the engine runs, the belt drives the alternator. This turbine is similar to an aircraft jet engine, and be aware that I only use the word ‘similar’ here because even though the principle is basically the same, the engines are quite different.
General Electric H Series Gas Turbine. Commons Image.
The ‘gas turbine’ uses a starter motor to get it moving. The air is sucked in the front, and is then compressed by rows of blades in the compressor. That air is then mixed with the Natural Gas which is ignited in the combustion chamber. The now hot (around 500C to 600C) air flows over more rows of blades, this part the actual turbine. Once the airflow, the natural gas, and the ignition are in place the unit is self sustaining. A drive shaft ( similar to the principle of the belt in your car) comes off the turbine and this in turn drives the generator. A single unit like this can drive a generator producing around 400MW to 500MW for the larger gas turbines. The image at left is of a typical gas turbine used at power plants. Click on the image to open it in a new and larger window.
Cogeneration is a recent process that then utilises the hot exhaust gas from the ‘back end’ of the gas turbine. The hot exhaust gases are used to heat water to steam which drives a small steam turbine. This also then has a shaft connected in conjunction with the shaft from the Gas turbine. This provides an even greater driving force, and allows larger generators to be driven now from two sources, the waste heat from the gas turbine adding further to the efficiency of the unit. Generators producing 500MW to 600MW can now be utilised by this process.
Some units in use in some areas then further use the still hot exhaust to drive air conditioning units, providing cooled, and warmed air, so the process has been even further refined to be as efficient as is possible. This is called Trigeneration.
The advantage of these gas turbines over nuclear and coal fired power plants is that they can be run up to speed, (3600 RPM) very quickly while any changes in those huge lumbering nuclear and coal fired plants are done very slowly and with a lot of prior notice.
That is why gas turbines are used mainly to provide ‘Peaking Power’, at those times when extra power is needed to top up the grids at times of greatest demand. They cannot be used to supply Base Load power, as their inherent design is that they cannot tick over constantly like the coal and nuclear plants can.
There are more of these gas turbine plants in the U.S. than for any other type of plant, and their Nameplate Capacity is actually 30% higher than the total for coal fired power generation. However, these gas turbines only supply around 45% of the consumed power that those coal fired plants supply. This is the efficiency rate I speak of. This is not the efficiency rate of power produced to fuel consumed, but the power delivered compared to Nameplate Capacity. Nuclear power is currently at around 93% efficiency of delivered power rate, coal is at around 87.5%. Solar Photovoltaic delivers its power at around 20%, Concentrating solar at around 25%. and wind is purported to deliver around 30%, but as I graphically showed recently, the whole German total for Wind is currently operating at only 20%. These gas turbine plants deliver power to the grids at a rate of around 25%. This effectively means that they deliver their power for 25% of the time. This correlates back to the ‘Peaking Power’ I mentioned when these gas turbine plants run up to speed quickly to add to the grids when demand rises. These gas turbines are perfect for this. They can be used in short bursts, run up quickly and actually provide large amounts or electrical power. These gas turbine plants can never be used to supply Base Load, as their design not conducive to constant running. A similar explanation might be this. You buy your new car, turn on the engine, run it at maximum revs and then leave it running at that speed all the time, day in, day out, for the number of years that you own that car. They are not designed to be run like that, and neither are these gas turbine plants.
Now we come back to the top of this page, where the new tax will take effect. Even though these gas turbine plants are the ones that actually are being built in recent times, they are also pretty large emitters of that CO2. You are told that these are cleaner burning and emit a lot less CO2 than those coal fired plants, but let’s actually explore that shall we.
They use Natural Gas as the fuel. This gas emits CO2 we are told, but nowhere near the scale of coal fired plants, or so we are told.
For every 1000 cubic feet of Natural Gas burned, an amount of 122 pounds of CO2 is produced.
To produce the electrical power consumed in the U.S. from Natural gas powered turbines, an amount of 6.86 Billion cubic feet of natural gas is consumed in the process, and this is the link to that data, shown at the bottom left and expressed in thousand cubic feet. So, then working that out we now find that 412 Million tons of CO2 is produced in the process.
That’s 412 million tons of CO2 each year, and as more plants are being constructed, then that number will only rise.
The same can also be applied to that smallest of sectors on that chart above, that being the use of petroleum products for the generation of electrical power. Even though that area contributes only 1.1% of the overall consumed power, that is actually quite a high number. The burning of those petroleum based products also produces CO2, and that amount is calculated out to 100 million tons.
The coal fired sector produces 2.8 Billion tons of CO2 each year, but it supplies more than double the amount of power. Even so, this gas turbine sector still produces quite a large amount of CO2 in the overall scheme of things.
So, now you can see that from just these three sectors alone, an amount of 3.35 Billion tons of CO2 is being emitted. that’s 3,350,000,000 tons of Carbon Dioxide greenhouse Gas. Now perhaps you can gain some sort of perspective of how much of of a gold mine this is for a Government. They tell you with hand on heart that they are doing this for the good of the Environment. Electrical power is now a staple of life. It has to be there, day in day out. Any reductions will be minute when compared to the overall 3.35 Billion tons. Both the Waxman Markey and Kerry Boxer Bills designers and those promoting them know exactly what a goldmine this is, and no amount of changing the wording to make them more acceptable will change the fact they they are in fact just a huge new tax on something that we all just HAVE to have. Electrical power just has to be in in place. Woe betide the Government that tries to take away that electrical power. No! That would be political suicide. Instead, they place an added cost on top of it, a cost passed down to you as the consumer, and then they try and give it an acceptable title figuring that no one could possibly argue against the purity of its intent.
So now you can see that even though the intent of these new tax bills may be aimed at the coal fired sector, it is also aimed at this Natural Gas sector as well, and also the Petroleum based power producers too. So now, you can see quite effectively that more than two thirds of all electrical power being consumed is subject to this new tax on CO2 emissions.
In tomorrow’s post, I will show you something that might actually make your blood boil. That same Administration that tells us they are introducing these Bills to reduce CO2 emissions, and that we also now need to shift to using power generated from renewable sources, one of the by products of these same Bills is that this tax will also apply on the very renewable power plants they tout so loudly.
Incidentally, one last thing about Natural Gas. Don’t you just love that title. Sounds so much better than dirty filthy coal, with all the dirty connotations attached to it. Natural gas is in fact, and wait for it ….. Methane, a gas 23 times more volatile than that dirty filthy CO2 that every green thing on the Planet requires to grow.
Makes you think, eh!
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Posted on Tue 11/03/2009 by TonyfromOz
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