Here is perhaps a new idea for everyone to consider; Super conductors. Specifically high temperature super conductors. Where the conductor maintains it's super conductivity say to at least 140°F. Well above room temperature.
Why are super conductors so important? First off, around half, if not more of the electricity generated is never used. Wasted by the loss in transmission as well as simply not being used. A super conductor (S.C.) would eliminate the vast majority of that loss.
But of even greater importance is the ability of S.C. to STORE enormous amounts of electrical energy. Try into the gigawatt range. Part of the loss is the fact that power plants run around the clock. And that when the demand for power goes down the plant just keeps on turning out full power. It would be fantastic if we could store any of the unused power for latter needs. That alone would save huge amounts of cash.
Now comes the kicker, why don't we have more effort into S.C. development? First consider what is the biggest consumer of petroleum? Not who or where, but what. Transportation. From the personal car to ships, trucks and trains. I believe the percentage is around 70 to 80% consumption. Now ask yourself this: what would happen if just our personnel vehicles were suddenly all electric? What would happen to the oil industry and those countries who's very life blood is the continued consumption of petroleum, were to, well, disappear?
I doubt that is what they would like to happen. And before anyone says that we'd still need to burn some fossil fuel to generate all that electricity, consider this; the area of North & South Dakota and bordering regions has the potential to generate around a whopping 300% of the total electrical needs of the U.S.!! Just that region alone. And there are number of regions that have the potential to generate large amounts of power. Part of the problem though is getting that power from there to where it is needed.
Now I acknowledge there are obvious 'holes' in my conspiracy theory. But there are aspect to consider. One; the oil companies own the supply, and tend to play dirty with competitors. Two; if S.C. were available, a patent is only good for so many years, then anyone can make it. The same applies to countries that basically only exists because of their oil supplies.
Oh, one last thought, if high temp. S.C. were around, could if be possible to capture the power of a lightning bolt? And how much real power are we talking about?
To modulate the grid and supply the power demand, you must have a power generation system capable of being throttled on demand.....which is the problem with wind and solar...they are throttled arbitrarily, which forces the construction of throttled on demand power generation to retain the ability to keep the system in balance. Otherwise, it's brown out time.
Does that apply to all power plants of all types all the time? My understanding is the gas turbine plants can throttle the power output easily? Nuke plants can vary the control rods? Hydro plants can divert water around the turbines?
I have a BSME so I'm familiar with the thermodynamics. But I'm not in the utility business so I'm not familiar with how much the utility can adjust output according to load on the system.
Actually that is part of the problem. You see the turbines must spin at a constant speed to produce the standard 60Hz. And all the generators generating power supplied to the grid must all be in perfect synchronization. Otherwise there are nasty problems resulting. Which means that those turbines all must keep spinning at the RPM round the clock, never slowing down. Even at night when the demand can in some cases be less then half of the day demand.
So where does that 'excess' electricity go? Absolutely no where. That is right, coal, gas, what ever, is "consumed" to generate electricity that goes now where. All because the turbines must keep on spinning at the same RPM. Now if there was a practical way to store that unused power, the savings could be very substantial.
"The practice is to use excess electricity to run a unit producing liquid nitrogen and oxygen – or ‘cryogen’ from right out of the atmosphere. At times of peak demand, the nitrogen would be reheated to a boil – using waste heat from the power plant heat and as needed from the environment. Step one: the hot nitrogen gas would then be used to drive a turbine or engine, generating the peak demand’s ‘top up’ electricity.
Step two: the oxygen would be fed to a combustor to mix with the natural gas before it is burned. Burning natural gas in pure oxygen, rather than air, makes the combustion process more efficient and produces almost no nitrogen oxide. Instead, the ‘oxygen + fuel’ combustion method produces a concentrated stream of carbon dioxide that can be removed easily in solid form as dry ice. Clean, neat and the only effluent would be what’re produced when making the cryogen. Smartly managed with adequate storage, the efficiency could be quite high."
A New Peak Demand Electricity Generation System | New Energy and Fuel
Synchronous AC generators need to run at the same RPM whenever the plant is running, this is true. But they don't need to run at the same power. Then can run at 100% power or 5% power and all still at the same RPM.
There is a grain of truth in what you said as most power plants have an area of best efficiency and they prefer to run within that area to best maximise their profit vs costs. But the area of best $ efficiency can be quite wide with some plants running between 50% and 100% power as demand requires.
Some plants are designed for constant power generation (called base load)and others are designed to handle varying or even intermittant loads (peak loads).
But it's simply not true that power plants have to run at full power all the time and waste fuel. 1; they don't have to run at full power all the time and 2; fuel is not wasted, any fuel they use generates power which is sold to the grid. The amount of fuel consumed per kW generated remains relatively constant.
Currently we have invented materials that permit superconductivity at temperatures below about minus 90F. Finding/making a material that would have a T_c above 140F is in every sense of the word 'invention'. It may conme out of research labs some day but you can't even begin to estimate that date or even estimate the probablility the invention will be made.
Although there are both private and university labs that may be working on the question, these cannot be Manhattan or Lunar Landing efforts. In those cases we had the science, we just needed development. For superconductors we don't have the science. Private lab funding use to come from companies like Bell, IBM or GE where the objective was to develop in-house expertise in any topic that might become 'business important'. Currently that research is curtailed because business executives are shortterm focused by stockmarket pressure. Typically the Dept of Energy or DARPA (most likely under its newer name) funds some of this research in $25 to $100K university grants. The petrolium industry is no where near that process. In fact today that processes is mostly being constrained by the Republican Party's focus on spending cuts.
I did state that I didn't know all of what is going on. I'm certain that part of that is that some labs do not want to advertise what they are doing for any number reasons. Oh, as for the 140°F temp? That was a 'ball park' figure I used, because it is above room temp, and above most locations on earth.
And TomB, what you said about "not scheduling invention", has got to be a major factor. I wish that there was more available about super conductors for the general public to read. Actual data, not pseudo science, or 'pop' science that is to often found.
RomanLini, I have only basic knowledge of power plants. Including a couple of tours, which includes a local Gigawatt plant. I understand about the use of gas turbines for peak demands. But I would like to know more about just how a generator can 'throttle back' and still maintain 60Hz.
Hi Mark, to answer your question the AC generators run at 60Hz all the time they are running.
If you turn the generator shaft "harder" ie try to turn it faster than 60Hz it stays at 60Hz but current is fed from the generator to the grid.
So you can feed a set amount of positive torque into the shaft which results in a set current being fed to the grid.
If you feed zero torque into the shaft (once running) they usually will "motor" and keep running at 60Hz and drawing a small amount of power FROM the grid.
This is all a gross simplification but generally if you try to turn the shaft faster than sync if feeds power TO the grid, if you try to turn the shaft slower than sync it drains power FROM the grid.
So even though the speed is fixed, the amount of power fed TO the grid depends on the machinery (and how much coal they are burning, etc).
I share your enthusiasm for superconductors too. It's a shame we are such a long way from good room-temp superconductors. And I also agree with you that some new technology for short term energy storage would REALLY open up some new energy options.
I may be a wee bit wrong on this, but if'n you spin a generator at 3,000 rpm, that is 50 hertz or 50 cycles per second....(60 Hertz in the USA) .......there being 60 seconds in a minute, and 50 cycles every second amounts to 3,000 cycles or revs per min....I think this is also dependent on the number of poles in the generator.....a 4 pole genny would spin at 1,500 rpm.....but I might be totally wrong on that.
Generators are load sensitive devices, controlled by the motors that are in turn controlled by a governor.....increase the electrical load on the generator and it acts like a brake, the motor comes on load and the governor senses the rpm drop and increases the power to the motor.......so maintaining the 50 or 60 Hertz frequency standard.
With a governor controlling the motor rpm there can be no excess power produced....the power capacity is determined by the size and output potential of the generator that is trying to pump electrons against the EMF of the grid.
The system of the grid has a back EMF factor, a closed circuit, and when the demand on the grid increases the back EMF falls and so the generator is forced to make more power by increasing the torque produced by the motor.....the rpm stay the same always to maintain the 50 or 60 hetz frequency.
You can see this "phenomena" in the flesh when your car engine is idling and you switch on the headlights to full beam...the engine immediately comes on load from the generator demand and as it's regulated at idle by the carby, fuel injector whatever, it maintains the idle speed by increasing the accelerator position.
In the UK (and probably elsewhere too), I am told the the power plants always had a copy of the TV Times at hand....this was to anticipate the huge load fluctuation that occured at the end and during the TV add breaks when everyone got up to make a cup of tea and flush the toilets etc.
If there is a problem in the efficiency of a power plant, it is not in the delivery system, so when you say "half of the energy is lost" it must be at the plant itself.
Why do I say this? Because the delivery wires are tens [if not hundreds] of thousands of volts, this permits the delivery of electricity to a home with vertually no loss due to heat, as the high voltage all but eliminates current in the wires [which is what generates heat in cunductors].
If there were heat losses in the delivery system of electricity then people would be paying more for electricity they didnt use than electricity they did use, and I don't think that would work.
Also, most power plants have an energy storage system for high demand times, so when high demand hits they can use the energy they stored from generating extra energy during off-times, again increasing the efficiency of the system.
There is certaintly heat loss at the generators that create the electricity, but this heat can often be recaptured and which increasing the systems efficiency [think cogeneration power plant]. Plants with this type of system can reach efficiencies as high as 80%, which is quite good I think.
Yes, there are some plants that have low efficiency, but they don't /have/ to be low efficiency.
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