Why are we charged for watts?

[K8MHZ]

Can anyone tell me why we are charged for watts instead of volt-amps?

Now, I'm not complaining, but I am the consumer, not the POCO.

With the proliferation of CFLs and all the discussion about the poor power factor it seems to me that the POCO is not getting paid for all of it's energy. Now, since they can charge what they want to stay in business, I foresee a rate hike to cover the VAR's not being charged for, yet used increasingly as time goes by.

The customer is going to pay no matter what. I think being charged for VA's would be beneficial to all. People are thinking they are saving a bunch of energy by using CFL's. They don't realize that there is more energy (pollution) needed to be generated than it would seem by only looking at watts. If we concentrated on reducing our VA's we would directly be reducing the energy being produced. Reducing our VAR's is also reducing energy being produced that does nothing in return.

Maybe I am missing out on something, but if I was the POCO I would charge for Volt Amp Hours, not Watt hours.

 

[zog]

Simply put, because watts are real power, the energy used to do work, and on the utility end, the power that they produce. It takes more energy to move the prime mover of a generator to produce more watts, it does nto take more to produce VAR's.

VAR's, don't do any work or require energy to produce, they simply assist in producing work such as setting up fields in inductive equipment. Sure there are some line losses from VAR's but they are minor in the big scheme of things. (Trying to keep this basic)

 

[zog]

There is more to your bill than just kWH usage.
-You will find a "Distribution service" that is basically a charge for using thier transformers, power lines, etc... think of it as a toll on a tollway. Included (And by that I mean hidden) is something called DSM that is how they pay for all of those energy conservation programs, like the free CFL's you get in the mail, peak usage programs, etc..
-Your Energy supply service is broken down into 3 parts: Generation (Cost to make the power), transmission (cost of delivery, this is where they put those line losses, including the VAR's I mentioned earlier), and fuel (Um, the cost of fuel). These are demand based and the bulk of your "kWH costs"
-Sales and use surcharge - How they recoup taxes on leased equipment and stuff liek that
-Taxes - Consumption based sales tax and the mysterious "utility tax"

Of course your local POCO may use different terms for some of this stuff but all of the same compoents are there. So don't worry, they have it all covered. As far as your poor PF, you pretty much pay for that based on an average of all the POCO's customers.

 

[K8MHZ]

Simply put, because watts are real power, the energy used to do work, and on the utility end, the power that they produce. It takes more energy to move the prime mover of a generator to produce more watts, it does nto take more to produce VAR's.

VAR's, don't do any work or require energy to produce, they simply assist in producing work such as setting up fields in inductive equipment. Sure there are some line losses from VAR's but they are minor in the big scheme of things. (Trying to keep this basic)

I don't follow you.....

If you have a big enough load and a bad enough power factor, the POCO will charge more for the watts the meter reads. That is why factories utilize power factor correction. Why would they be able to do that if, as you say, it doesn't matter?

Also, if watts and VA's are the same in the eyes of the generation point, why the rating of both watts and VA's on a portable generator?

I still think that the fuel a generation facility uses is based upon the energy produced (Volt Amps) and the actual power being used (Watts).

Now, I know we refer to the utility as the 'power' company, but our utility is named 'Consumers Energy' so semantics don't apply.

If VAR's don't use up energy how can they even exist? I was taught that VAR's consume energy but don't provide working power.

So, do I have to un-learn something? (It happens.....)

 

[K8MHZ]

There is more to your bill than just kWH usage.
-You will find a "Distribution service" that is basically a charge for using thier transformers, power lines, etc... think of it as a toll on a tollway. Included (And by that I mean hidden) is something called DSM that is how they pay for all of those energy conservation programs, like the free CFL's you get in the mail, peak usage programs, etc..
-Your Energy supply service is broken down into 3 parts: Generation (Cost to make the power), transmission (cost of delivery, this is where they put those line losses, including the VAR's I mentioned earlier), and fuel (Um, the cost of fuel). These are demand based and the bulk of your "kWH costs"
-Sales and use surcharge - How they recoup taxes on leased equipment and stuff liek that
-Taxes - Consumption based sales tax and the mysterious "utility tax"

Of course your local POCO may use different terms for some of this stuff but all of the same compoents are there. So don't worry, they have it all covered. As far as your poor PF, you pretty much pay for that based on an average of all the POCO's customers.

We posted at the same time.

OK, here is how I see it. Let's say you have a load with a poor power factor. The watt meter will only record the watts you are using. The poor power factor presents impedance along with additional line losses which, in turn, requires more energy at the generation point than if the power factor was good.

I think that charging for VA's and recording watts would be a better way to monitor and conserve energy use.

Plus it would likely cut down on a bunch of paperwork.

Methinks the system we use today was created before it became the norm for people to monitor energy use with the intent of cutting it down. But that still doesn't explain to me why metering is done in watts, not VA. Maybe it's a public service regulation issue.

 

[K8MHZ]

As far as your poor PF, you pretty much pay for that based on an average of all the POCO's customers.

And this is kind of what I am not liking.

People that have good power factors are paying for those that don't. Thus, there is only a motivation to reduce watts, even at the expense of power factor.

If we were charged for VA's, we would be motivated to reduce those, which would be a much more fair system, and more effective at attaining the goal of total energy efficiency.

But....that may be bad for CFL sales....

 

[zog]

Improving PF has little effect on energy consumption, couple percent at best, you can do better just by something as simple as shutting your computer down at night. Reducing kWH usuage should be the goal. Look at how much we use compared to other countries.

http://earthtrends.wri.org/text/energy-resources/variable-574.html

 

[gar]

101129-1422 EST

K8MHZ:

ZOG provided a good explanation.

Suppose all loads were simply capacitors. No destination work would be done. But there would be a certain amount of power dissipated in the generator, transformers, and distribution wires. This is the only energy the power company has to buy to put in their furnace. This is all wasted because it is doing no useful work. In addition maybe 60 to 70% of the chemical energy put into the furnace is lost as waste heat. Sometimes some energy is extracted from the exhaust steam from the turbines and it is sold as heating energy.

The power company has to have generation and distribution capability for the reactive I^2*R losses in the system. So the goal is to minimize the reactive currents. That is why there are PF penalties for large users. The reactive currents from homes are not as big a problem as from factories. The power company adds some of its own capacitors along the distribution lines to partially compensate for this.

Harmonic currents from capacitor input filter devices (computer and CFLs) are a different problem.

You do not want to and should not pay for VA. VAs are not real energy they are simply a mathematical equation expressing the product of volts measured somewhere and current measured somewhere. Usually the product VA is the voltage across a load times the current thru that load with the voltage and current being correlated with each other. In special cases there may be a simple equation to relate VA to Watts of a load. In other cases no simple equation.

When a motor turns a fan it is doing work. This is what you want to pay for, not some imaginary VA value.

.

 

[mivey]

Can anyone tell me why we are charged for watts instead of volt-amps?

Because the POCO is selling energy and watts is a measure of how fast the energy is consumed.

With the proliferation of CFLs and all the discussion about the poor power factor it seems to me that the POCO is not getting paid for all of it's energy. Now, since they can charge what they want to stay in business, I foresee a rate hike to cover the VAR's not being charged for, yet used increasingly as time goes by.

The cost of vars are included in the other charges. They account for it on a system-wide basis even if they do not itemize it on the bill. That does not mean the costs are always ideally allocated to those who caused the cost.

The customer is going to pay no matter what. I think being charged for VA's would be beneficial to all. People are thinking they are saving a bunch of energy by using CFL's. They don't realize that there is more energy (pollution) needed to be generated than it would seem by only looking at watts. If we concentrated on reducing our VA's we would directly be reducing the energy being produced. Reducing our VAR's is also reducing energy being produced that does nothing in return.

Maybe I am missing out on something, but if I was the POCO I would charge for Volt Amp Hours, not Watt hours.

You would be charging for something that was not completely consumed.

 

[ControlFreak]

Another thing: Unloaded motors. I can't tell you how many hydraulic pumps we run all of the time . . . and it kills our PF(but not to the point of being charged extra). However, those motors aren't actually doing any work until they are moving pistons. I'm sure many factories in America(and the world) do the same.

 

[mivey]

I don't follow you.....

If you have a big enough load and a bad enough power factor, the POCO will charge more for the watts the meter reads. That is why factories utilize power factor correction. Why would they be able to do that if, as you say, it doesn't matter?

The cost to measure the vars for individual customers has historically been cost prohibitive and thus was limited to bigger customers. The smaller guys just pick up a portion through an allocation based on averages for the rate group.

Also, if watts and VA's are the same in the eyes of the generation point, why the rating of both watts and VA's on a portable generator?

They are not viewed as the same.

I still think that the fuel a generation facility uses is based upon the energy produced (Volt Amps) and the actual power being used (Watts).

The normal fuel burn is based on the energy lost (watts) since that is the energy consumed. The size is based on the VA needed.

If VAR's don't use up energy how can they even exist? I was taught that VAR's consume energy but don't provide working power.

Watt-hours delivered are watt-hours consumed. You must also include the watt-hours lost in the delivery process.

Var-hours delivered are not consumed but returned. But, you must also include the watt-hours lost in the delivery process.

 

[mivey]

Another thing: Unloaded motors. I can't tell you how many hydraulic pumps we run all of the time . . . and it kills our PF(but not to the point of being charged extra). However, those motors aren't actually doing any work until they are moving pistons. I'm sure many factories in America(and the world) do the same.

Sawmills are notorious offenders as they only load up when a log runs through the saw.

 

[mivey]

And this is kind of what I am not liking.

People that have good power factors are paying for those that don't.

In a lot of rates, yes.

Thus, there is only a motivation to reduce watts, even at the expense of power factor.

Correct

If we were charged for VA's, we would be motivated to reduce those, which would be a much more fair system, and more effective at attaining the goal of total energy efficiency.

But....that may be bad for CFL sales....

In a perfect world, you would charge for a poor power factor. The metering costs have not made this feasible for small customers in the past.

In a perfect world, you would also charge for demand but metering costs have historically restricted this activity.

 

[Fulthrotl]

Can anyone tell me why we are charged for watts instead of volt-amps?

Now, I'm not complaining, but I am the consumer, not the POCO.

With the proliferation of CFLs and all the discussion about the poor power factor it seems to me that the POCO is not getting paid for all of it's energy. Now, since they can charge what they want to stay in business, I foresee a rate hike to cover the VAR's not being charged for, yet used increasingly as time goes by.

The customer is going to pay no matter what. I think being charged for VA's would be beneficial to all. People are thinking they are saving a bunch of energy by using CFL's. They don't realize that there is more energy (pollution) needed to be generated than it would seem by only looking at watts. If we concentrated on reducing our VA's we would directly be reducing the energy being produced. Reducing our VAR's is also reducing energy being produced that does nothing in return.

Maybe I am missing out on something, but if I was the POCO I would charge for Volt Amp Hours, not Watt hours.

true power is expressed in watts.... around this area, anything over 400
amp service, has a demand meter socket, so they can see how dirty
your consumption is. if you have a lot of inductive loads, and they all
cycle on at once, your power factor goes in the toilet, and you ping
the demand meter, which stays at the worst setting until reset by the
meter reader at billing time, and it provides the multiplier for computing
the rate you pay for ALL of your electricity for the whole month.

the reason being that the POCO has to provide that service capacity
for you, and KVAR's aren't billable by a wattmeter, but reactive power,
while subtractive from the power consumed, still needs to be provided
by the POCO, to make your large inductive or capacitive loads function.

small residential loads aren't worth individual computation to the POCO.
they set your residential kwh rate at whatever they need to show a profit.
that usually is about the 90% p.f. rate they charge the commercial
customers, if memory serves...

 

[K8MHZ]

Suppose all loads were simply capacitors.

To say that a purely capacitive load is the same as no load at all makes no sense to me.

Now, if you threw in an inductor and made a tank circuit, I would concede that this would be very close to an open circuit as far as how much energy is needed from the generator.

In my feeble mind, a purely resistive, a purely capacitive and a purely inductive load all will require some torque on the shaft of the generator to supply.

A purely resonant or an open circuit will not.

(Losses inherent to physics, such as friction, not considered....)

 

[K8MHZ]

small residential loads aren't worth individual computation to the POCO.

That makes much more sense than saying VAR's don't cost the POCO anything.

Easier to believe, as well.

 

[mivey]

That makes much more sense than saying VAR's don't cost the POCO anything.

Not exactly what zog said.

 

[charlie b]

I was taught that VAR's consume energy but don't provide working power.

Not true, I am afraid. Mivey said it one way, at the bottom of post 11. I'll put it another way, using several examples. Reactive power is an exchange of energy between (1) The magnetic field of a utility generator, and (2) The magnetic field of a motor load. It can also be an exchange of energy between (1) The magnetic field of the secondary windings of a transformer, and (2) The magnetic field of a motor load. It can also be an exchange of energy between (1) The magnetic field of a utility generator, and (2) The electric field of a capacitor bank.

In all cases, it is an exchange of energy. Energy flows in, and then energy flows out. In the interim, it does not do any "useful work." But if it were not present, the motor would not have a magnetic field to drive its rotor in a circular motion. The fact that energy moves in and out causes the total current in the transmission line to be higher, and therefore there are additional loses. That is something the utility would prefer to minimize, which is why they sometimes give credits or penalties to large customers, based on the power factor of the facility.

 

[mivey]

To say that a purely capacitive load is the same as no load at all makes no sense to me.

Now, if you threw in an inductor and made a tank circuit, I would concede that this would be very close to an open circuit as far as how much energy is needed from the generator.

In my feeble mind, a purely resistive, a purely capacitive and a purely inductive load all will require some torque on the shaft of the generator to supply.

A purely resonant or an open circuit will not.

(Losses inherent to physics, such as friction, not considered....)

But losses are the key. Even a resonant circuit will have losses that must be replenished by the generator. The difference is that the inductor you threw in is the temporary storage tank instead of the source. They just go through a different process to store then release the energy.

 

[charlie b]

In my feeble mind, a purely resistive, a purely capacitive and a purely inductive load all will require some torque on the shaft of the generator to supply.

If there is any resistance, there will be losses due to heating, and the generator will have to continue to supply energy to make up for those losses. But if the load is purely capacitive or purely inductive, then the generator will have to provide an initial amount of energy, to start the "energy exchange" (that I mention earlier) going. Thereafter, ignoring friction, as you suggest, the generator and the (purely capacitive or purely inductive) load will exchange energy with no additional push needed from the generator's prime mover. The weakness in this statement, of course, is that the wires that connect the generator to the load will have some resistance. That brings us back to my first sentence in this post.