Gore: U.S. Can Get 100 Percent Renewable Energy in 10 Years ?

[Besoeker]

Originally Posted by LMagic007

Energy cannot be created or destroyed and does not require time passage to exist at any moment.

Might I suggest that you check the definition of the joule?

[LMagic007]

Originally Posted by Besoeker

Might I suggest that you check the definition of the joule?

No need. Energy cannot be created or destroyed. It's always present at all moments in time.

[Besoeker]

Originally Posted by LMagic007

No need.

Well, it would increase your knowledge on the matter if you did, but, if you don't care to check the definition of the fundamental unit of energy, that's fine. There's nothing more to be said.

[LMagic007]

Originally Posted by Besoeker

Well, it would increase your knowledge on the matter if you did, but, if you don't care to check the definition of the fundamental unit of energy, that's fine. There's nothing more to be said.

Have already seen it before. It does not change the notion that energy cannot be created or destroyed. Energy is always present at all moments in time.

[brianidaho]

Originally Posted by Deathridesahorse

Terrawatt-hours are energy units....Terrwatts are power units: apples and oranges!

Power is an Energy rate i.e. Energy / time!!

It's a simple concept with a fancy name called "Dimensional Analysis"

Watts are actually Joules per second. Scientists sometimes get attributed a unit name instead of a planet and is just a cultural thing.

Joules per second is an Energy rate as Joules is the proper unit for Energy.

Multiplying Watts by the number or hours you have used the elctricty in a month is how you get Watt-hours...Dimensionally Watt-hours= Joules!

There you have it...a simple as mud explanation!

(Yes, I failed Mechanical Engineering btw: l(no, seriously)ol!)

Actually, I think you have an error in your description...

A joule is a unit of work (force x distance), and is equal to 1 NewtonMeter (a force of 1 Newton applied for a distance of 1 meter)
A watt is a unit of power (work/time) and is 1 J/S (or one VoltAmp)
Energy is Power X Time (watt seconds or KwHours)

The odd thing being that if power=work/time and energy=powerXtime, energy=work. The "classic" definition IIRC says that energy is the potential for doing work.

So when all is said and done the unit of Energy is as you said a Joule as well.

At least that's my recollection.

And yes, if time=0, energy (by definition)=0.

(I didn't fail mechanical engineering but it's been too dang long since covering the basics in physics 1 or 2...if I'm wrong please correct me)

[LMagic007]

Energy cannot be created or destroyed. Energy is always present at all moments in time.

[LMagic007]

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[brianidaho]

Originally Posted by LMagic007

Energy cannot be created or destroyed. Energy is always present at all moments in time.

Technically you are correct, it that energy is not destroyed, it is converted to another form. The odd aspect comes from terminology to an extent. Electrical energy, when referred to as kWH, is more appropriately considered power consumption. Electrical energy is converted to another form, heat, mechanical work, etc. So with a time of zero, the "potential for doing work" exists due to the energy balance of whatever system, but "power consumption" equals zero. Just mudding up the waters even more.... The definition of work and power click for me reasonably well (as a mechanical guy)...actually understanding energy is really a bit more involved, and still confuses me to a point.

[Besoeker]

Originally Posted by brianidaho

Electrical energy, when referred to as kWH, is more appropriately considered power consumption.

Well, not really.
We have an electric kettle. I use it in the morning to boil about a litre of water to make tea - we Brits like tea, hot, not iced .
The power the kettle takes is 3kW. The energy it consumes is about 0.1 kWh.

[brianidaho]

Originally Posted by Besoeker

Well, not really.
We have an electric kettle. I use it in the morning to boil about a litre of water to make tea - we Brits like tea, hot, not iced .
The power the kettle takes is 3kW. The energy it consumes is about 0.1 kWh.

I beg to differ sort of. The amount of heat it takes to heat a fixed mass of liquid a certain amount is a unit of energy-BTU, Calories or kWh, etc. When you are speaking of 3kW, you are using talking about the rate of heat transfer (or power), in terms of Watts (J/S), Calories/Sec, BTU/sec, etc. The power it consumed (energy) to do so is a function of how long your electric kettle was on and drawing 3kW ( 2 minutes in your example).

To take it a step further, when you shut the kettle off, the energy used (.1 kWh) still exists in the system, now as thermal energy in the tea. But the power consumption (once you shut the power off) is now zero.

(lets not go into the latent heat stuff...this is getting deep already )