chaos in power and energy

[Bhuvanesh123]

why the factories calculate for power? Why dont they come up with energy?

pwr=energy/t.it means change in energy in time
energy =power*time. what does it mean?

even if we on all vacuum cleaners,ac in city.Everythings working with no signs of abating

 

[WimRFP]

They calculate with both power and energy. When converting hydrocarbons to electrical energy, the required power (kW, MW, etc) determines how much kg fuel you burn per second, hence the daily supply of fuel.

To avoid interruptions one need to store a certain amount of energy (for example in the form of fuel) to overcome periods of fuel shortage or delivery problems.

In systems where a certain power has to be delivered during certain time, the power requirements determine the size of the installation and not the energy requirements. With size I mean size of generator, wiring, cooling system, supply lines, etc.

When energy storage is important (think of cars), the size of the storage installation depends on the amount of energy that has to be stored. The reason that we still use hydrocarbons in our cars is that the energy density is high compared to the energy density of batteries.

When we put on all our electrical appliances we have at the same time, the grid can't provide the power (or energy/s).

 

[Bhuvanesh123]

They calculate with both power and energy. When converting hydrocarbons to electrical energy, the required power (kW, MW, etc) determines how much kg fuel you burn per second, hence the daily supply of fuel.

To avoid interruptions one need to store a certain amount of energy (for example in the form of fuel) to overcome periods of fuel shortage or delivery problems.

In systems where a certain power has to be delivered during certain time, the power requirements determine the size of the installation and not the energy requirements. With size I mean size of generator, wiring, cooling system, supply lines, etc.

When energy storage is important (think of cars), the size of the storage installation depends on the amount of energy that has to be stored. The reason that we still use hydrocarbons in our cars is that the energy density is high compared to the energy density of batteries.

When we put on all our electrical appliances we have at the same time, the grid can't provide the power (or energy/s).

the size of installation ?

 

[Audioguru]

In my city in the south of Canada they designed electricity generating stations properly to be able to provide all the electricity consumed by industry and homes which had a maximum that occurred in the middle of summer for air conditioning. Other countries do not provide enough electricity so they cut off the power to areas at different times called "load sharing".
That changed recently in Canada when air conditioners were replaced with more efficient ones so the maximum electricity use occurs just before Christmas for Christmas tree and Christmas outdoors incandescent lighting.

To prevent an increasing demand for electricity the electrical utility company gave away low power compact fluorescent light bulbs and LED Christmas tree lights for free. The government also banned the manufacturing of high power incandescent light bulbs.

 

[WimRFP]

With "size of the installation" I mean the physical size of the electricity station where they generate the electric power (or electric energy).

Just an example
If you have a year to generate 1000 MJ (electrical energy), you may use a relatively small solar cell system, as the average power is 32W.

However when you need to generate the same 1000 MJ in an 8 hour working day, you need an installation that can produce almost 35 kW during 8 hours (rental generator with weight of about 1800 kg?).

 

[BradtheRad]

energy =power*time. what it mean

When we speak of power usage at a given moment, the units are watts/ kilowatts/ megawatts/ gigawatts.

When we wish to factor in time, then the units are watt-hours.

 

[Bhuvanesh123]

They calculate with both power and energy..

no sir i think they charge for only power.This is what they said georgia institute of tech in coursera site .
if they charge for energy(e=p*t).in no matter of time they consume lot of power

 

[Audioguru]

Homes in my city have "smart meters". The calculate lower electricity rates after 7:00PM each business day and all weekend. The charges are for kWhrs.

 

[betwixt]

I think the confusion here is between electricity generation and electricity consumption.

Electricity generating station need to know how much to generate at any time to cater for expected load and then an extra amount for safety margin. At locations away from the equatorial regions this can be very seasonal so the electricity companies need to predict likely loads. For example, Audioguru is about 43 degrees north, I am about 53 degrees north and Bhuvanesh123 is only about 24 degrees north, when all heating and air conditioning is taken into account, the further north and away from coasts you are, the greater the change in electricty over the year is likely to be, particularly if you rely on electricity for heating.

Consumption is how much of that power is being used in real time. Obviously the amount generated has to be higher than the amount consumed or you get a blackout. Consumption is the instantaneous amount you use multiplied by how long you use it for so time comes into the equation and the normal method of measurement is KWH (Kilo Watt Hours). It gives a good measurment of how much of the system capacity you are actually using and hence is used to calculate your electricity bill.

Like in Audioguru's location, here in the UK the sale of larger sized incandescent lamps is banned and CFLs are often given away or sold at subsidized prices by the electricity companies. Many homes also have "smart meters" to show live usage figures and in some cases there are grants towards the cost of micro-generation schemes. I have about 2.5KW PV capacity and 75KW solar water heating capacity, I would be rich if they could be powered by rain instead of sunshine! Much of my country is flooded at the moment!

Brian.

 

[WimRFP]

no sir i think they charge for only power.This is what they said georgia institute of tech in coursera site .
if they charge for energy(e=p*t).in no matter of time they consume lot of power

There may be some (language?) confusion overhere.

I limit myself to electrical energy now.

Your electricity bill may show various costs (depending on country and location):

costs for administration
costs for transport of electrical energy
costs for metering services
costs for construction work (for example if you need a thicker cable because of certain power demand)
costs for energy you used (for example during a month or year).
taxes

When you look to your electricity bill, the billing unit for energy used is very likely kWh. This is a product of power*time, hence energy.

1 kWh = 1kW*1h = 1000*3600s = 3.6 MWs = 3.6 MJ.

So thay charge you for Energy + "service" costs and not power.

Of course service costs may be higher for a high power connection to your house/facililty.

If you convert 1kWh into heat energy, you get about the same heat energy when burning 0.1 kg of kerosine.

 

[Audioguru]

There is a company phoning me wanting to put solar panels on the roof of my home. They pay me a little "rent" for the use of my roof and they sell electricity to the utility company for 20 years. After 20 years the solar panels are mine for free. They claim that they will last for another 20 years but do not say why they abandon them (obviously because they will fail?).

Meanwhile there is an apartment building in my city where the wind is blowing down solar panels on its roof and the entire neighbourhood is kept away.

Here, cheap natural gas is used for heating, not electricity. Some people use natural gas in their BBQs. Even some cars run on natural gas.

 

[betwixt]

PV panels are actually very reliable and lose around 1% of their output per year. After 20 years they should still produce around 80% of their rated output. In the UK we have a "feed in" value which the electricity company repay you if you generate back into the grid. Unfortunately here I'm on a small local supply that doesn't run that scheme and there is no gas supply in the area so anything I can generate for myself is a bonus. The cost per KWH here is also high (about $0.82 Canadian at todays exchange rate) so PV becomes economical to fit even with low usage.

Brian.

 

[WimRFP]

OT:
@betwixt: is it really 0.82 Can. $ (so about 0.54 Euro)? Here we pay about 0.23 Euro/kWh (tax and VAT included).

@Audioguru: We have also rental/investment schemes for pV electricity, but there are some legal limitations.

 

[betwixt]

Yes, I pay 0.45 UK which is about 0.54 Euro and also a daily charge of 0.54 Euro as well. It is less from some companies but I can not change supplier.

Brian.

 

[avrilcory]

Chaos Powers are abilities to manipulate Chaos Energy in various ways. In the first, additional wind power came from within the solar companies. In the second, some additional wind power is tapped some imported from the windier. These policies have impeded the development of cheap and abundant domestic energy sources. They have also resulted in very inefficient fuel-mix choices compromising energy and economic security.


Thanks
Luminousrenewable

 

[123jack]

...
Like in Audioguru's location, here in the UK the sale of larger sized incandescent lamps is banned and CFLs are often given away or sold at subsidized prices by the electricity companies.
...
Brian.

I seem to recall that incandescent bulbs are not banned in the UK. The government persuaded the large supermarkets not to stock them. Fortunately you can still obtain them in smaller retail outlets.
The newer so called energy efficient lamps are a disaster for the environment - resulted in a reduced
electrical noise regulation because they couldn't make then meet existing standards, dont last anywhere near as long as claimed and dont give off light in any manner safe for your eyes at the levels they claim on the box.
To get a decent 100 watt incandescent equivalent you need to install 2 bulbs and consume more electricity not less. The whole thing is a political and financial scam as far as I can see.
We have found here that even the halogen versions only last 3-4 months - not the 2 years claimed on the boxes.
I rather suspect the ongoing fall in UK electrical consumption over the last 10 years has been caused
by the lower consumption of computing devices and especially TV/display screens. Light bulbs I'd suggest contribute next to nothing to this. ....

To answer the original question - because its operationally convenient.

 

[betwixt]

Perhaps I was misleading, the sale is not banned to the end user but none are fed into the supply chain, as stocks diminish they will not be replaced.

I agree CFLs are bad news, no only because of poor performance/longevity but for their chemical poluting during manufacture and disposal. On the bright side (sorry about the pun) in many cases they can be repaired when they fail. In my opinion, halogen is even worse because of their higher temperature and shorter life. Next door to me is a block of luxury holiday apartments which were built in 2005/2006, their owner wanted to be a 'green' as possible and followed the advice given by a lighting company to only use halogen lamps. I spend lots of time replacing them, often several every week and twice there have been electrical problems because wiring to the holders has got so hot it charred the incoming cables and caused shorts.

Personally, I would go for LED lighting and (hopefully) I'm going to demolish my house and rebuild it later this year with low voltage wiring for the lights. I don't intend to use conventional 230V SMPS in every light fitting due to the reliability and potential to cause radio interference (lots of sensitive receivers here). Instead, I plan to use a DC feed, probably at 12V to all the light fittings and fit a micro controlled PWM dimming circuit in the luminaire if necessary. Using LV also makes me far less prone to the effects of power outages which are common here because I can switch straight over to a battery. I've already installed an experimental 230V LED light in one room using a conventional transformer/bridge/cap/resistor PSU and 6 warm-white LEDs it works as well as a CFL, is dimmable and should last longer than me.

Brian.