Thank you for that illuminating reply. I don't quite understand why you bother though. Surely any possible humour in your persistently childish responses has worn thin by now? Or is that really the best you can do? In which case you have my sympathy.
I sat open mouthed while watching the News at Ten tonight. With all the spin on renewables we've endured over recent years, they finally admitted what offshore wind costs - 85quid/MWh!!!
The figures they quoted were:
Coal 30ukp/MWh Gas 38ukp/MWh (and going up no doubt) Nuclear 39ukp/MWh Offshore Wind 85ukp/MWh
Some green energy companies will pay you based on what appears to be a calculation (ie gross overestimate) of what your turbine might produce. I note that Equipower will pay you 18p for every unit you export vrom your solar panel! All this to get their hands on ROCs!
T
You sure about that? I oversimplified.
For a poor PF load the voltage and current are out of phase with each other (how far depends on the PF PF=1 is in phase, PF=0 is 90deg out). The generator is producing (and consuming fuel for) VA (real power). However, domestic consumers pay by W (apparent power), not VA. So you see
30W of load at the meter and can measure the AC RMS current into the lamp, but the V and A waveforms are out of phase so the actual V*A is greater than the W value. (W=VA*PF so a 30W (apparent power) lamp with a PF of 0.5 will require 30/0.5=60VA input to power it)Agreed that the distribution losses into poor PF loads also escalate with I^2R.
Also agree that the % difference on your bill will be insignificant. :-)
It doesn't work like that. What's happening at the per mains cycle level is that at one point in the cycle you are drawing more power than you need, and at another point you are giving back the excess. The supply infrastructure has to carry and be sized for this extra power you took and then gave back (and weren't charged for) plus the power you actually used, but all that happens is that someone else will use the power you gave back and the generator doesn't need to produce it again for them.
However, the low power factor resulting from compact fluorescents doesn't involve any significant phase shift. It results because the power supply in the lamps only draws power in the peaks of the waveform. This power draw only in the peak is stored in the lamp and used to generate a continuous output. However, with supply losses being I^2R, drawing twice the current for half the time still generates twice the power loss in the supply infrastructure, although as Andy pointed out, that's still less than the losses from an equivalent filament lamp. But the power station in this case only has to generate the power for the period of the cycle when the lamp draws it. Inertia of the generator armatures smooths this out in practice.
Substations have BANKS..ACRES of capacitors to correct for power factor, so that the generators do NOT have to run widely differing VI phase differences. Its not really clear what sort of PF a CFL is anyway..A bridge rect and an electrolytic maybe? Or a half wave rect and an electrolytic..I bet there is a lot of input ripple..its easy enough to stabilise output ripple with an HF SMPS..anyway a bot of C across the mains is good, as its in the reverse direction to all those motors and things..there the current lags the voltage..with capacitors it tends to lead a bit.
well the last statement is a bit specious, given the miles of inductive line and the leakage inductance of all the transformers in between..
The generator is consuming fuel for W + losses, not VA. VA(R) produces additional losses in resistive components of the distribution due to circulating currents, but in itself consumes no extra power in the load on the generator.
Interesting. I missed that.
It feels about right from my own calcs. I'd put the offshore wind costs higher than that tho..a huge amount depends on how much the wind blows, in the windmill case, and how much the nuclear reactors are run flat out and therefore getting best use of capital,and fixed overheads, in the nuclear case.
Both have virtually zero fuel costs but high fixed costs.
Another unknown factor is how long the stuff will last. The magnox stuff has done what - 50 years? Will the windmills survive a hurricane or three? I'd laugh myself silly if we see a aerial view of a lot of poles standing in the water with the blades snapped off. Its all very well feathering them IF the wind direction is constant.But would they stand turbulence..at 120 mph? And what if the feathering or head rotation mechanism fails..
Anyway, cost per KW is a function of the lifetime..you could argue - and certainly British Energy shareholders seem to be, that teh vcapital cost has depreciated to nothing, and its all profit..over running and maintenance costs.
I don't know if you remember Clarkson on the supertanker 'This ship will be run until the cost of maintaining it exceeds the cost of borrowing enough to build another one: then it will be scrapped.'
I.e. if your maintenance costs of a nuclear power station exceed the cost of borrowing enough to build a new one and decommission the old, you do that. I suspect that the way British Energy will go now..get a new one built alongside, and use that to fund the decommissioning of the older sets. Then nick the turbines and boilers and generators and use them in another set..if they are worth using.
On 10 Jan 2008 20:07:50 GMT someone who may be snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) wrote this:-
Indeed.
That this is a myth has been explained many times before, but for those whose religion appears to be opposing anything green
On Thu, 10 Jan 2008 07:34:01 -0800 (PST) someone who may be "Man at B&Q" wrote this:-
You are assuming all heating is by convection.
On 10 Jan 2008 15:01:22 GMT someone who may be Huge wrote this:-
Excellent, rudeness and personal attacks in one posting. Do keep it up.
The figures in there are a little out of date, and not for the EU. We're better than that now with CFLs. Typical mercury contents of new CFLs is now down to 3mg. Another 2.5mg is given off in the electricty production, which is 5.5mg total. For an equivalent filament lamp, 10mg is given off in the electricity production.
IIRC, the EU max permitted mercury in a CFL is 5mg, but that would have been written some time ago, and advances have allowed less to be used since then.
The environment will suffer far more from the dumping of end of life CFLs and all they contain, than a bit of tungsten, glass and some inert gas.
MBQ
It's the power used when bulbs are switched on which is the cost to the environment.
Mary
Well you keep making statements without any back-up, is that the best you can do?
Mary
Oh, I didn't see that. People who write offensive posts end up in my kf so I miss such gems :-)
Mary
Just had a thought though, I don't mind being associated with David Hansen, nor being enthusiastic about important matters. Being positive is better than being negative.
Mary
How naive.
You could get three 5' complete flourescent fittings with electronic ballasts for that.
I don't think that's a fair point though. I mean has anyone been forced to use petrol perhaps then we should ban it ;-)
yes I have three in use but they aren't much good for lighting unless you're about a foot away from them. I use them in the hallway but presently they are just too dim to be practical anywhere else.
Me too but I don;t wnat to watch TV by blue green or red light even if it does cycle between the colours. :)
I'm not sure the problems are imagined.
OLEDs mighy be next.
I'm waiting for the time when each buld with have it's own sealed mini nuclear reactor in it and a guernetee where it's worth you're while taking the used bulb back to the supplier and you swop it out for a replacent for minmal cost.
If people got a couple of quid back for expended bulbs then that would do far more to encourage true recycling. I remember the days when you'd get money back on beer bottles. I imagined I could become a millionaire from returning my empties but they stopped all that. :-(
No buts about it.
}Why? Give us the science.
Because keeping the ceiling warm isn't a good idea unless you live above the ceiling. A lot of the heat generated in a bulb is in the filament and doesn't get passed on very far even though the glass gets quite hot, there's not usualy enough air circulation to take theheat from the bulb.
}Where do you think the air warmed by a heater ends up?
It doesn't really end up anywhere it gets dissipated and cools as it circulates.
} the heat from the heater? Think of the bulb as providing }the heat that would anyway dissipate through the ceiling to save the }heater from having to do it.
}Same applies to TVs on standby.
But wasteful and ineffective as using a soldering irn to heat your home yes it gets hot. Similar thing with a kettle.
My father uses bulbs to warm things up but limits it to hospital cages for budgies where the bulb is under the cage and the heat rises which is fine for a small cage and a bird but a human would hardly notice the room warming up due to a 100w incandescent bulb.
If it were such a good idea to have heat sources up high then radiators would be mounted up high on the wall where they could be run much hotter due to people being less likely to burn themselves if brushing against them.
It also seems to be why radiators are commonly placed under windows so they can heat up the cold air around the windows making it rise, after all there's little point in heating up hot air that is above your head.
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