incandescent lights not *that* bad?

[Huge]

And dimmers.

Every light in my house is on either a dimmer or a timer.

[Andrew Gabriel]

There are compact fluorescents which are dimmable with ordinary dimmers. For some unknown reason, they aren't imported into the UK.

Dimming incandescent lamps makes them far less efficient then even the poor efficiency of running them at full power gives you.

[John Rumm]

Although might be worth pointing out that while the efficiency falls, so does the power consumption - just not as fast.

[Hamie]

Tungsten. Thorium is a radioactive metal. Not used in bulb filaments AFAIK. Google for halogen lamp. You'll get quite a few hits from manufacturers.

Yeah. I remember at school when one got smashed we all had to leave & they had to get someone in to clean it up...

H

[Ian Stirling]

Cos they'd explode. Nobodies (as yet) made a cheap dimmable light chipset. (well, chip)

[OG]

Nope, a while back I calculated that each fluorescent saved about £50 over its lifespan - and that was when they were £10 a pop.

[meow2222]

Filaments are not pure tungsten, thats the problem. Its to do with workability.

NT

[The Natural Philosopher]

Around about 55-65% With newest kit, from heat to electrons as it were.

From (rusty) memory

Steam piston engine 5-7% Petrol engine 15-35% Diesel 20-40% Gas turbine 30-50% Steam turbine with the full condenser kit 40-65%

The maximum energy available is a function of the maxim working fluid temperature and exhaust temperature. Condensing turbines use superheated steam and go down to wet dripping water and water vapour.

Gas turbines use very hot working fluid (air) and are good there, but exhausts temperatures are pretty high.

CHP that uses a gas turbine and the waste heat to heat water, and possibly even drive a steam turbine, is really rather good.

[nightjar]

They are a form of incandescent lamp and are not classed as hazardous waste.

Colin Bignell

[Pete C]

Hi,

Came across this the other day which gives the grid efficiency as a whole to be 30%:

[Hamie]

Granted.. But I don't think the additives are thorium...

[silicono2]

OK so the only hazard are the halogens in the bulb. But I remember they're really reactive and when exposed will form not-so-harmful compounds right away. A few of which we eat regularly too...

Seb

[Andy Champ]

I found this, when I didn't beleive OG's figures. Seems he does know what he's talking about.

[Fred]

I've read the article and recall in the 80's the maximum efficiency from a power station was 42%. Nevertheless the average was brought down by other power stations which included coal fuelled stations. Ironically the older and less efficient stations produced the cheapest electricity from a financial point of view because the capital value was already written off. I thought these older stations were around 30% efficiency. However the loss of transmission was considerable to bring the overall efficiency down to

25%. I am talking of the 80's.

More recently many old coal fuelled stations have either been scrapped or converted to oil. Also the combined-cycle generation is far more efficient. However few articles include transmission efficiency which perhaps is a more embarrassing issue. I see no reason to doubt the efficiency of the article in the Pete C's post of 36%.

[Stefek Zaba]

Kinda sorta plausible - a bit low, but lots of heat did go up the chimbleys, and more in the cooling towers.

Firstly, if your figures mean "losses in transmission reduce efficiency from

30% at generation plant to 25% at consumption point", those aren't 'considerable' losses - one part in 6, or 17%. But even that seems implausibly high to me: sources of loss would be conductor losses, transformer losses, and finally 'leaks' (little bits of corana discharge). All these losses end up as waste heat somewhere. Given the *huge* energies involved, the latter two really can't be that big, or you'd see transformers boiling and crops under overhead lines frazzling rather more often than you do! The only place you could dump enough heat not to notice is in conductor losses, as there's enough length of overhead and final-underground conductors to get slightly warmer than ambient without spectacular effect. However, precisely to limit resistive losses, main transmission lines run at very high voltages - 133kV, 400kV and friends - so I find the suggestion of 'considerable' losses implausible.

So do Googles sources: one clear one, written by a 'respectable-but-biased-against-electric-generation' source, is over at

claims "The transmission efficiency of electricity is 92.6%". That's a more plausible-to-me transmission efficiency.

And it's in line with the 'A'-level project writeup which Pete C quotes: which, if you read it, says quite clearly "... 26 TWh energy loss in transmission and distribution during 1998 due to unwanted heating effects in cables and substation equipment, out of a total of 350 TWh generated. This represents a loss of 7.4%." Sure, 7.4% of a-hell-of-a-lot is quite-a-lot, but as a proportion, three-fortieths isn't what many of us would dignify with the adjective 'considerable'.

Next you'll be like the fool on the radio this morning, uncritically repeating babblings about wind turbines being 'kept running' by a backfeed when the wind's not blowing, and claiming that this uses three times as much energy in a year as the turbine produces when the wind is blowing... what a pile of gonads!

Stefek

[Grimly Curmudgeon]

We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember Stefek Zaba saying something like:

Eh? FFS, I know journalists aren't all that technically aware, as a rule, but that takes the biscuit. What the f*ck does he think it is; some sort of giant table fan?

Hmmm... there's an idea; something for the glider pilots on a calm day.

[Matt]

The "kept running" is a load of crap but most wind generators have a large (and some would say disproportionate) reactive power requirements due to their use of induction generators. They can also cause instability and additional operational problems at precisely the time when they are required to perform.

[The Natural Philosopher]

Correction. It gives the grid efficiency as 92.5%. Its the power stations that are inefficient.

How much that matters in the case of e.g. nuclear power, is a moot point.

[The Natural Philosopher]

I agree. More than a certain percentage of windpower is not a practical thing.

We need power stations that can run on STORED energy - like water behund a dam, or a lump of uranium.

Windpower is too fickle - do you want to drive a land yacht to work?

[John]

What are the current stats on the pumped storage setup at Dinorwig in terms of operatinig efficiency and additional cost per kWh? anyone out there have the details to hand.