How green are low energy bulbs?
The EU has ruled that ordinary 40W / 60W / 100W incandescent lamps will be banned from 2012. The decree is that domestic lights will be replaced with ‘energy saving’ lightbulbs (or, more correctly ‘compact fluorescent lamps’ or CFLs) in the interest of energy saving and reducing our carbon footprint. It is claimed that these CFLs use 25% of the energy and last eight times as long as the equivalent incandescent lamps – and so will help “save the planet”.
To understand more, some key things to know about are apparent power, real power and the power factor. Apparent power is the amount of energy an electricity company needs to supply to produce the real power required by a component or a piece of equipment. Electrical equipment where the apparent power is the same as the real power has a power factor of 1. If a piece of equipment requires more apparent power to produce the real power, it has a power factor of less than 1. It doesn’t take a genius to work out that equipment with a power factor nearer 0 is not as ‘green’ or ‘environmentally sensitive’ as an electrical component with a power factor nearer 1.
Knowing this, I’ve tested several CFLs with surprising results: taking a sample 60W light bulb as a reference against the equivalent 13W CFL, the CFL used more than twice as much apparent power as real power. Compared with ordinary incandescent light bulbs, CFLs have a poor power factor because they require more than the minimum apparent power to supply the real power.
To understand more, some key things to know about are apparent power, real power and the power factor. Apparent power is the amount of energy an electricity company needs to supply to produce the real power required by a component or a piece of equipment. Electrical equipment where the apparent power is the same as the real power has a power factor of 1. If a piece of equipment requires more apparent power to produce the real power, it has a power factor of less than 1. It doesn’t take a genius to work out that equipment with a power factor nearer 0 is not as ‘green’ or ‘environmentally sensitive’ as an electrical component with a power factor nearer 1.
Knowing this, I’ve tested several CFLs with surprising results: taking a sample 60W light bulb as a reference against the equivalent 13W CFL, the CFL used more than twice as much apparent power as real power. Compared with ordinary incandescent light bulbs, CFLs have a poor power factor because they require more than the minimum apparent power to supply the real power.
My tests have shown that the CFLs use half the power of a 60W lamp, not quarter as stated and that’s before taking into account the extra power the supplier must generate.
The power difference between the real power consumed by the CFL (in the case of the Osram, it’s almost 15 watts) and the apparent power is wasted in more ways than one. The electricity supply becomes less efficient because it senses the difference between the real and apparent and becomes unbalanced by the redundant currents swilling around. The result is that it must generate more power than is really being used and the system needs to be upgraded to handle it. The cost of generation goes up and so the cost to the consumer goes up with it. The net result of using CFLs is that there is no saving whatever… quite the opposite; the electricity supply system has doubled its output and doubled its carbon emissions. The more people use CFLs, the worse the problem will become. And that’s before we’ve even talked about the fact that CFLs use mercury in their construction, which leads to more issues in their disposal. Utter stupidity… isn’t it better just to switch off a few lights?
What has all this got to do with your system? Hi-Fi and Home Cinema systems contain transformers and often have a low power factor. A 100W amplifier can demand up to 100 amps from the electricity supply for a millisecond to reproduce a drum transient. The lower the power factor, the less current is available to accurately reproduce the dynamics of your music – it’s effectively being used as ‘apparent’ power. And the more CFLs you fit, the worse the situation becomes. Me? I’m going back to candles!
posted by Russ Andrews @ 11:51 AM
17 comments
17 Comments:
My physics is 45 years rusty, but I would simply ask whether what is observed when measuring the behaviour of a single light bulb is important when assessing the work to be done by (or power load on) a power station supplying thousands of lights?
Will not smoothing or averaging give a different picture at the power station?
It is the power station coal, oil or gas consumption (and hence CO2 output) that matters at the end of the day.
I accept there is a puzzle here. Were you measuring just steady state usage excluding the higher load at switch on?
Also important to the individual user is what his meter records.
Did you do these measurements using something like the little devices that purport to tell us what we will be billed for each device in use?
Low energy bulbs also put out noise. Presumbly the transformers. Some are worse than others. To test, turn on a radio to LW radio 4 and move the radio close to a low energy bulb and hear it for your self.
Have you read the article by Paul Messenger on low energy bulbs in Hi-Fi Choice a few months back? He is stocking up on candescents!
Thanks for bringing this to our attention Russ. Candles might be the best option, but look out for the curtains! I've been doing a lot of stuff on LED lighting over the past couple of years for work, and the highest output Luxeon star LEDs appear to give excellent lux outputs relative to power usage, albeit withoutaccess to the facilities to measure power factors that you have. Maybe we'll find LED light clusters appearing more often as an alternative to both CFL's and normal tungsten bulbs in the near future. I think Screwfix are doing a small range these days. I have small task light strips of 4 piranha LEDS on my hi-fi which provide all the light needed to change CD or record.
The following is an excerpt from http://www.equitech.com/articles/enigma.html describing some of the problems inefficient fluorescent lighting has given in the past "For example, as much as 20% (or more) of the power used by fluorescent ballasts is reflected back onto the power grid in the form of reactive or harmonic currents -- now that’s a lot of distortion. In the late 80’s, a 40-plus-story office building in Los Angeles actually burst into flames because of these reactive currents. Incredibly, the origin of the fire was determined to be from excessive harmonic distortion in fluorescent lighting circuits which created a high-frequency current overload and literally a meltdown of the electrical wiring system. The First Interstate Bank fire in Los Angeles in May of 1988 was the event dubbed by the media as "The Towering Inferno" a la the Hollywood movie. Codes were adapted to remedy the fire danger, but the noise problem itself was never completely resolved."
One of my points was that when we are all forced to use CFLs, it really will be a big problem for the Power Generators.
They will have too generate far more power than is actually used and increase the current capacity of the system because there will be no way that the extra inductive load will balance out with enough capacitive load.
That means much more CO2, if that is what you are worried about. I'm more concerned with the costs, inefficiencies and scare mongering.
I'm a bit confused with the sums here. If the CFL's use half the power of incandescent does this not mean that the power station would only have to supply half the power even though the power factor is far lower? ie approximately half the CO2?
If the CFLs are less efficient than tungsten filaments then why do they NOT get as hot as filament Bulbs?
Mind you it is great that we discuss these things and not blindly accept all of the stuff put out. For example, how many of you believe that 1 gallon of bio-fuel produces less CO2 than petrol or diesel? All those who do put on the dunces hat and go to the back of the class.
Bill Mac, a confirmed LP fan.
Hello Russ,
I found explanation of terms "real power", "reactive power", "complex power" and "apparent power" (a modulus of complex power) at the following Internet link: http://tinyurl.com/2gz9ca.
So, it would seem that electric power is expressed as a complex number (in mathematical terms) and that "reactive power" is an imaginary part (a mathematical term) of that number. What I do not understand is if "reactive power" is a real power, i.e., if a generator has to produce a real energy (in Watts) to supply "reactive power"?
The link also says: "The ratio between real power and apparent power in a circuit is called the power factor."
Even if "reactive power" is a real power, I think, that your figures show that (although power factor for CFLs is less than 1 and for incandescent lamps practically 1), say, Osram 15W CFL (15W is "real power") consumes 27.66VA (which is its "apparent power"), which is less than 63.10VA ("reactive power" is practically zero) of 60W incandescent lamp (here I assumed that 60W incandescent lamp produces approximately as much of light power as Osram 15W CFL). So, according to this (even if "reactive power" is a real power) Osram 15W CFL would consume approximately 43.8% of power of 60W incandescent lamp and yet (according to the above assumption that 60W incandescent lamp produces approximately as much of light power as Osram 15W CFL) generate the same light power.
May I ask, if "reactive power" is not a real power, what would be a problem (the mentioned links says: "In power transmission and distribution, significant effort is made to control the reactive power flow.") if a circuit would have a power factor close to zero? Thanks.
May I also ask what is a power factor in average hi-fi integrated amplifier transformers (I am particularly interested in Cyrus integrated amplifies, models 7 and 8, with toroidal transformers) and what is its effect on sound quality? Thanks.
Regards,
Robert
Have to say I have never been convinced by the LE bulbs from the beginning. One thing I did notice in your magazine article which I would like to correct or at least develop. As an epilepsy sufferer it does become tiresome hearing all epipleptics being grouped together as being effected by flashing lights etc. Its bad enough going to the theatre or a rock concert. The fact is only a tiny % of epileptics have there seizures brought on by flashing lights, its one of those big mis understood points that everyone assumes.
Well, I happen to know for a fact that burning one gallon of ethanol releases less carbon dioxide than burning one gallon of petrol.
However, you need to burn more ethanol than petrol to get the same amount of energy.
If you look at carbon dioxide output for energy in an internal combustion engine ethanol can be slightly, but probably not significantly more efficient... but far more importantly, extracting oil uses a lot of energy which has most likely been produced by greenhouse gas emitting means. Conversely, when growing the bio-mass for bio-fuels the plants absorb some CO2 from the atmosphere. Also, the processes for making bio-fuel tend to be much less energy intensive than producing petrol from crude.
However, the carbon output of all the vehicles used in the growing of this bio-mass, as well as the impact of growing suitable plants on a given patch of earth rather than whatever was there before, would need to be taken into account. Bio-fuel has plenty of other problems too, e.g. the huge amounts of land that would be needed to produce it in quantities that would make it a viable alternative to petrol for a significant number of people.
So arguably, yes. Using bio-fuel is more environmentally friendly than using petrol or diesel. However, it is unlikely to be used widely (except as a fuel additive, which bio-ethanol already is) unless it becomes economically viable, i.e. cheaper than petrol to produce, which may well happen the way oil prices are going!
On a more Hi-Fi related note, another culprit where putting out interference and using a lot more power than they should is concerned is cheap, so called supermarket special electronics, especially the £20 variety of set top boxes and DVD players. I'm sure most people who are looking at Russ's blog wont be guilty of owning such things. But maybe we could use that as a way to introduce our environmentally conscious friends to to decent hi-fi and AV kit!!!
CFLs also cause artworks such as watercolours to fade in a way that incandescents do not. The average consumer is not aware that they have all the impact of standard fluorescent lighting.
I'd like to pick up on the last point because of an observation we made at work with optical brighteners. These made an article look whiter in daylight than the standard material but not under normal incandescent or fluorescent tubes.
We tried some CFLs and found that the cheaper ones (not philips) had the same effect as daylight i.e. a UV component (cause of fading) was still present in the light output.
I guess its a tiny fraction of that emitted by sunlight, especially in a Kiwi Summer, sorry!
The alarming revelation I made earlier about CFLs (the so-called ‘low-energy’ light bulbs) have had some interesting repercussions.
Lots of you sent me emails and letters, but newspapers have said “that can’t be right – we’ll check with the experts” and published nothing. At least one political party representative said the same – checked and came up with false information – and then went silent.
The silence is very interesting – and worrying. Is the ‘save the planet’ bandwagon so big and strong that no one dare question any of it? I checked my facts carefully before we printed them, but no one in any kind of authority seems to want to believe them. Where is Ben Goldacre when you need him? This bit of EU/UK pseudo-science should be right up his street.
Another claim made by the CFL manufacturers is about the light equivalence to incandescent lamps (you know how they put it – a 15W bulb is equivalent to a 75W incandescent). The results are rather mixed. I tested all 14 bulbs (including a candle!) with a lux meter and the test set-up on a turntable to get the average output from the end of the CFL. Unlike incandescent lamps, the light output from CFLs is not uniform all the way round, so I averaged the measurements of maximum and minimum on each CFL.
Several makes were represented; some were brand new, and some were old and used.
I found that there was some discrepancy between manufacturers’ claims of equivalence. GE and Lyvia claim that their 11W bulbs equal 60W of incandescent lamps, while Philips claim their 13W equals 60W. They were all wrong. The nearest to the light of a 60W incandescent was Lyvia’s 15W (and that was 15 lux dimmer than one). Lyvia claim their 15W equals a 75W incandescent. Their light outputs by my measurements are about 30% lower than their claims. Some makers give more light output than others of the same wattage.
Old examples perform worse than new ones, suggesting that the light output falls substantially over time.
So where does this leave us when comparing CFLs with incandescent lamps? The nearest equivalent to a 100W is probably a 26W CFL, costing you 52 watts, but only giving the full light output for about half of its life. They all claim 8000 hours life but everyone I have talked to who is using them is convinced they last much less than that. At £3 to £5 a pop, you need to save a lot of energy to make them pay. You are only saving 50% of the energy – not the 25% they claim – and getting about half of the life.
What is the point?
Sorry, the last line of my previous post should read:
"You are only saving 50% of the energy – not the 85% they claim – and getting about half of the life."
Sorry for any confusion.
This may be an over simplification but, if we say a 15W CFL produces the same light as a 75W incandescent, where the power station has to produce 75VA. The CFL saves the power station 43VA (based on CFL power factor of 0.47) which is 42%. If I am correct, then surely the power station needs to generate less?
Hello,
I use these "energy efficient" bulbs.
My reasons were financial, though I don't have any figures I do remember claims being made about cost savings per year when using these bulbs.
Can anyone remember any such claims, and what can the average family household expect to save by changing all the 60w standard light bulbs to Osrams offerings (though I also found the ratings not to live up to claims and use Osram 100w equivalents).
Basically, am I at least halving the cost of my lighting bill by using energy efficient bulbs or not?
Personally, no one I know has changed to energy efficient bulbs to save the planet, but to try and save money, yet no one seems to have any evidence of actual money saved?
Electric and gas companies have been ripping us off and using "dodgy methods" to get more money out of us for years. Many cannot afford to save the planet as they are too busy trying to keep up with inflation and price hikes each year.
Steve
Hi
My Engineering is a bit rusty too, but the 'Real Power' is the heating effect. That is, the equivalent Direct Current. It is the Root Mean Square or RMS of the alternating current and voltage.
The electricity company gives us A/C Alternating current. It is 3-phase A/C in the power station and in the distribution up to the sub-stations. If the phases get out of balance then there is much more power wasted as heat.
In the domesic setting, a good-old incandescent bulb generates light, but as it isn't very efficient, plenty of heat too.
This is only waste heat if your central heating system isn't on because it's warm weather, or if the bulb is outside. Your house needs heating anyway, and if the lightbulb raises the temperature slightly in the house, the thermostat will kick in that much earlier.
Other than that, CFT's are not efficient unless they are left on all the time.
Switching on gives poor light output and a power spike and a power factor blip.
The bulb is heavier. As you can see, they are made in the PRC (China), so the airmiles are high and the carbon footprint of manufacture is higher.
Added to hat, the incandescent is simple sheet metal, a tiny bit of resin, wire and glass. 100% recyclable into new product. (if we could be bothered collecting them).
Whereas the CFT has a fluorescent coating on the glass making it non-trivial to re-use, poisonous heavy metal (mercury), thermoplastic case, electronic circuity. In other words, it is hazardous waste!
The only advantage and saving grace, is that they do last a long time.
But they ain't 'Green'!
Dave
For the general consumer, the saving is still there compared to an incandescent lights, because typically energy meters installed in households do not count the reactive power. Companies however have meters installed which count the reactive power, and there are penalties for having a poor power factor. One way or another, the utilities have to pay for the reactive power, and they are sure to transfer the costs. I know the newer CFLs have some reactive power compensation. Does anybody know if there are any rules regulating the minimum allowable power factor for CFLs?
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