Energy Returned on Energy Invested Thread pt 2 (EROEI) (merg

[pstarr]

You are using lingo incorrectly.

EROEI (Energy Returned on Energy Input) is an acronym specifically coined to measure and value primary energy sources, such as petroleum, nuclear, or solar energy. EROEI is tool (a type of life-cycle analysis) that determines the relationship between the energy used to extract or produce a constrained energy-containing material, and the energy content of that material.

EROEI is not a measure of energy loss to heat or entropy, as I believe you are looking for. I think you are looking for measures of efficiency

[captain_ignorant]

I think what IslandCrow was looking for was how much energy actually goes into manufacturing the LEDs compared to other forms of illumination.
Incandescent bulbs are easy to manufacture (glass and wire) yet not very efficient. They are easy to recycle.
Compact Fluoro require electronics and take more energy to manufacture than incandescent as well as hazardous materials to dispose. They are more efficient.
LEDs involve Gallium Aluminium Arsenide (from memory) and I wonder how much energy is used and pollution created in manufacture. They are far more efficient on light per watt than any other form. Any ideas?

[Bas]

LED bulbs should be very cheap to make, cheaper than incandescent bulbs even; the high price for them now is probably due to the high research costs and initial capital spending. I see them come down in price dramatically in the near future, though I'm not exactly sure when.

[IslandCrow]

What I meant was 'How much energy goes into making the things?'

The bulb I am looking to get totals 3 watts and would replace a 60 watt bulb. Making a great savings (95%) in energy used for that application. But the manufacturing process seems to be quite high-tech and presumably energy intensive.

I want to pat myself on the back for being a good citizen and reducing energy consumption :-, but 95% savings just sound too good to be true, and "If something sounds too good to be true, then it is too good to be true".

[Bas]

As far as I know it takes much less energy in making a LED bulb than any other existing kind of bulb.

[jlpicard2]

The bulb I am looking to get totals 3 watts and would replace a 60 watt bulb. Making a great savings (95%) in energy used for that application.

Note the brightness of LED bulbs. Most use few Watts, and are likewise very dim. They can have their places in the home, but you may be disappointed how little light they emit compare to compact florescent lights.

[Kris]

I don't know about LED's for space illumination, but I do have LED lights for my bikes. A four LED taillight from MEC cost me all of $3CDN. They can't be that expensive to make. The thing is VERY bright, hurts the eyes to look at it when it's pitch black out and has run for likely 50 hours on the 2 cheap AAA batteries it came with.

[gg3]

LEDs almost certainly require less energy & ecological externalities to produce & use than other forms of lighting. Look very closely at an LED. What you see is a tiny little dot of material in between two contacts, encased in a hemispheric plastic dome. The tiny dot of material is what emits the light, and it's the point at which the nasty chemicals are used. A very tiny bit of nasty chemicals, that are forever entrapped under the plastic, and from which the light output is good for 100,000 hours.

True that present LED lights are not particularly bright compared to CFs.

However!

I recently got a Freeplay Indigo windup lantern. At the top is a cluster of white LEDs with a reflector system to spread the light around the room, and this is controlled by a dimmer. There is also a single very large LED at the front that is controlled by an on/off switch and that is normally used for task lighting.

The light this thing puts out, while hardly as bright as even a single CF, is sufficient to enable me to do just about any normal task, and I have been testing it for all of my normal lighting applications.

At this very moment I've parked it in front of my keyboard between my hands as they rest on the keys, and the light on even a very low setting is more than enough to type with, it's perfectly satisfactory.

At night I've been using the task light to read in bed before going to sleep. That task light is shockingly bright; at a distance of about 3 feet from the page, it is effectively brighter than the compact fluorescent that is only another foot or two away. All of the light is focused on the printed page rather than lighting the whole room. For those of you who have a partner, you could stay up reading while they sleep, and they wouldn't be bothered by the light.

So what I think you'll find is, if you use LED lighting correctly, it can replace normal compact fluorescents in a surprising number of applications.

In many parts of a house you only need a light level sufficient to find your way around safely, which, after you get used to lower lighting all'round, is not much more than a night light.

For specific tasks, use task lighting.

There is only one thing I would improve about the Freeplay lantern, and that would be to provide a clip-on reflector to focus all of the light in one direction. As it is I've done that temporarily with a piece of aluminium foil, and shortly will be making some kind of semi-permanent attachment for this purpose, probably from polished aluminum.

The other thing I would improve about LED lighting generally, is to have a mix of white, red, green, blue, and yellow LEDs, and a separate dimmer screw for each color. This way you could adjust the color balance to suit your preferences, and get a "warmer" overall color of light.

Last but not least, when the Freeplay lantern's internal battery is fully charged, it lasts for so long that I haven't managed to drain it yet, in days of intermittent testing. Very very very efficient.

The AC charger, by the way, uses 0.01 amps at 120 volts, which is a total 1.2 watts while the light is turned on or the battery is charging, and zero (0.00 amps) when the charger is idle. (Normally you'd use the charger to keep it on charge, and then use the hand crank to charge it up during a lengthy blackout.) I'm probably going to buy another one of these shortly ($40), so I've always got one fully charged while the other is in use.

If you're on solar or household wind power, LEDs are definitely the way to go. Putting these things in every room, plugged into the wall, they will more than pay for themselves compared to adding PV capacity. And you can still have a couple of CFs around for times when you need to light up an entire room brightly, for example when you're cooking a meal or taking a shower.

Bottom line: If you're even the least bit curious, go ahead and buy one or two of those $20 LED lightbulbs just as an experiment and then try them in various places in the house to see how you like them and where they can be used that works for you. Or buy the Freeplay Indigo and you can carry it around the house like a 21st century candle.

[IslandCrow]

Bottom line: If you're even the least bit curious, go ahead and buy one or two of those $20 LED lightbulbs just as an experiment and then try them in various places in the house to see how you like them and where they can be used that works for you.

I will (next time I go to town), even if the price is a rip-off.

[tsakach]

What I meant was 'How much energy goes into making the things?'

A surprisingly large amount of energy goes into the manufacture of tiny semiconductor devices.

For instance, researchers from the United Nations University in Tokyo performed a life cycle assessment of one 32-megabyte DRAM chip, tracing it through every level of production, from raw materials to the final product. In doing so, they estimated the total energy, fossil fuels and chemicals consumed in production processes.

The researchers found that each 32-megabyte DRAM chip required 3.5 pounds of fossil fuels, 0.16 pounds of chemicals, 70.5 pounds of water and 1.5 pounds of elemental gases (mainly nitrogen).

While there seems to be no similar studies available on the amount of energy required to produce a single LED bulb, you can make a few rough comparisons between a 32-megabyte DRAM chip and a LED bulb. LED chips also require additional highly refined materials to produce white light. It might be possible that like the DRAM chip, several pounds of fossil fuels are required to produce a single LED bulb, and maybe more.

But LED have a much longer lifespan compared to other forms of lighting, and can provide a tremendous energy savings if used appropriately.

Reference:
Williams, E.; Ayres, R.; Heller, M. The 1.7 kg microchip: Energy and chemical use in the production of semiconductors. Environ. Sci. Technol. 2002, 36 (24), 5504.

[smallpoxgirl]

They are far more efficient on light per watt than any other form.

Sorry to burst your bubble Captain, but LEDs are not particularly efficient. In the worst case, LEDs are about equivalent with incandescents. In the best case they may be competetive with a compact fluorescent. Purpose made fluorescent fixtures blow LEDs out of the water.

[jlpicard2]

Luminous Efficacy (Wikipedia) - artilce lists overall luminous efficacy and efficiency for various light sources.

[Madpaddy]

Don't get mixed up between energy effective and energy efficient lighting. You can put a 1 watt LED in a gym and its very efficient but you can see squat. SPG has it right.

[gg3]

Gideon, you're right. I'm just plain stupid. Not even half-stupid but wholly stupid and with no knowledge of science or tehnology whatsoever. Why I'm so stupid I even reply to ad-hominems.

For exposing my utter stupidity, you win a prize.

Here, have a porcupine.

Now sit on it, gently, so you don't squish it. Ahh, blessed relief!

----

Madpaddy, of course you wouldn't light a gym with LEDs. The point of LEDs is that they can be used in applications where either a) not much light is needed in a room altogether or b) the light source can be close to the thing that needs to be lighted, for example a keyboard or other work area.

I'd sooner have 1.2 watts directly on my keyboard than 25 watts overhead, especially if I'm running on PVs.

As for the total life-cycle sustainability impact of LEDs and semiconductors generally: those impacts need to be compared against the impacts of the things they are intended to replace. For example the number of incandescents or CFs that would need to be used to get an equivalent number of hours of lighting for the intended purpose.

Meanwhile here's a cheap source for a decent LED desk lamp. Search for Innovage, 20-LED lamp. Cost is about $10, he found his at either ACE hardware or one of the big-box lumber/home supply places. A good friend of mine who is a fellow engineer has one and says it's great. Runs forever on a couple of D batteries, and you can use rechargeables.

[Madpaddy]

gg3 wrote,

Madpaddy, of course you wouldn't light a gym with LEDs. The point of LEDs is that they can be used in applications where either a) not much light is needed in a room altogether or b) the light source can be close to the thing that needs to be lighted, for example a keyboard or other work area.

I agree. My point was people get hung up on energy efficient lighting when sometimes it's not very effective. For example in my own house I have CFLs everywhere except in the toilets where my kids go in and out turning on and off the lights every 5 minutes. The good old incandescent is better able to handle this sort of treatment.

[asdar]

I think we'll see more and more applications of LED lighting for the home around. They're developing brighter LED's now and in more color control.

I know I'll never buy another non-LED flashlight or emergency lantern again. I went through two hurricanes that left me without power. In the first one I had an LED flashlight, and some regular flashlights. The LED was on all the time. When the power came back I left it running to see just how long it'd go and it was easily 100 hours.

I read by this light, and the light is steady without flicker and a comfortable level. One of the lanterns I had was compact flourescent and it didn't last close to the time of the LED.

The second hurricane I had two LED lanterns and the flashlight, I never turned them off the whole time and they were still going. My kids take the flashligh out in the dark all the time, they've dropped it from the 2nd floor onto concrete, dropped it into water, left it on all night and probably other things I don't know about and it just keeps right on going.

[Kingcoal]

They are far more efficient on light per watt than any other form.

Sorry to burst your bubble Captain, but LEDs are not particularly efficient. In the worst case, LEDs are about equivalent with incandescents. In the best case they may be competetive with a compact fluorescent. Purpose made fluorescent fixtures blow LEDs out of the water.

They aren't efficient? An LED flashlight has an efficiency of about 15-20 lumens/Watt. Compare that to incandescent at 6 lumens/Watt. In fact, LED traffic lights are far more expensive than incandescent, but have been measured to be 80-90% more efficient and they are brighter and last about 5-7 times longer to boot. Los Angeles saved upwards of 75 million dollars the first year after swapping out all their traffic lights with LED units.

LEDs are far more energy efficient than incandescent and are about neck and neck with fluorescent. They are more versatile than fluorescent, for example, traffic lights would be difficult with fluorescent.

Link

[smallpoxgirl]

They aren't efficient? An LED flashlight has an efficiency of about 15-20 lumens/Watt. Compare that to incandescent at 6 lumens/Watt. In fact, LED traffic lights are far more expensive than incandescent, but have been measured to be 80-90% more efficient and they are brighter and last about 5-7 times longer to boot. Los Angeles saved upwards of 75 million dollars the first year after swapping out all their traffic lights with LED units.

Sorry for the confusion. This thread is about residential lighting.

LEDs are quite efficient in three specific applications:

1. Very low power lighting. A 1/4 watt LED will beat the pants off a 1/4 watt incandescent.
2. Highly directional lighting: e.g. flashlights. LEDs intrinsically have a very narrow beam, so you don't waste efficiency on reflectors.
3. Monochromatic light: e.g. traffic lights or brake lights. Most LEDs intrinsically produce monochromatic light, whereas with other light sources, you would have to use a filter to absorb all but the desired color.

LEDs are not efficient at lighting entire areas e.g. the inside of a house. To get the same efficiency from an LED that you would get from even a compact fluorescent, you are going to have to pay at least an order of magnitude more. No LED outside of a lab can compete with a purpose built fluorescent fixture.

[WisJim]

Everything is not always as simple as it seems, however. Refering to the Wikipedia article linked above, you would assume that a low pressure sodium lamp would be the standard of comparison, but in real live, sodium light fixtures are often being replaced, especially for indoor purposes such as lighting warehouses or gymnasiums, with T5 or even T8 flourescents (not CFLs) in fixtures using highly reflective material behind the lamps. Some advantages include quicker startup (sodium vapor lamps are notoriously slow), longer period of use before replacement is needed due to decrease in light output, easier and cheaper to service, etc.

[IslandCrow]

IslandCrow wrote (elsewhere):

I must pay more attention to what SPG says....I must pay more attention to what SPG says....[snip, because I am sure the monitors would not want me taking up the space repeating this the standard 100 times as a punishment for not listening it the first place]

Dispite SPG's good advice, my curiosity got the better of me and I went ahead and bought the 3W LED screw-in lamp.

It clearly is a very directional light. I tried it as the only bulb in my office. By directing in on to the desk next to the computer it formed a clear circle of light on the desk, giving enough light to work by, and to move safely around the office. I am not sure I liked the light, and my eyes felt a bit strained (maybe that was because I tried it out after my normal bed time). If the LED was to be the only source of non-day light in the office, I would have to move either my desk or the position of the light fixture as the angle of reflection was not good. I will try it a bit more, but first conclusions are: The light would be enough in a major powerdown situation, but for now I will go back to other lighting, at least for the emotional effect of 'not working in the dark'.

A second conclusion (that I will have yet to try out in pactice) is that LED might best fit into the lighting arrangements in my house in places where reading lights are needed (like over the chair in the living room, or as a bed side reading lamp that won't shine in my eyes when my wife can't sleep - not a big problem because I can sleep through most things!)