LED lighting— yet more green BS
I haven’t done any green-baiting lately and I really miss reading the hundreds of comments from people that call me an idiot or a shill for the oil companies. Last week I was with my buddy Paul Tuttle at his monthly HP alumni gathering. One of the HP retirees bragged about how he was using LED bulbs in his house and how they lasted longer and saved energy. Now I try to keep up on LED lighting— it is a promising technology, but in 2008, the situation is this: Cree, a great outfit has managed to exceed the luminous efficiency of cold-cathode fluorescent but only in a tiny 20 mA LED. It puts out way less light than a CCF. OK, what Cree has done in their big lamps is to match the efficiency of halogen, at least in the lab. They are still a ways off from getting the same luminous efficiency as a fluorescent bulb. Now there are great applications for LED lighting. One is inside food coolers it the grocery store. Since fluorescents don’t work very well when it is cold they cannot be used. And the incandescent halogen lights might use the same power, but they also reject more heat into the cooler, and it takes refrigeration energy to make up for that. On top of that you don’t have to replace the LED lights as often and that is always good in a business situation.
Another great application for LED lights might be way up on a high ceiling where it is a real pain to get up there to replace the lamp. But be careful about lifetime claims for LEDs. First off, bear in mind that heat degrades an LED. The end-of-life may not be a failure, but rather, a reduction to 50% output. Also lets not forget you need a power supply to feed the LEDs. If you want any kind of efficiency, that has to be a switching supply with an IC and worse yet, electrolytic capacitors. You are not going to get 60,000 hours out of that in all cases. We all know that the early CFL lamps would die early if you switched them on and off a lot. That was not the phosphor or the bulb failing, it was the little power supply in the base. In addition to the lifetime issues of a power supply realize that the power supply is a big hit on efficiency. Yeah, you may run an LED string on AC with a resistor, but you will get really lousy efficiency. The same goes for making it dimmable, it will work but you will take an efficiency hit.
What really irks me is the plain old marketing BS surrounding LED lamps. Paul Tuttle told me about this great site, C Crane. We all gotta love a site that has short-wave radios and scanners on the home page. The problem is on the LED light page. There they have a little chart to show what a great deal LED lights are and how one bulb can save you 353 dollars and 25 cents. But it is a bald-faced lie and all it takes is a few minutes on the Internet to prove it. It took a few seconds to find this page with a halogen lamp that makes 840 lumens, uses 60 watts and lasts 3000 hours. When you plug this into the little chart at the bottom of the C Crane page you no longer get a $353.25 savings, you get a $217.50 penalty.
|Incandescent 60 Watt Light Bulb||CC Vivid 2 Watt LED Light Bulb||Real incandescent bulb||Real LED system||CFL|
|Life Span (hours)||1,000||Up to 60,000 hours||3,000||Unlikely 60,000 hours||8000|
|Number of bulbs used over 60,000 hour period||60||1||20||14||7.5|
|Bulb Cost per 60,000 hours||$40.20 (67¢ each)||$34.95||$79.80 (3.99 each)||$489.30||$18.75 (2.50 each)|
|kWh of electricity used over 60,000 hours||3600 kWh||120 kWh||3600 kWh||1680 kWh||780 kWh|
|60,000 hours at 10¢ per kWh||$360||$12||$360||$168||$78|
|Total cost after 60,000 hours||$400.20||$46.95||$439.90||$657.30||$96.75|
|Money saved (or lost) by installing one CC Vivid LED Light Bulb||Save $353.25 Per Bulb! (lie)||Lose $217.50 per installation!||Save $343.15 per installation|
The first issue is that the halogen puts out 840 lumens and the LED puts out 30. So you need 14 LED lamps to get the same light as a 60-watt halogen. (You can save a lot of electricity using candles too.) I added the three right-hand columns to show the real deal. I used the $3.99 cost from the Lamps Plus website for the 60 watt incandescent cost instead of $0.67 that the chart shows. That is only fair to the LED light. I also got the numbers for a compact fluorescent bulb (CFL) from this website. Note that the CFL also rejects less heat into the room so if you use air conditioning you save with CFLs, just like you would save with an LED system.
But there is even worse news. I pointed out that LED bulbs degrade over time. Manufacturers want to run them hot since that lowers the forward voltage and increases efficiency, but the heat also kills the LED. So if my suspicions are correct and 60,000 hours life is to half-brightness, that means you have to multiply LED lamp costs by 1.5 to get the real cost penalty, at least if you want the same amount of lumen-hours from both systems.
And let us not forget the time value of money. The LED system makes you spend $489.30 right at the beginning. If you put that in the stock market at 6% return (or paid off your 6%, 30-year fixed mortgage), you could make $29.36 a year. That would pretty much buy all the incandescent lamps. If you use the lamp 8 hours a day that is 21 years of opportunity cost, nominally $616.56 but remember that the opportunity cost is also compounding , so if you use a compound interest calculation, the $489.30 up-front costs you a total of $1663.41 cents over the 21 years you could have had it in your equity account. Compound it 12 times a year and you get $1719.58. That will buy a lot of incandescent light bulbs and the electricity to feed them. Sure you will be drawing down your savings with the cost of the incandescent replacement bulbs and greater electricity, so you really don’t save 1700 bucks, — but you still lose with LED lamps when they are this expensive.
And you have to remember that the 60,000 hours is just a guess. None of these LED lamps have been run for 7 years straight to verify the lifetime. And I assure you the power supplies may well die before the LED. This is just as true for fluorescent lamps. I thought I was saving money with an electronic ballast 8-foot fixture in the megaplex. But it failed after 5 years and the cost to install a new ballast was far greater than the savings in electricity. Complexity and electronics can save power in the short run but if it costs you more money over time it is not being green, it is being wasteful. And look at this website. It has incandescent lamps that last 20,000 hours. Now the way I know how you do that is to oversize the filament, so I have to believe these bulbs are less efficient. But how about those 5,000 hour bulbs the website also mentions? I wish they had lumens output so we could do that comparison but that is a task for later. If you use 5,000 hour bulbs you only need 12 of them over those 21 years and they are just as bright when the are old as when they are brand new.
The final caveat about the LED lighting chart above is the claim that they can get 30 lumens for a 2-watt bulb. That is about twice as good luminous efficiency as the halogen. I doubt that is really what is going on. Perhaps I will buy one and measure its output. That is not easy since you have to integrate the output over the entire sphere of operation. Having a spot-light source may help in certain application but to be fair to fluorescents and incandescents we really have to look at the total lumens output from all three lamp systems.
Now I do want all you crazy greens to comment and call me a fool and work yourself into a self-righteous religious furor, but you should know I really do respect and love you all. I think most every one of you are good decent people who are wise enough to know that we have to use technology to save energy as much as we can. This is why I get so pissed off when people lie and you nice folks actually believe them. Marketing is based on that great principle—“just lie”. It worked for Hitler, it worked for all the con artists, it works for the used car salesman with his plaid jacket, firm handshake and big smile as he says “Damn glad to meet you!” You bet he is. He is about to rip you off.
But saving the planet is too important to let the confused or the con artists have their way. Greens need to understand a few basic principles of economics. One is that if something is cheaper in total time-adjusted cost, it is better. This means that you have to put a time-value on money. That is real, that is a law, not some half-baked theory or fever-dream hypothesis. If you can save money popping in incandescents for 21 years then they are better for the planet. (Actually you can see CFLs are currently the best by far.) That is why I believe in conservation, not conspicuous green consumption. Bob Pease saves a lot more of the planet driving a 1969 Volkswagen Beetle than a brand new $60,000 hybrid. Taxing the populace to pay some of us to put up solar panels the way Germany does is not good for the planet. It is wasteful and evil.
Here is a great site about LEDs and incandescent lights. And here is part one and part two of a nice interview with Silicon Valley legend TJ Rogers of Cypress Semi and Sunpower. He pretty much admits that you need subsidies to justify solar power. He seems to think that we are just about to turn the corner on economic viability. We shall see, my buddy Frank Fowler just put 30 grand worth of panels on his home and I will let you know if that drives his electricity bill to zero. Oh, and we all know wind power does not really kill birds, other than when it does kill a lot of birds.
Solar power is a great technology and I know of some start-ups that are going to make it economical. When that happens I will be solar’s biggest booster. If LED lights can really compete with CFLs I will be all for them. Right now, you are better off just turning off the light if you don’t need it and try to minimize your driving. That is conservation, and that has always been a good thing.
[Update] The Cree marketing manager wrote me a detailed refutation of this post I will put up later, but he was also bothered by my description of marketing– for that I apologize, I was not referring to the marketing departments of 1st tier companies like Cree and my pals at all the analog companies, it was these web marketers like C Crane that ticked me off.