I just bought a candle-powered electric light, on Amazon. The Luminiser, for $20.
What attracted me to this device, aside from the low price, is that it seems like such an irredeemably stupid concept. Perfect for the headlights on your horse-drawn EV. Or perhaps to replace the light bulb inside your ice-powered electric fridge.
It’s almost as if some nerds took steampunk literally, glommed up a bunch of money via Kickstarter, and created this pseudo-retro-techno-thing. Which is, in fact, how this was developed.
But all that aside, a) it works like a charm, b) the underlying tech is pretty interesting and mostly, c) it’s a vastly more efficient light source than the candle that drives it. And d), I’ve been wanting to own a device of this type for quite some time.
In fact, in terms of in-the-home, fossil-fuel-fired lighting — oil lamps, candles, Coleman lanterns, Aladdin lamps, gas-mantle lamps, and all of that — this is by far the most efficient one you can buy.
So chalk one up for steampunk, as I sit here typing by the light of that lantern, warmed ever-so-slightly by the candle flame in its heart.
In any case, I’m going to use this new toy as my excuse for running the numbers on the entire range of lighting — from candles to LED lights — that I have in my home.
But I’m leaving the deeper moral question for another day. Would the Amish accept this? At root, this two-step light generation process is no different from a mantle-type oil lamp, which is a technology generally acceptable to the Amish.
2000 words (within rounding error) on the Luminiser candle-powered electric light.
The top picture is the lantern, powered by a candle flame visible in the center of it. The bottom picture is that candle, naked.
Edit: Better yet, extremely cheap to run compared to running an LED light using disposable batteries. See next post. And it’s easy enough to use a pint canning jar to make a weighted base and oil candle to replace the proprietary oil candles sold for this lantern. See Post #1931.
It’s a TEG
The manufacturer bills the product as a “light amplifier”. While not technically accurate, you can see how that gets the point across.
In fact, the Luminiser lantern is a thermo-electric generator (TEG) running some strips of LED lights. The candle sits below an internal heat sink connected to one side of some Peltier-junction devices. The other sides of those devices, in turn, connect to an external heat sink. The temperature difference across those Peltier junction devices creates electricity. Which then powers the LED lights.
As a nice touch, the whole thing is enclosed in clear plastic, so you can see the candle burning. But, as is clear from the pictures above, the light from the candle just doesn’t matter compared to the light from the LEDs.
The concept of a TEG is hardly new. In the 1950s, the Soviets manufactured radios powered by a TEG fitted to a kerosene lamp, for use in remote parts of Siberia. NASA began using them in the 1960s to power its spacecraft. For example, Voyager I and II are powered by TEGs. The Martian (of movie fame) famously kept warm using a TEG that generated electricity from the heat created by nuclear decay. Auto manufacturers once toyed with the idea of replacing car alternators with TEGs wrapped around the exhaust pipe. You may have seen (e.g.) TEG-based woodstove fans that run off the heat of the stove. For years, you’ve been able to buy a wood-powered camp stove with integrated TEG, so you can charge your phone while you are roughing it in the woods.
Conversely, a “solid-state refrigerator” or “wine-chiller” or similar is created by running a TEG backwards. Putting electricity into it, instead of taking electricity out of it, causes heat energy to move from one face of the Peltier junction to the other. Face the cold side into an insulated box, and you have a low-powered fridge with no moving parts.
TEGs have always been niche devices. That’s in part because they are finicky. They have to be heated quite a bit, but can’t be subject to extreme heat, and they have to have a “heat sink” (some un-heated area) to dump that heat into. They typically tend to use expensive and exotic materials. And they tend to be an inefficient way to generate electricity, converting at best between 7% and 8% of their heat input to electricity.
Really, the only thing shockingly new about this device is the price. Prior to this, other than D-I-Y projects, you’d be talking about at something like $200 to get even the simplest TEG-based light source or low-wattage generator. This thing is $20. Candle included! It’s cheaply built, for sure. But it works.
How efficient is this, as a light source, or, faster than the person you’re hiking with.
Picture this: You’re walking in the woods with a companion. You accidentally stumble across a sow bear and her cub. She takes your presence as a threat, so she charges at you, with the clear intent to kill you. How fast do you need to be able to run, to outrun that bear?
The point being that while a TEG is a somewhat inefficient way to generate electricity, a flame is an incredibly inefficient way to generate light. In this application, the TEG doesn’t need to be able to outrun the bear, it just needs to be able to outrun the competition. Which, as it turns out, isn’t all that hard.
A candle converts maybe 0.05% (not a typo, five-hundredths-of-a-percent) of the energy of the fuel (wax or oil) to light. The remaining 99.95% (still not a typo!) of the energy escapes as heat. I went through this in detail in Post #1615, Candles versus Batteries, where I figured out why they no longer sell candle lanterns in shops catering to backpackers. (Answer: It’s now vastly more efficient to carry batteries than to carry candles.
An efficient Peltier device — the heart of the TEG — might be able to convert 8% of a stream of waste heat into electricity. (I’m too lazy to give a hard cite for that. Trust me.) But at this scale, I’d guess the conversion is closer to half that.
The most efficient LEDs might be able to convert 30% of that electricity to light. But here, I’d knock that back to 20%, for a closer guess. Plus you have to run a bit of electronics to deal with the varying input from the Peltier devices.
The resulting estimated efficiency of the conversion of heat to light in the Luminiser probably clocks in around 4% x 20% = 1.6%. Pitiful, yes, but that is somewhere around (1.6 / .05 =) 30 times as efficient as the candle, at generating light from the underlying fuel. In the ballpark of the 20x figure claimed by the manufacturer.
Check that figure: First, the manufacturer claims that it’s 20 times as efficient. So we’re in the ball park. But yet a third way to check this is to compare the rated output and fuel consumption, as stated by the manufacturer, with the known performance of a candle. They claim 150 to 200 lumens, for 8 hours, using the provided 44 milliliter oil candle, or (200 x 8 = ) 1600 lumen-hours of light, from 44 ml of oil. As a candle, the 44 grams of fuel would produce about 70 lumen-hours of light (calculated from Post #1605, cited above. Thus, based on rated output, the Luminiser is (1600 / 70) = about 23 times as efficient a source of light as the candle that fuels it. Again, very much in line with the manufacturer’s claims.
The upshot is that this little lantern conservatively produces at least 20 times as much light as the candle that heats it.
The Luminiser is vastly more efficient than an Aladdin (r) lamp.
Big deal. As a light source, candles suck, as anyone who has ever tried to read by candle light will tell you. There’s a reason that candelabras — fixtures designed to burn many candles at once — exist. And it ain’t for decoration. That was a practical response to the low light output of a single candle.
For sure, the standard for in-the-home oil-lamp efficiency is the unpressurized incandescent mantle lantern. Which, in the modern world, means an Aladdin (r) lamp, as they are the last manufacturers of those in the world. In such a device, instead of burning oil for light (as in a traditional flat-wick oil lamp, or the slightly-improved center-draft oil lamp), the oil is burned for heat. It heats up a “mantle” typically made of thin threads of some sort of ceramic oxides, causing the mantle to glow (incandesce) — that is, to emit visible light. Like the Luminiser, the Aladdin (r) lamp does not use the fossil fuel to produce light directly. Both devices use indirect processes, converting the heat from burning the fossil fuel, into light.
To work out the arithmetic (again, without hard citations as to source here), you have to know that a) an Aladdin lamp puts out about 1000 watts of heat, on high, and b) under ideal circumstances, using older Thorium-based mantles, that same lamp puts out as much light energy as an old-fashioned 60-watt incandescent bulb.
(You can derive the heat output in watts from a fuel consumption of roughly 3 ounces of kerosene per hour. Just math, plus conversion factors. The 60-watt-bulb thing, that’s by eye, but pretty much every savvy user says roughly the same thing. Rumor is that the newer mantles — those lacking the slightly radioactive thorium — only produce as much light as a 40-watt incandescent bulb. But shove all of that under the carpet for now.)
Old-fashioned 60-watt incandescent electric lights produced about 800 lumens of light, and were only about 5% efficient, at best, at converting electricity into light, rather than heat. That means a 60-watt old-fashioned incandescent bulb produced, at best, (60 x 0.05 =) 3 watts of light energy.
Oddly, manufacturers seem to have been busy rewriting all the statistics on light source efficiency. That 5% figure was what I recall from many, many analyses of this topic, over the years. But I now stumble across internet sources claiming that incandescents are 10% efficient and LEDs are 90% (!) efficient. I have no clue what they are doing to get those numbers, or how they could possibly justify them. But by those metrics, if LEDs improve only a little bit more, they’re going to be more than 100% efficient. Which pretty strongly suggests some there’s some serious bullshitting going on.
In any case, you can work up your own calculation based on known data of 60 watts of electricity, and 800 lumens of output. Lumens are an odd measure of power, in that they are adjusted to match the sensitivity of the human eye. So to do the conversion, you either have to assume some known frequency of light being emitted, or some standard spectrum. (For example, famously, those orange-colored sodium-vapor street lights produce a lot of light energy, but not so many usable lumens, because the human eye isn’t very sensitive to that color.) Per Wikipedia, one watt of green light — the peak of human eye sensitivity — produces 683 lumens. But incandescent bulbs tend toward the red end of the spectrum, where the eye is about half as sensitive. This site provides an excellent table and chart showing that, in the form of the number of lumens produce by a single watt of light energy, at various colors (frequencies). Thus, an actual physics-based watt of energy, emitted as light, by an incandescent, likely produces about half that many lumens as pure green light, or (say) 340. That means the “60 watt” electric light bulb produces somewhere around (800/340 =) 2.4 physical watts of light, across the visible spectrum. This would make a typical yellow-red glowing incandescent electric light bulb roughly (2.4 / 60 = ) 4% efficient at converting watts of electricity to watts of visible light, completely in accordance with the long-established rule-of-thumb of 5%. How manufacturers now claim that incandescent bulbs are 10% efficient is beyond me. Perhaps they are referring to recently-developed products. They sure aren’t referring to the garden-variety light bulbs of my youth.
Thus, an Aladdin lamp is about 0.3% efficient. It produces around 3 watts of light energy, for 1000 watts worth of fuel burned. This does not sound like much, but that’s about seven times as efficient as a candle or a traditional flat-wick non-incandescent oil lamp.
But an Aladdin lamp is nowhere near as efficient as this little TEG-based lantern. The Luminiser is about (1.6 / 0.3 = ) 5 times as efficient as an Aladdin lamp, at converting the energy in oil to light.
Check the calculation. I can check that by converting the 44 ml of oil in the Luminiser candle to Aladdin lamp burn time, at a typical 3 ounces per hour. In round numbers, the oil in a Luminiser oil candle would produce about a half-hour of run time, for an Aladdin lamp putting out possibly 800 lumens, or about 400 lumen-hours of light. But as calculated in the prior section, that same candle produces about 1600 lumen-hours of light in the Lumeniser. Thus by that calculation, the Luminiser is four times as efficient a light source as the Aladdin lamp.
By eye, that seems completely plausible. For a while, I had the Luminiser burning next to an elderly Aladdin (r) lamp. For illuminating the table-top, the Aladdin on low was about the same brightness as the Luminiser.
Finally, pressurized oil mantle lamps (E.g., Coleman lanterns, here in the U.S.) are said to be as much as twice as efficient as unpressurized Aladdin (r) lamps. Even so, based on my calculation, they’d be no better than half as efficient as the Luminiser. And those are not fit for indoor use, anyhow.
All of which is inefficient compared to electric lights
I don’t want to lose sight of the fact that normal electric lights are far more efficient than candles, oil lamps, or this TEG-powered Luminiser lantern.
Modern LED bulbs are said to be as much as 30% efficient at converting electricity to light.
(Again, manufacturers seem to have shifted the basis of measurement lately, as some are now claiming that LEDs are 90% efficient. I will once again point out that if there is any material continued improvement, they’ll soon find themselves producing LED lights that are more than 100% efficient, by whatever bullshit system they are using to come up with those numbers. So I’m sticking with more traditional, and internally-consistent, estimates of efficiency by type of lighting. And that places the best modern LEDs around 30%, where the best old-fashioned incandescents were 5%, and CFLs typically came in around 20% efficient.)
Couple that with grid-based generate that typically converts 30% (coal) to 50% (natural gas) of the energy in the input fossil fuel into electricity, and the overall efficiency of grid-based LED lights, on a fossil-fuel-fired grid, has to be somewhere around 9% to 15%. That is, between the time the coal is dumped or the natural gas is piped into the power plant, and the time you light your house with the resulting electricity, you will have converted 9% to 15% of the energy value of the underlying fossil fuels into light.
Compare that to 1.6% for the Luminiser. The difference is due to the relative inefficiency of TEG electrical generation (4% to 8%, say), compared to coal-fired boilers and gas turbines (30% to 50%, say).
CHP caveat.
But I only get the urge to burn stuff in the winter. In that case, the overall calculation gets blurrier, because I welcome the heat from the flame, in my home.
Without going into the full song-and-dance, an Aladdin lamp, burning in a cold room, is the old-fashioned equivalent of a combined heat-and-power (CHP) generating unit. Which, in turn, is just any unit that burns fossil fuels to make electricity, and then uses the waste heat to warm your house or other living space.
The upshot is that if you don’t count the heat as wasted energy — if you calculate the efficiency of a candle or oil lamp as a CHP unit, not just a light source — then your oil lamp looks a lot more efficient. When I grind though the calculation of an Aladdin (r) lamp versus gas-fired grid powering a modern heat pump, the gas-fired grid still wins. But it’s a lot closer than the calculation for light alone.
Unnecessary background: A flame-based cure for the winter blues.
Source: According to AI, all cavemen look vaguely like Kurt Russell. I’m not sure why. I expected to see the Geico guy.
Two hundred years ago, my humble abode would have been considered a palace, a place of miraculous luxury unobtainable by the common man. Lights and heat at the touch of a switch. Running water, hot and cold.
Flush toilets.
And yet, during the darkest months of the winter, something is lacking. With the short days, and the bitterly cold nights, I get the urge to burn.
The caveman wants his fire. I’m not proud of it, but this time of year, my heating and lighting energy sources tend to devolve from electricity to wood, wax, oil and kerosene.
It’s an unhealthy habit, for sure. Burning anything inside your house isn’t very smart. So I try to keep it within reason. If you can smell it, it’s too much.
Lighting your house with flames is obscenely inefficient. An oil lamp, for example, is a kerosene heater that, as a minor byproduct, also manages to produce a tiny bit of light. And candles, as a light source? Been there, done that, got the ill-lit t-shirt (Post #1605, Candles Versus Batteries).
But somehow, those flames are just really satisfying, in a way that LEDs are not, when it’s cold and dark outside.
With the Luminser, I get a little bit of both worlds. I get to see the flame at its heart, and I get a decent amount of light. A nice compromise, for this time of the year.
You know what they say. Better to light one candle — and to use the waste heat to run a TEG to illuminate banks of LEDs, thus vastly increasing luminous efficiency — than to curse the darkness.
