STOP PRESS: Pixie dust unsuitable for household lighting

A reader pointed this page out to me, about the recent Greener Gadgets Design Competition $1000-second-prize-winning Gravia "floor lamp powered by gravity".

Gravia lamp

It's a funky looking thing, which was widely reported around the gadget blogs, and was alleged by its designer, Clay Moulton, to give the equivalent light output of a 40-watt incandescent bulb for four hours from the energy of a weight dropping about four feet, or 122cm. When the weight gets to the bottom, you just lift it back to the top and away you go again.

Now, it stands to reason that a mere 1.2-metre drop isn't going to give you forty actual watts for four hours unless the weight is incredibly heavy. Ignoring losses, it would by definition take forty watts of power over another four hours to lift the weight back up again, which is 160 watt-hours, which is quite a lot. A normal adult human in reasonable shape can manage about 75 watts of output when pedalling away on a bike connected to a generator; it'd take more than two hours of such pedalling to raise that weight back to the top of the Gravia light's tube, if the weight were heavy enough to make a constant 40 watts on the way back down.

So I just assumed the lamp's brightness was greatly overstated, and wasn't even four-watts-of-LEDs-that-are-sort-of-equivalent-to-forty-watts-of-incandescent. But since they'd clearly actually made the thing and it'd won an award, I presumed it did work, if only as a night-light. Fair enough.

But neither Clay Moulton nor anybody else has, actually, built a Gravia.

The damn thing doesn't exist.

And Mr Moulton, who apparently designed the thing as part of his Virginia Tech master's thesis, didn't even bother to check whether his design could possibly bloody work at all, even if you built it with LEDs from ten years in the future.

Looking at the schematic for the Gravia shows that the falling weight is defined as fifty pounds, which is 22.7 kilos, which is indeed about as much as a variety of humans could reasonably be expected to be able to lift back to the top of the tube every few hours.

22.7 kilograms falling 1.22m in gravity of 9.8 metres per second squared gives you a grand total of 271.4 joules.

That, once again ignoring losses (which are likely to be considerable, seeing as there's a ball-screw and an electrical generator in the Gravia), will by definition run a one-watt lamp for 271.4 seconds, or four and a half minutes.

If you downgrade the lamp to one tiny 0.1-watt LED night-light, you get three-quarters of an hour.

The maximum possible luminous efficacy for any kind of lamp that will ever exist - if every quantum of energy going into the thing is used to make visible photons that come out - is 683 lumens per watt. And that's for a lamp that emits monochromatic 555-nanometre green light, not white (the world record for white LEDs in the lab so far is less than 150lm/W), but never mind that for now.

So if your tenth-watt lamp is just such a perfect device that can never actually exist, it will emit 68.3 lumens of light.

There's no standard lumen rating for an incandescent 40-watt bulb - generally speaking, the ones that last longer have lower output - but something like 400 lumens is in the ballpark. Actually, the Gravia has been alleged to output 600 to 800 lumens, but even if you only shoot for 400, 68.3 lumens is 17% of the target.

So instead of the output of a 40-watt incandescent bulb for four hours, we've got the output of a 6.8-watt incandescent bulb for 45 minutes. And that's with a perfect lamp and no other losses in the system. With the best white-light lamp that humans will actually ever be able to make and million-dollar hardware for the rest of the thing giving the lowest possible losses, I think you'd actually be talking the output of a two-watt incandescent flashlight bulb for about 30 minutes. At best.

Looking at it from another angle, 271.4 joules is 271.4 watt-seconds, 683 lumens per watt is the physical limit, so by definition 271.4 joules of energy can only produce 185,366.2 lumen-seconds of light. Four hours is 14,400 seconds; 400 lumens for four hours is 5,760,000 lumen-seconds. So 271.4 joules into a perfect lamp can only possibly ever give you 3.2% of the required light. Or 1.6%, if you take the 800-lumen ceiling figure for the Gravia's output.

These facts have not evaded other observers, and have now also been communicated to the Gravia's designer. That pesn.com page now features, in the comments, about a minute worth of these back-of-an-envelope calculations that anybody with a basic physics textbook could have done, and it also now features an apology from the designer of the Gravia, who now concedes that the thing could not actually be made and that he did not deserve, and will be returning, the prize.

Actually, I reckon he did deserve the prize, since the Greener Gadgets people are clearly a bunch of idiots (see also: The New Inventors) and their prize is therefore worthless.

I hereby propose magical light paint, which glows harmlessly at 200 lux for 500 years (power source: A D battery filled with the blood of saints) and costs a buck a gallon. Tah-daaah! I just won first prize in the next Greener Gadgets Design Competition! Drop me a line, guys, and I'll tell you where to send the money!

The original press release about the Gravia on the Virginia Tech site now also contains a disclaimer from Moulton, though without any mention of him giving back the prize. I think it's worth mentioning one line he uses on both pages, though: "I was told it was not possible given current LED's, but given the rapid pace of innovation in low powered lighting, it would be a conceptual challenge."

Yes, Mr Moulton, it certainly bloody would be a "conceptual challenge" to make a lamp that produces more than thirty times as much light as the laws of physics say is possible from the energy you put into it. That would be a pretty damn impressive achievement. I propose Virginia Tech not permit you to graduate until you do it. How's that grab you?

The Gravia is very far from alone, of course. There's a veritable plague of these entirely imaginary "concept" devices. The gadget blogs are rotten with 'em. But usually these things have the decency to obviously just be a 3D render of some stupid concept that couldn't possibly work (image-intensifying sunglasses, say...). Sometimes it looks as if at least a mock-up has been created. Only seldom does an impossible device actually win an award for "design innovations for greener electronics".

(I suppose a lamp that doesn't work is, in a manner of speaking, quite "green". It reminds me of that Goodies episode in which string is a "safer and cheaper" subsitute for electrical wiring, "because it doesn't work".)

One bit on the Gravia's design competition page is particularly priceless: "Gravia is also [a] metaphor for an understanding of social activism."

Yes, Clay, it is. If you just sit on your arse and make shit up without paying any attention to the actual nature of the world, you will not succeed in social activism or lamp design.

Thrilling LED bulb replacement action!

LED lamps for standard low-power automotive sockets - things like interior lights, number-plate illuminators and brake lights - are now widely available and dirt cheap.

So I bought one, to see if it works any better than the standard interior light in my car.

There was nothing wrong with the standard interior light, but like a lot of low-power automotive bulbs, it's offensively inefficient.

The bulbs used in cars for things like interior lighting and instrument panel illumination have as their two chief design goals cheapness and durability. Both of these goals push manufacturers towards very low-efficiency devices. And the standard "dome" light in the middle of the ceiling of most cars generally doesn't even have much of a reflector behind its bulb, so something approaching half of the light just goes into warming up the light fitting.

So the dome light in my car looked like a fine candidate for LED improvement to me. Particularly now that one lamp will only cost you $AU8.98 delivered from Hong Kong.

(I got mine from this eBay seller.)

My car's interior light uses the small 31mm size of "festoon" bulb, the kind that look like a glass fuse but with points on the metal caps on each end.

The 31mm form factor doesn't give a lot of room for modern super-LEDs. You can now get 31mm lamps with a single allegedly-one-watt white LED in them...

LED bulb

...or you can go for the type I got, with no fewer than six surface-mount sub-1-watt super-LEDs.

There are also replacement bulbs that use a cluster of standard 5mm LEDs. They may be OK for things like instrument panel lighting, but you shouldn't expect as much light as you'll get from a single 1W LED unless there are at least a dozen 5mm LEDs in there. Even then, it's doubtful.

LED bulb detail

If you don't see a lot of yellow phosphor looking back at you, you're probably not looking at a very bright lamp.

I gave the new bulb a whirl on my bench power supply to see how much power it consumed. Then I tried the same thing with the (rather old) stock bulb.

The LED lamp drew only about 55 milliamps (mA) at twelve volts, for a power rating of only about 0.66 watts. Raising the supply voltage to 13.8V - which is what you'll get when the car's running and the alternator's turning - raised the current draw to about 105mA, for 1.45 watts.

The stock bulb has a nominal ten watt rating. From 12V it drew around 0.725A - that's 8.7W. From 13.8V it drew only a little more, about 0.785A (this is because the resistance of light bulb filaments rises with their temperature), giving 10.83 watts.

I expected the LED lamp to deliver much more light per watt than the incandescent bulb, and it also gets a big effectiveness boost from only throwing light out one side, wasting none of it by shooting it uselessly into the dome light fitting. But this was still a pretty huge power difference. At 13.8V, the old bulb draws 7.5 times as much power as the LED lamp; at 12V it draws more than thirteen times as much.

It was pretty easy to install the new lamp, although it did turn out to be a bit longer than it was supposed to be, making it a bit of a tight fit and also making it impossible to install it perfectly level. It ended up tilted a bit toward the left seat, though not enough to make a huge difference to the illumination on the two sides.

To cancel out any side bias, I tested the brightness of the two lamps with my somewhat accurate light meter sitting at the base of the gearshift (and with the standard plastic diffuser in place, too).

The light meter is calibrated in lux, a unit that's weighted to match human brightness perception. This gives the LED lamp another advantage, because the long-life low-temperature incandescent bulb gives very yellow light, while the LED lamp gives the characteristic blue-white of "white" LEDs. The blue-white has more energy around the green frequencies where human vision works best, so a given raw energy level of yellow-white light will appear dimmer, and read lower on a luxmeter, than the same energy level of blue-white.

Anyway, the stock bulb gave a reading of about six lux with the engine off (12V), and about nine lux with the engine running. Not a bad illumination level, given that it was being measured quite a bit lower than the place where you'd typically be, say, holding a map you were trying to read.

Swapping in the LED lamp gave... exactly the same readings!

My light meter isn't terribly accurate down in the single-digit lux, so I won't swear to you that there wasn't actually a bit of a difference one way or the other. But there clearly isn't a huge difference. And the new lamp, subjectively, lit up the cabin of the car just fine. Despite drawing around a tenth as much power.

This sort of thing can make a big difference in certain circumstances. If, for instance, you have a typical small car battery with about 25 amp-hour capacity before it starts getting very unhappy, a ten-watt interior light will drain it in thirty hours. Swap to a one-watt LED lamp and you'll probably still be able to start the car even if you leave the light on for ten days.

This doesn't matter much for normal automotive interior lighting, but if you've got a caravan or motor home or something that has a lot of friendly yellow incandescent bulbs in it, it could be a very good idea to swap them for the new cheap LEDs.

More perpetual motion - with video this time!

A couple of people have forwarded this article to me, about a fellow called Thane Heins who seems to be claiming (in essence) that he's made a motor with better than 100% efficiency.

I, of course, will believe it when I see it. And I don't expect to ever see it.

But the hook in the article is that Professor Markus Zahn of MIT was impressed - or at least confused - by the demonstration.

There's no real information about what actually happened in the demonstration, though. The closest they come to telling you is saying "He holds a permanent magnet a few centimetres away from the driveshaft of an electric motor, and the magnetic field it creates causes the motor to accelerate."

Well, yeah. Of course it does.

If you put stronger magnets in a permanent magnet motor, it'll give you more power from a given voltage. And consume more current. Its efficiency will probably actually drop.

And you certainly can demonstrate this effect by moving a powerful magnet close to a motor, such that the field from the external magnet supplements the field from the magnets inside the motor.

Behold, My Very First Metacafe Video, demonstrating the phenomenon with an unsuspecting motor and a honkin' great magnet:


Over-unity Motor Demonstration... Not!

Note the current and voltage displays on the power supply that's running the motor. The voltage stays where I set it (when it's not being pushed around by back EMF when the motor slows down), but the current - and thus the consumed power - spikes massively when I'm "supplementing" the motor's own magnetic field.

You can do this same thing more efficiently if you replace a permanent magnet motor's internal magnets with more powerful versions. But a field is a field; the motor doesn't much care where the field comes from.

This is why, for instance, there are restricted model car and aircraft racing leagues that only let you use cheap ferrite-magnet motors. I remember a friend telling me about a dude whose plane was faster than everyone else's and nobody could quite figure it out, until they noticed that the "magnetic latch" on his battery bay, right under the motor, contained the most powerful rare earth magnet ever used for such an application.

I hope there's something more to Thane Heins' discovery than this, but I wouldn't be at all surprised if all he's done is embroidered on the idea by, say, switching electromagnetic coils outside a permanent magnet motor to put the field supplementation where it'll do the most good at each point in the motor's rotation. Which also won't give you any more efficiency than a number of existent motor designs.

Here's Thane himself, explaining his invention:

I don't know enough about this stuff to know whether what he says makes any sense at all, but I suspect he's asking back EMF to do things that it won't actually do.

Revolutionary Sonic Boiler Probably Not A Scam!

Peter Davey

A reader asks:

Hey Dan,

Tell us about this thing please. Can there be that much transfer of energy so quickly?

Steven

Well, we don't really know how quickly Peter Davey's "sonic boiler" is supposed to be working. The article says it boils the water "within seconds", which is a bit of a fuzzy definition. I'd like to see exactly how fast it actually does boil it.

And if you want to transfer energy to a liquid, hitting the resonant frequency of that amount of liquid in that container is actually not a good way to do it. That'll just spray water up the walls. And talk of "resonances" is of course practically diagnostic of crackpottery.

But, making the usual allowances for scientific illiteracy in the popular press, it's possible that someone could have come up with a way to dump energy into water faster than your normal immersed heating element can do it.

Immersed elements are already pretty darn good, though.

The "2200-2400W" electric jug in my kitchen will bring half a litre of water to a good enthusiastic boil in about eighty seconds, and it draws as much power as you can get from the maximum ten-amp-per-socket current rating of 220-240V countries like Australia and New Zealand, where this inventor resides.

The sonic boiler could be running at 15 amps or more, but that's cheating; 15-amp sockets are special equipment (used for things like air conditioners), and anybody can boil tons of water in half a second if they're allowed to use as much electricity as they like.

About 500ml is the minimum amount you can put in most electric jugs without leaving some of the heating element hanging in the air to overheat. It's also two mugs worth of liquid. So, as Peter Davey says, people certainly do often boil more water than they need. But making an electric jug of conventional design that can heat one mug worth of liquid is not a great engineering challenge. Let's do the sums and see how fast such a jug could perform, in Physics Experiment Land where pulleys have no friction and cows are spherical.

The (physics, rather than dietary) calorie is the amount of thermal energy necessary to raise the temperature of one gram of water by one Celsius degree. So if you start with 250 millilitres of water at 25°C (which means almost exactly 250 grams of it) and need to raise it all to 100°C, you need 75*250=18,750 calories, which is 78,450 joules.

A joule is a watt-second. So if you've got a 2400-watt heater that transfers heat with perfect efficiency to water, you must run it for 32.7 seconds to do this job.

Taking that into account, my electric jug is, clearly, not that far from the theoretical maximum water-heating efficiency.

Assuming its element could be fully submerged in only 250ml of water, that water would boil in about forty seconds, which is only 1.22 times the Physics Experiment Land time for the job.

Given that the element has to heat up from the inside out, and that some energy is lost through the walls of the jug, and that some more is lost to internal evaporation and sound and so on, this electric jug is clearly working about as well as it even theoretically could, when you take real-world limitations into account. Some other 2400-watt heater, built in such a way as to be less limited, could only possibly do the job in 82% of the time, unless it was magically getting energy from nowhere. And Peter Davey does not appear to be making any such claims.

(I'm also assuming that he's not cheating by pre-heating the boiler before it's dipped in the water. It's not hard to boil water "instantly" if you drop a red-hot rock in it.)

So I say good luck to this bloke. He may well have come up with a genuinely new and interesting heater element design, which may have advantages over existing bare immersible heaters, which are generally rather dangerous things. And his heater may work very nicely with even small amounts of water, which in itself is a step forward; you can get electric kettles with the element built into the baseplate which work with arbitrarily small amounts of water, but they take longer to heat up in the first place because of all the extra metal around the element. There may indeed be a niche for this sonic heater, if it performs as advertised.

But there ain't no such thing as a free lunch. If the sonic heater works very much faster, in seconds-per-gram terms, than any old discount-store electric jug, then it's another perpetual motion machine, which would have a few applications beyond just making a quick cup of tea.

Another overpriced heater

Hot on the heels of my post about the rather audacious "Amish" fan heater, came this:

I've been seeing commercials on TV that proclaim the advantages of a certain compact heating system that uses some sort of mixture of infrared lamps and a heat exchanger. They also claim, like the "Amish" heater people, that it uses less electricity than a coffee maker.

Now, I live in a 120+ year old house, and I'm quite... thrifty. Given the rise in natural gas prices, this of course piqued my interest.

The "Portable Furnace" is a similar product to the one in the ads.

Still, something sounds off here. I remember in my grandparents' old cottage they had a heating lamp of some description in the bathroom, over the spot one would be when one stepped outside of the shower door. It worked well then, but move a few inches either way and it was quite useless.

Smoke and mirrors?

Joe

I'll be darned if the "Portable Furnace" isn't just another surprisingly expensive ($US599!!) 1500-watt fan heater.

It's a nice-looking one that probably doesn't make much noise and may last longer than the $10 discount-store type, but it's still essentially the same thing. And, once again, the ads are trying to trick people into thinking it's something special, when it really, really isn't.

I can say this with such confidence because basic physics tells us that all resistive electrical heaters are, to a first approximation, exactly the same.

In a resistive heater - actually, in any electrically powered device at all - each watt of electricity ends up as one watt of heat. End.

You can change exactly how a heater delivers its heat to the room - as infrared light, in the case of a simple old-fashioned "bar" heater with a reflector, or as a rising column of convective hot air, in the case of an oil-filled heater, or as a hot breeze, in the case of a fan heater. You can even get all tricky and add a ceiling fan, probably spinning in the opposite direction to the way it spins in summer, to suck air up in the middle of the room and blow it down the walls, thus preventing hot air from gathering up by the ceiling where nobody is sitting.

But the base efficiency of the system is exactly the same for all electrical heaters.

The allegation that the Portable Furnace's heating elements are in some way special because they're big light bulbs (I presume the same kind you get in the bathroom ceiling heaters you mentioned) instead of the simple coiled element you get in a $10 fan heater is nonsense. It would make a difference if the light bulbs were pointing at you - instant warmth on the side of you facing the bulbs, at the price of a lot of glare - but since they're just pointing at some heat exchanger doodad inside the heater, over which a fan moves air, the end result will be exactly the same as that of any other fan heater, except presumably with a bit of a jolly glow coming out of the exhaust slot.

(The kind of heat lamp you see keeping reptiles and birds warm, that has a deep red glow, looks that way because there's a red filter over the lamp. Heat lamps really are basically just big bright light bulbs; they run at a relatively low temperature by light bulb standards, but without a filter 375 watts of heat lamp is still good for easily as much visible light output as a regular 200W bulb.)

If the diagram on the "how it works" page is accurate, the Portable Furnace's 1500 watt power rating and four bulbs means this thing does indeed have four 375W heat lamps inside it, just like a normal bathroom light-heat-and-fan combo package here in 230-volt Australia. Those lamps have a pretty long lifespan, but I'd be surprised if they lasted any longer than an ordinary cheap fan heater. Hence, I suppose, the availability of replacement Portable Furnace lamp sets (for a mere eighty bucks - which is easily twice what they ought to cost...).

The advantage of resistive electric heat is that you can have exactly as much heat as you need, exactly when you need it, from a dirt cheap heater. No other technology can give you that two minutes of heat while you're towelling off after your shower. And if you really do need to heat only one room, a central heating system with a furnace will waste considerable heat even if you remember to close the vents in all of the other rooms.

But resistive electrical heating is still more expensive per unit of heat than all of the other technologies. It's a lousy solution for long-term applications. And the "dirt cheap heater" advantage kind of goes away, too, if someone suckers you into paying six hundred freakin' dollars for a fan heater. Sheesh.

If gas or other combustion heating is out of the question, consider reverse-cycle air conditioning. That's much more efficient than resistive heating, because it uses some electricity to pump heat from one place to another, and adds its own waste heat. The result is at least two times, maybe 2.5 times, as much heat output as electricity input. The only big disadvantage is that if the cold side of a normal air conditioner is cooled close to freezing, it won't be able to pump any more heat from it - so reverse-cycle works well for heating in relatively temperate climates, but is no good if a real winter has set in.

Air-con's also not cheap to buy - you certainly can get a basic reverse-cycle window air conditioner for the price of a Portable Furnace, but that ain't saying much. And even a window air conditioner is not entirely trivial to install. Portable air conditioners need a certain amount of "installation" too (cumbersome hoses...), and they have lousy efficiency. And all air conditioning is kind of goofy unless you intend to use it at least occasionally for cooling as well.

Cheap air conditioners also all still use the old "binary" control system; they're either pumping heat at full power, or not pumping any heat at all. You have to pay extra to get an "inverter" system that's able to run at fractional powers, which is often what you actually want rather than endless noisy thermostat-driven cycles.

The very best electrical heating, though, is the kind you get as a side-effect of something else that you'd be doing anyway.

If your TV consumes 100 watts while it's on, you get 100 watts of heat out of it, "for free". The same goes for every other electrical appliance in the house, definitely including computers. This is bad if you're paying to cool your house (or room full of servers...), but it's great if you're paying to heat it.

So if you're to the point where you're considering resistive electrical heating anyway, think about more entertaining things you can get that electricity to do on the way to warming the room. Even if all you do is abolish all traces of Seasonal Affective Disorder by lighting your living room with two $25 500-watt halogen shop floods pointed at the ceiling, that still beats the hell out of being suckered into paying $600 for a lousy fan heater!

The surprisingly expensive Amish fan heater

Via Consumerist, I found this rather cheeky ad.

Amish fan heater

Click for the whole thing, including reams of text. The Consumerist version of the same image is here.

You can buy one of these "Heat Surge" fireplace-shaped heaters for a mere $US587 (plus extra for optional, but included by default, remote control and extended warranty!) from their main Web site. But if you plough through the advertorial and call before the "order deadline" and do whatever else they say you have to do to get your special claim code and then enter it on this other site, you can get a heater with its special allegedly-made-by-real-Plain-Folk mantel for "just two hundred ninety-eight dollars"!

The Consumerist's ridicule centred around the Photoshoppery visible in all of the images - particularly amusing given the touted Amish connection - and the fact that this "advertorial" is disguised as a real USA Today article.

I concur with their derision. The images, in particular, remind me of the quickie that'll-do pictures you see illustrating Onion articles - not least because The Onion uses much the same layout as USA Today (or possibly vice versa).

But I was also intrigued by the claim that this "work of engineering genius from the China coast" could in some way save you money.

The heater has a quoted "5119 BTU's" (sic) of output. The British Thermal Unit is a measure of energy; BTU ratings for heaters are actually BTU per hour. 5119 BTU is 5,400,831 joules, a joule is a watt-second, 5,400,831 watt-seconds in one hour is almost precisely 1500 watt-hours per hour.

So this thing is a 1500 watt fan heater, with what looks like a less than totally convincing fake-fire effect.

I'm guessing 1500 watts of heater element, plus maybe 50 watts for the fan and lights.

And it "uses less energy than it takes to run a coffee maker"!

Well, if your coffee maker draws more than 1500 watts, then yes. Small domestic "Mr Coffee"-type machines actually usually consume something like 900 to 1200 watts.

And your coffee machine doesn't run at full blast all day.

The vendors of this highly decorated fan heater enjoin you to "leave it on day and night" - which actually isn't a very safe idea for most fan heaters, but let's give them the benefit of the doubt and presume that this big chunky heater won't set the curtains, or itself, on fire if left unattended. If you do run it all day and night, though, then if you're paying ten cents per kilowatt-hour for electricity, it'll cost you three bucks sixty a day to run it.

Over a three-month winter, you'd pay about $US330.

To be fair, the "Saves Money" page of the Heat Surge site clearly tells you how much power the heater consumes (only 750 watts, on "Medium"!), and that it'll cost "about 12 cents an hour" to run at full power, at a presumed eight cents per kilowatt-hour, which isn't much lower than the US average. And their advice about only heating the rooms you're using is sensible enough. But, you know, duh.

This heater would be even cheaper to run, and much easier to move from room to room (a major selling point!) if it didn't have the silly mantelpiece and lit-up fake fire.

And wouldn't you know it - those technological geniuses "from the China coast" have just in the last fifty years or so invented amazing "fan heater" gadgets. You'll be astonished to learn that these devices are much more portable than this large and cumbersome fireplace-shaped device. And they can be purchased at any discount store for, oh, approximately nothing!

Which'll save you enough money to run one all winter.

GreenPower funny numbers

The bunch of shady individuals who resell electricity to us (no, not these dudes - "Jackgreen", who're no better if you ask me) saw fit today to provide us with a cheery note telling us that, as of next year, we will automatically be supplied with "10% accredited" GreenPower!

GreenPower is, according to the Australian Government Web site all about it, new renewable energy. Not just the hydro-electric power that Australia's had since the Seventies; an actual replacement for the vast amounts of almost entirely coal-fired electricity (some of it the particularly filthy brown-coal-fired type...) that keeps the rest of Australia's lights on.

We have, Jackgreen excitedly added, the option of upgrading to 25%, 50% or one hundred per cent "accredited" GreenPower, for an extra fee, if we like.

Gee! Doesn't that sound great!

The GreenPower Accreditation program has actually been around for more than ten years now, as I discovered when I read the absolutely riveting 2006 GreenPower Annual Compliance Audit (PDF).

I felt obliged to plunge into this sizeable document because, on the face of it, the GreenPower numbers didn't seem to add up.

And the more I learned, the more confusing it became.

The thing that originally puzzled me is that the 25, 50 and 100% GreenPower rates from Jackgreen will cost us $AU1.10, $AU2.20 and $AU4.40 a week, respectively.

That's it.

A flat rate.

Whether your house's total electricity budget comprises two night-lights and a transistor radio, or five thousand marijuana plants thriving under fifty kilowatts of metal halide illumination, you pay a flat rate extra to have all of your electricity "greened".

I know it's a flat rate just by looking at the Jackgreen page that lists all three GreenPower options. The Product Disclosure Statement (PDF) makes perfectly clear that the actual tariffs for each level of GreenPower, not counting the extra weekly fee, are exactly the same!

(I also particularly like the significant "Daily Availability Payments" that apply across the board. Here in Katoomba there's about one brief blackout a week, and at least one longer one a month. "Why, when that happens they must refund the Availability Payment for the affected day," I hear you say! Alas, no.)

The Compliance Audit document tells me that GreenPower can be sold by the kilowatt-hour like normal electricity, or bought to match the amount of electricity you're drawing from some other supplier that (presumably) doesn't subscribe to the GreenPower scheme, or sold as a "consumption based product whereby customers nominate the level of GreenPower purchased according to a nominated percentage of their total electricity consumption".

That last one would appear to be what the schemes we're being offered are. But we're obviously not, in any economically meaningful way, "purchasing" a nominated percentage of GreenPower if we don't pay more, to account for that more-expensively-generated percentage, when we consume more bloody power.

This seems to be the most obvious thing in the world to me, but it nonetheless appears to have sailed right past the Government, who say on the GreenPower site that "you can buy 100% GreenPower for approximately $5.50 extra per week".

Except no you bloody can't, unless you just arbitrarily define "GreenPower" as "NotActuallyGreenInAnyWayPower".

Which, more rooting around in the document eventually made clear to me, seems to be what they've done.

Working my way on through the Compliance Audit, I hit the all-important Rules of the Program, which say that GreenPower providers must "source all generation included in a GreenPower product from GreenPower approved sources" and, as of half way through 2006, "source 100 per cent of accredited GreenPower sales from 'new' GreenPower generation". "New" is defined to mean "any generator built or commissioned after 1 January 1997 that is GreenPower approved".

This is, therefore, pretty straightforward. When you buy 100% GreenPower, you really do have to get 100% GreenPower, not as much GreenPower as your electricity dealer has to sell you, followed by ordinary, um, BrownPower. It doesn't mean that someone's going to send special green electrons to your house from a generator powered by kitten purrs, but if you order 100% GreenPower, however much power you draw really and truly should be sent into the grid, somewhere, by a new and shiny renewable source of some description.

But now we strike a problem.

Apparently nearly eight per cent of Australia's electricity comes from renewable sources at the moment, but that's including the old Snowy Mountain hydroelectric system, whose peak capacity is the thick end of four gigawatts but which doesn't run at anything like full capacity most of the time.

Take the Snowy system out of the picture - which you should for GreenPower calculations, since the rules forbid GreenPower providers to just sell that hydroelectric power - and you've got a magnificent 1.5% of our total consumption left over.

That is, at the very most, the sum total achievement of ten freakin' years of this GreenPower initiative. And a significant portion of the 1.5% doesn't qualify as GreenPower anyway, as we'll see in a moment.

At this rate, we might make it to 50% renewable energy in as little as three hundred years!

But right now, it's obvious that if any significant number of people sign up for any significant amount of GreenPower, the amount of genuine two-words-no-capital-letters green power available will be exhausted rapidly.

This was the point where the light dawned upon me, and I theorised that the government must have just shifted the goalposts and, themselves, allowed "GreenPower approved" generators to include a whole lot of... other... sources of electricity.

I was led to believe that there was some straightforward old fashioned lyin' coming up by the delightful discovery in section 2.1.4 of the 2006 Compliance Audit that "GreenPower providers are required to reduce emissions ... to 5 per cent below 1990 per capita emission levels, equivalent to 7.27 tonnes per capita by 2007" (emphasis mine).

Well, here we are at the end of 2007, and Australia as a whole hasn't quite done that.

What Australia's actually done - and yes, we should be very proud - is top the world in per capita power generation carbon emissions, with a magnificent 226 million tons emitted this year, about 10.7 tonnes per capita.

This is hardly surprising, since Australia is as crazy for air conditioning and plasma TVs as the USA (who are currently managing a mere 9.2 or so tons per capita), but we don't have any nuclear power at all.

Now, GreenPower's approved providers presumably do emit relatively little carbon per customer. But since there isn't nearly enough genuinely green power to sell to customers - as we'll see - I wouldn't be at all surprised if the actual per capita electricity-related CO2 output of GreenPower customers was only a hair below the national average. There's no way it's actually lower than 1990 levels.

So I was thinking that if they don't mind about that particular huge miss, they wouldn't mind a similarly bold declaration that GreenPower and BlackPower could be the same thing... from a certain point of view.

But in section 2.1.5, they define a "green" electricity generator as "an electricity generator that results in a greenhouse gas emission reduction and net environmental benefits; is based primarily on a renewable energy resource; and complies with the guidelines in the National GreenPower Program Accreditation Document".

Which would appear to rule out the source of 93-odd per cent of Australia's power. You just can't use that definition and simultaneously allow GreenPower purchasers to actually be sent regular power.

Flick on through to section 2.4, and you find that total GreenPower sales for 2006 add up to 802,417 megawatt-hours.

That sounds like a lot. And it is - you'd have to run a thousand-horsepower engine for 123 years to make that much energy.

But Australia's total electricity consumption is up around 200,000 gigawatt-hours per year.

So total GreenPower sales for 2006 were about 0.4% of Australia's total electricity budget.

Or one two hundred and fiftieth, if you prefer.

The Compliance Audit says there were 391,403 customers - 373925 residential, 17478 commercial. If you assume they're all on 100% GreenPower and they all get an equal share of the available power, that's a grand total of 2.15 megawatt-hours per customer per year.

This actually distorts the situation - a graph in section 2.6 of the Compliance Audit makes clear that sales to commercial customers were far higher per customer, as you'd expect. But let's run with the straight average for a moment.

An average US or Australian household is likely to consume around eight to twelve megawatt-hours per year. So the total current GreenPower sales are only enough to supply the current customer base for, oh, two or three months of the year they've paid for.

This is reflected in the fact that section 2.4, before it tells you that 802,417MWh of GreenPower were sold in 2006, tells you that 3,889,200MWh of GreenPower were purchased.

This threw me for something of a loop. I've read over it several times. I'm doing my best to figure out what it means. If anybody knows better, do please fill me in (or just post a comment below).

The sold/purchased discrepancy is an unusual situation. Not often do the books of a business - well, of an honest business, anyway - tell you that 4.8 times as many Acme Widgets were purchased by customers as were sold by Acme.

But here in the world of GreenPower, "product providers" certainly can buy way more power than they actually sell.

There's some sort of certificate system involved too, but it's not related to any actual consumer reality, because of that weird connected-to-nothing tiny flat rate I mentioned way up at the top of this post. I presume there are government subsidies involved as well - so, in the end, everybody's paying for this scheme whether they pay the flat fee or not - but fat chance of finding any mention of those on the GreenPower Web site.

Aaaaaanyway, the factor-of-4.8 difference between GreenPower purchased and GreenPower sold quite neatly increases the 2.15 megawatt-hours per customer to about 10.4MWh. That lines up much better with a plausible figure for actual average demand from all of those GreenPower "users". If everybody was on a 100% GreenPower contract then it'd be too low to account for the electricity-hungry commercial customers, but I'm sure there are lots of 25% and 50% contracts in there pulling down the average order size.

So it seems to me that this really is the deal. The government goes through all of this rigmarole of officially approving GreenPower suppliers, tra la, and allows customers to sign up for the suspiciously-cheap "100% GreenPower" and receive faithful assurances that this means their electricity supplier is "purchasing" exactly as much GreenPower as the customer uses.

And then in their official audit report they just whiz right over the trivial detail that 79% of the item being purchased does not, if you want to be boringly picky about it, exist.

And then in section 2.7, you can hear them giggling as they give every single GreenPower provider the maximum five-star rating for honesty in every kind of marketing they conduct!

Awesome marketing rating

Step right up, folks! Everyone wins a prize!

Any new GreenPower drive that causes market growth to exceed the growth of the actual GreenPower generation capacity will, of course, only make the ratio of power purchased to power sold even worse. And it's not as if all of those extra customers will be bringing billions of dollars with them that'll make GreenPower more real than it currently is. Each new customer, wanting ten-odd megawatt-hours of environmentally friendly power a year, will be (directly) paying at most $AU286 to help make that happen.

You could realistically expect a big old 1.5-megawatt wind turbine to be able to produce about 4000 megawatt-hours of power per year. It'd be more than 13,000MWh if the thing ran at full power all the time, but the capacity factor of wind generators - the fraction of the time, on average, that they can operate at their rated power - is lousy, down around 30%.

But 4000MWh in a year, ignoring storage and distribution, is still enough to run 400 ten-megawatt-hour-per-year households.

If all you're getting from those households is 400 times $AU286 per year, though - $AU114,400 - it'll be a bit of a while before you can afford that turbine. A 1.5MW turbine will set you back at least a couple of million US dollars, and its upkeep ain't free either.

So, if the extra GreenPower rate is all you have to spend, it'll be twenty years before you can even buy that one darn turbine. And then it's probably going to wear out in thirty years, tops - whereupon, given what you paid to run it in the meantime, you may just about be able to afford a replacement. Whoopee.

Page 3-2 of the Compliance Audit finally dropped a tantalising hint about what is to be done if "there is a shortfall of valid claims for new GreenPower purchases to satisfy new generation requirements for sales of a GreenPower product", and directed me to the even more fascinating National GreenPower Accreditation Program Accreditation Document (PDF).

Therein, I found the straight-faced statement that purchases and sales are required, as they would be in a sane system, to be equalised after some reasonable period of time.

In the staggering situation that this turns out to be impossible - as, I'm willing to bet, it has been for pretty much the entire existence of the GreenPower program - GreenPower Providers are directed to make up the difference with non-"new" GreenPower sources (of which there are nowhere near enough), and are then allowed a five per cent "shortfall" on energy sales (still not nearly enough to fill the gap), and are then directed to "rectify the shortfall via credits/rebates to affected GreenPower Customers".

And if they don't do that, they can have their oh-so-precious GreenPower accreditation revoked.

I can find no evidence that any credits or rebates have ever been given to anyone, or that any GreenPower providers have been taken to task about it. Since their job is self-evidently impossible, I suppose it'd be a bit unfair to make them give back the money that's supposed, however feebly, to be priming the renewable energy pump. But this still seems to make an absolute nonsense of all these po-faced rules by which everybody says they're abiding.

As it stands, the GreenPower system seems to me to be a facade. At a glance, it looks great - but if you pay a bit more attention, the green-ness turns out to be only skin deep.

I suppose we should be grateful that there are at least (apparently) honest numbers in the public documents, and it's not all a total cover-up. But that doesn't excuse the fact that the whole scheme is basically a sham. And it certainly doesn't make it OK for a genuinely progressive environmentalist political party like The Greens to just go along with the pretense, using GreenPower as a political playing card along with all of the other issues-that-mean-the-opposite-of-what-they-seem-to.

I can't help feeling that I must have missed something very serious, here. But it's not just a couple of numbers in the Compliance Audit that touched this all off - it's the small flat rate, the well-known lack of any serious new renewable energy generation capacity in the country, and the glib insistence from all of the electricity resellers that you can just tick the box, pay the few bucks a week, and be carbon-neutral just like that.

Has anybody else noticed this? Is there something more to it that I've failed to understand?

Humankind's Endless Quest for a Substitute Plugpack

I've been asked variations of this question often enough that I thought I'd give it its very own blog post. I hope it's suitably grateful.

I have a Canon Powershot A95, a wonderful little digicam - smart enough that I can take decent pictures with it, cheap enough that I can afford it, small enough I can carry it everywhere. Moreover, I just found out I can actually remote-control it with gphoto2. Huge vistas of time-lapse photography opened up before me. Only, it's hard to take a 7-hour time-lapse on one set of AAs.

Canon sells the "ACK600", an AC power adapter rated at 4.3 VDC and 1.5 A; but they sell it for $50.

On the other hand, just around the corner is a junk shop with a big cardboard box full of wall warts that have become separated from their widgets. Last time I went the guy sold me 5 for $4. Am I safe (assuming I get the polarity right) feeding my camera from a wall-wart rated at 4.3 VDC and 1.5 A? Or is the ACK600 especially well-regulated or something? Is the ACK600 likely to be supplying 4.3 VDC exactly, or something higher? Am I going to damage my camera if I feed it 4.3 VDC from my lab power supply?

Anne

I would not be surprised if none of the plugpacks in the junk shop's box are suitable for powering your camera. But it shouldn't be difficult to power the camera from some other plugpack.

(Note: This is another of my famous "all care, no responsibility" answers. No smoking wrecks which once were cameras will be replaced by the management.)

The great danger of old plugpacks is that they may be unregulated. A regulated power supply will (to a first approximation) always output its rated voltage(s). This means it's fine to plug a big "12V 10A regulated" power supply into a little "12V 75mA" device; a regulated power supply may behave oddly if it's extremely lightly loaded, but that's very seldom a problem.

An unregulated plugpack, on the other hand, will only output its rated voltage when it's fully loaded. If it's completely unloaded, it'll deliver precisely root-two (1.414...) times its rated voltage.

If an old heavyweight linear plugpack (as opposed to the modern lightweight switchmode type, which are almost always regulated and usually accept a range of input mains voltages) isn't specifically labelled "REGULATED", you should assume that it isn't.

(The other trap waiting for you in the old-plugpack box, apart from breaking out the multimeter to make sure which output wire is the positive, is power supplies that have no positive output wire. Some plugpacks output alternating current, instead of the direct current that most small devices expect. An AC power supply for an old modem or something may have voltage and current specs that look fine, but if you plug it into a DC-expecting device and that device doesn't have rather robust reverse-polarity protection, a small noise and a funny smell will soon occur.)

It's reasonable to assume that most gadgets will accept their rated input voltage plus or minus ten per cent, but lightly loaded unregulated power supplies can easily be outputting more than 1.3 times their rated voltage. That can blow stuff up.

It's good that input a bit above or below the rated input voltage for a given device is generally fine, because the official power supplies for some devices have weird voltages. Yours is one such; "4.3VDC" is an oddball voltage that you're almost certain to be unable to find an a box o' power supplies. Your camera will probably run perfectly well from a 4.5V regulated plugpack, though, as long as that plugpack can deliver enough current. 1.5 amps is a bit on the high side (and the camera won't need it most of the time - only charging the flash is likely to push it above an amp), but current ratings that high are easy enough to find in off-brand switchmode plugpacks from electronics stores these days.

And yes, a bench power supply set to the same voltage and with enough current capacity will also power your camera just fine. This sort of setup, with an inline ammeter (don't trust the current meter on an inexpensive bench supply for more than approximate readings), can make it easy to figure out exactly what the acceptable voltage range for a given device is.

The camera may, for instance, still work but with obviously slower zoom speed at 3.7V, and it may not draw any more current (or actually draw less) at 4.8V than at 4.3V. In that case, you know you're pretty safe with the higher voltage. If a device starts drawing more current as you raise its input voltage, it's a good idea to stop raising the input voltage.

Even without such investigations, I'd be very surprised if you couldn't also rig up an old-style external battery pack wired to an appropriate DC input plug. Three alkaline D cells in a holder (for 4.5V nominal, and something in the order of 12 amp-hours of capacity even at a constant half-amp drain!) would probably be fine, and give you impressive run time. I'm also about 90% sure that four 1.2V NiMH cells in series (for 4.8V nominal) would be fine, even though they'd be rather more than 1.2V per cell when freshly charged.

Getting back to old plugpacks: The final problem with them is that they can be dangerous.

Plugpacks have been built down to a price for many years, and it's common to find a gadget that's passed lots of electrical safety tests being powered by a very dodgy plugpack indeed. It's not easy for a gadget importer to change the power supplies in devices that take mains input, but it's very simple to get a device safety-certified with a top-quality plugpack, then increase profits by putting ten-cent assembled-by-peasants plugpacks in with the actual retail gadgets.

A sensible design for a plugpack should include some kind of overcurrent and overheating protection. Some have simple fuses, but those are difficult to replace if they pop; a self-resetting overcurrent and thermal circuit breaker is much better.

Those sorts of things cost the manufacturers, oh, maybe even a dollar each, though. So it's perfectly normal to find linear plugpacks, old and new, that have no emergency cut-out features at all.

I remember one line of cheap multi-voltage one-amp plugpacks of which I bought a few on Super Clearance Special, years ago.

I ended up having to carry two of those plugpacks out into the garden, dangling them gingerly by the cable as the smoking interior made noises reminiscent of an angry rat.

The vast majority of plugpacks, even ancient ones with appallingly poor efficiency, will behave themselves perfectly well pretty much forever. If they die, they die harmlessly, with an open-circuit transformer or something.

But it's still not a bad idea, whenever you plug in an AC adapter, to think about what might happen if that plugpack decided to catch fire while you were out of the house.

If it's plugged into a powerboard that's sitting on your wool carpet: Not so bad.

If it's between a pile of old clothes and a box of tissues: Consider a change.