Locklin on science

Kickstarter: muppet graveyard part 2

Posted in fraud, investments by Scott Locklin on March 1, 2013

Perhaps people think I engage in hyperbole about Kickstarter projects. No, I merely speak the obvious truth. It is a place of fraud and deception, a place which takes advantage of well meaning nerds who don’t think critically. Remember my five criteria for a perfect Kickstarter marketing pitch? Let’s review.

  1. Make it hardware related. Most internet dorks know nothing about hardware and are acutely aware of  and embarrassed by their lack of interaction with the real world. This is how stupid  ideas like solid printing get traction. Keyboard warriors want to work in meatspace, but they don’t know how. For a small donation, they can be hardware hackers!
  2. Make it “open source.” Keyboard muppets luuuurve open source, as it gives them “free” toys to play with. It doesn’t matter if it costs money, it doesn’t matter if it actually functions; what matters is that it is freeeeeeee.
  3. Make it related to their nerd-dildo (aka their “smart phone”). Modern techno-muppets have a relationship with their nerd-dildo not unlike that between Gollum and his precious. Polishing the nerd dildo and giving it even more power … tapping into the love affair between a nerd and his dildo strikes powerful emotional chords.
  4. Make noises about a super great prototype which will be distributed via junky open source rep-rap solid printing.
  5. Make it related to some fashionable moral crusade. If this were a mere gadget, only the most devoted Gollum would care, but keyboard warriors are going to save the goddamned planet with their open-source nerd dildo!

My next example embodies at least three of the five points. It is a piece of hardware. It is supposed to power an iphone. And it is supposed to save the environment. What is it? A Stirling engine which powers an iphone using the energy from a coffee cup. Behold, the Epiphany onE Puck!


Quote from kickstarter site:

The idea behind the Epiphany onE Puck is to use a stirling engine powered solely by heat disparities, such as a hot or cold drink, a candle, ice, etc. These heat sources will provide enough power to the stirling engine to fully charge your cell phone battery. There’s nothing new about Stirling engines – they were invented in the early 1800s – but thanks to modern materials and modern electronics, we are able to put them to use in ways that weren’t previously possible.

So, now the new question is, How can a small device that powers my cell phone change the world?

Well, the fact of the matter is, it won’t change the world. It also explicitly violates the laws of thermodynamics, so it won’t do anything but line the pockets of the people pitching it. How do I know this? Well, several ways.

The first way is common sense. It’s obvious this won’t work if you have ever looked at a small gamma Stirling engine like this one. There used to be a home made coffee machine powered gamma Stirling in the lab. It was made by a skilled machinist who built scientific apparatus every damn day, and it made just enough mechanical energy to overcome friction and turn over; and this from a very hot coffee machine. There are others that actually do work on just a coffee cup; they don’t produce much more useful work than is required to overcome friction either. Small home made Stirlings are fragile things that end up using graphite pistons to overcome friction; it is a big achievement to make a little one that turns over at all. Check the model engine builder groups if you don’t believe me.

The second way is knowing about practical Stirling engines that do useful work. The ones that are actually efficient use complex mechanical tricks to extract as much energy as possible. One of the main necessities is for a better working fluid than air; so you end up with lots of pressurized seals and such, to keep in compressed helium or whatever they use. The very best ones are completely sealed and connect to the dynamo via magnet. They also require extremely efficient regenerators; this one pretty obviously has no regenerator. The efficient ones are always much larger than a coffee cup, to fit all the necessary mechanical junk in it. The model shown in the pitch is a toy gamma Stirling with none of these advanced features. One that never actually functions on video, mind you: an LED lighting up doesn’t impress me. Therefore, they fail at this project on inspection. I once had an idea to cool a beer can with a hand made, hand powered reverse Stirling cycle cooler. It can theoretically be done, but the design so far is intensely complex. Having gone through this exercise, I know they didn’t by looking at their proposal. Example from history: Philips spent decades making a 200 watt Stirling engine which, well, go look at it. It is hugely complex, and ultimately failed because it was too costly to manufacture.

The third way is to do math. How much energy is needed to charge a cell phone? Batteries in them hold 1200mAH at 3.7 volts, for 4800mWH. They use around 60mW when they’re suspended, which is why you need to keep your dumb phone hooked up to a charger all the time. But anyway, is there 4-watt-hours in a cup of coffee? That’s 4 times 860 calories, or 3440 calories. A calorie is conveniently the amount of energy required to raise 1 gram of water by 1 degree C. So, their 6 ounce coffee mug or 177 grams, at a generously hot 70 degrees C with generously cool 20 degrees in your room yields 12390 calories. So, all we have to do is get out a quarter of the energy in a hot cup of coffee to do this! I’m all excited. OK, how? Stirling engines? Let’s forget about all the practicalities of designing one, and just use the most theoretically efficient heat engine: the Carnot cycle. The efficiency of a carnot cycle is

efficiency = 1 - \frac{T_c}{T_h}

T_h and T_c must be in absolute temperature, Kelvin. So, what is the maximum possible efficiency of a heat engine at these temperature differentials?

efficiency = 1 - \frac{273+20}{273+70} = 0.15

It seems tantalizingly close, right? But it’s not. T_h is an exponentially decaying function of time, even without assuming the Stirling engine sucks energy into it. Integrating over time (an exercise for the reader; that’s enough LaTeX for you), you get an average efficiency number closer to 0.08. Only 1000 calories of mechanical energy can be retrieved even in principle from a coffee cup heat source. That’s assuming Carnot perfection. Real Stirling engines, using the maximum of tuning and technical innovations achieve 0.5 times Carnot on the heat pumped into them. Now we’re down to 0.04, or 500 calories. This is leaving out the fact that the design they are using is at best 5% Carnot; probably significantly less than 1%. What’s left in our calculation? Oh, actually, a Stirling engine can’t magically suck all the heat out of a coffee cup: most if it is radiated to the world. Call that a generous 10%. 50 calories left! What is that in mWH? 0.05. Less than the phone uses at idle. Adding back in friction, dynamo inefficiencies and real world gamma Stirling efficiency, the real result is pretty much zero.

There is a small chance I’m wrong about this one. Maybe they have some very innovative technique which actually can extract significant energy from a coffee cup. Should they make one that does something more than light up an LED, I will apologize profusely for saying nasty things. But it sure fails the sniff test from where I am standing.

Why do I bother? I hate it when people are paid for stupid technological shit. It robs the credulous and makes people who do real things look bad. Stirling engines are cool; I hope serious people continue to work on them. I just wish muppets would leave them alone. If you want a real Stirling engine, send money to the guys at Sunpower. They’re actual experts who can get shit done.

22 Responses

Subscribe to comments with RSS.

  1. Jim said, on March 1, 2013 at 10:16 pm

    I just like the shirts. Makes it look like you’re advertising “E”, (i.e. ecstasy/mdma)

  2. EddieM said, on March 1, 2013 at 11:19 pm

    All of that also assumes that you don’t drink any of the coffee!

    • Scott Locklin said, on March 2, 2013 at 8:28 am

      And that coffee doesn’t take any energy to make!

  3. Anomaly UK said, on March 2, 2013 at 8:50 am

    Last and not least, if this were to actually work, wouldn’t it cause your coffee to cool down faster than otherwise?

    • Scott Locklin said, on March 2, 2013 at 9:16 am

      It certainly would if it sucked up 100% of the energy available in a cup of coffee! There is a reason coffee mugs are made of non-conductive material instead of aluminum or copper!

  4. Alexey said, on March 2, 2013 at 7:36 pm

    Just first link in Google “semiconductor heat to energy”

    Also we can just try to use thermocouple. Though power will be rather low.

    • Scott Locklin said, on March 5, 2013 at 5:18 am

      In principle this could work, though in practice, I am highly skeptical as to its efficiency. Visible light is much higher in energy, making the resulting electrons more usable, and solar panels are not so efficient. Hard to tell what’s going on with the small information on the link.
      I also think any working scientist who uses the word “nano” should be taken before a board of enquiry, but I appear to be unique in that regard.

  5. neutrino_cannon said, on March 3, 2013 at 7:16 am

    “This is leaving out the fact that the design they are using is at best 5% Carnot; probably significantly less than 1%.”

    Yikes. At that point, ditch the moving parts and use a thermoelectric generator!

    It would be very retro:



    A human body is shedding about 96 watts of metabolic waste heat. A good thermocouple is what, half a percent efficient at that sort of temperature differential? So that’s 500 mW, assuming that you could make some sort of mylar burqa with bi-metallic heat radiator fins that covers nearly all the skin.

    (Actually, now that I think of it, wouldn’t a lot of that heat be in exhaled breath?)

    With a slightly more fashionable cut of clothing and a few generations more power efficient nerd dildos, it might be practical to have a body-heat powered trickle charger.

    For people who live in Alaska.

    • Scott Locklin said, on March 3, 2013 at 8:55 am

      I’ve been looking for that photo for *years* -thanks for finding it for me! I don’t remember if I’ve mentioned it on here recently, but that old Russian lantern stuck in my mind from a very young age.
      In principle a well designed Stirling engine can beat the known Seebeck effect for efficiency. One of the projects of the company I liked (Sunpower, not these kickstarter guys) is to make Stirlings to replace the Seebeck thermocouples in deep space plutonium heat batteries. Then again, maybe research in high Tc superconductors will come up with something with lots of phonon drag at room temperature. Naaaah.

  6. Justin said, on March 6, 2013 at 8:10 am

    I received the same letter today. Will you contact me outside the comments?

  7. Ali G said, on March 8, 2013 at 6:47 pm

    “There is a small chance I’m wrong about this one. Maybe they have some very innovative technique which actually can extract significant energy from a coffee cup.”

    it’s worth mentioning that Carnot cycle in fact is the most efficient way to extract energy from two heat reservoirs. Any more efficient technology would violate the 2nd law of thermodynamics.
    The easiest way to see this is to note that the Carnot cycle is reversible: it can run both as a work extractor and as a heat pump. Then if we have a more efficient way to extract work from two reservoirs, we can connect such a machinery to a reverse Carnot cycle machinery and transfer energy from colder reservoir to hotter for free hence decreasing the entropy and violating the 2nd law of thermodynamics.

    • Scott Locklin said, on March 8, 2013 at 8:30 pm

      Yep; this is worth remembering and saying explicitly. Thanks for pointing it out.

  8. Dusty Yeti said, on March 13, 2013 at 7:53 am

    Wow! Did you see that?! The thermal energy transfer from that thick ceramic cup of coffee can generate a 5v charge of sufficient current to charge the phone! Just by sitting on the onE PUCK! Just by sitting on it. Just place it there, on that magical puck. A few seconds is all it takes. It’ll suck the heat RIGHT out of your coffee.

    …The funny thing is, I did some calcs to estimating how much energy is in that coffee, and then I realized you probably did that already, and looked back at your comments to see that YES! We’re in the same ballpark. They have to suck an awful lot of energy out of that coffee and then get the Magical Duck Puck to capture it all….just from sitting there! It’s magic, I tell ya.

    Now the coffee is cold. I guess I’ll put in the 2000 WATT microwave over here for one minute and get it back to drinking temperature.


    • Scott Locklin said, on March 13, 2013 at 8:22 am

      There is truly no hope for humanity. Kickstarter funders are supposed to be the smart ones who can, like, use electronics.

      Did you look at the “grating spectrometer” that got funded as well? That’s even worse, and it got almost as much money. This one has a chance of turning over enough to light up an LED if they’re decent machinists, making it an amusing toy at least. The “spectrometer” just makes rainbow patterns on your iphone. Something you could have done without a $0.001 piece of paste board.

      Glad we came out with similar numbers; math checks are always a good thing.

  9. johndietl said, on April 13, 2013 at 1:32 am

    Nice deconstruction. If you search for the Epiphany onE Puck on google, you’ll find hundreds of sycophantic credulous articles praising this piece of junk. It’s a good reminder of how the self-styled ‘tech’ industry is full of ignorant twerps.

    Another Kickstarter kick to the groin: recently, I followed a link to this kickstarter project: http://www.kickstarter.com/projects/robocat/thermodo-the-tiny-thermometer-for-mobile-devices

    To my eyes, these guys seem to be selling a thermistor connected to a headphone jack, which costs approximately 10¢ in components and 5 minutes in design time. They plan to encase the thing in something that looks cool. Am I wrong to feel annoyed that they raised $300000 for this?

    Besides, isn’t this kinda stupid? Who needs a thermometer for your iPhone? Of course, they won’t say what the time constant of the thermometer is on the kickstarter page. So I am looking forward to thousands of nerds removing their phones from their pockets and holding them out for 5 minutes* expectantly waiting for the temperature to settle.

    It’s a thermometer, people!

    I haven’t commented here before, so I’d like to say I love this site, and keep up the great work.

    John Dietl

    *I did a back-of-the-envelope calculation estimating a time constant of 150-6000 seconds depending on the type of convection, assuming they encase the thermometer in aluminum.

    • Scott Locklin said, on April 13, 2013 at 8:15 pm

      Thanks. I’m not sure I want to thank you for pointing out the thermistor thing; that’s grotesque. Maybe I should hide my blog and sell some dumb “magnet hooked up to cell phone” thing on kickstarter…

      • Alan said, on October 5, 2014 at 12:43 pm

        Just found your site after browsing to see if anything had happened in the world of onepuck. I’m interested in stirling engines, soon as I saw mention of the onepuck I thought – “Oh yes?” and did the same calcs you did.

        But I quite like the plug-in sensor idea. (not its enormous fundraising, just the ability to power and control a small external device using existing connectors..). Combine it with a simple timer and you could turn an old phone into a datalogger for a couple of bucks…

  10. […] by Scott Locklin’s series of posts criticizing awful Kickstarter projects, I would like to share my thoughts on the […]

  11. russellmcmahon said, on November 30, 2013 at 10:47 am

    NAy update on this (late November 2013). They should have go to at least the “opps, sorry” stage by now.

  12. Darth Skeptic said, on March 17, 2014 at 4:32 pm

    You should check out the latest project “update”. And the comments that ensue.
    The backers are in open revolt.

    • Scott Locklin said, on March 18, 2014 at 12:01 am

      Beyond the fact that his gizmo obviously violates the laws of physics, the fact that he threatened to sue the guy who pointed this out ought to have said something about this clown’s business acumen and ethics.

      Too bad there are no shorts for kickstarter projects.

  13. Atalanta said, on May 28, 2014 at 6:45 pm

    Like your blog, wish I had seen it a year ago 😉 The suit letter you posted, made me wonder if the person who wrote it learned Engrish off a serial box. LOL I will have to read more of your posts. Hasn’t turned me off Kickstarter, with one exception, all the projects I’ve backed and been funded have been great (several I’ve purchased more after the project).

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

%d bloggers like this: