Kickstarter: muppet graveyard part 2

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!

[IMAGE REDACTED FOR LAWSUIT THREAT]

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

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

It seems tantalizingly close, right? But it’s not. 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.