
Kickstarter project for $100 - 1 kW - stirling engine - meow
http://www.kickstarter.com/projects/672465444/low-cost-sterling-engine?ref=live
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ck2
Yes gas is near $4 - what does that have to do with utility prices, since
there aren't any gasoline powered plants in the USA since the 70s ?

I would have to assume the way the utility company produces power is far more
efficient than a town with thousands of mini-engines. Only stuff like solar
cells work better in distribution.

Not sure how this would work either - what fuel are you going to use to power
it for 24 hours without maintaining it? Will it drive an alternator to power
an inverter? How stable would the feed be?

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napierzaza
A huge amount of the generated electricity is lost on resistance of the power
lines on the way to your house. So having it in your basement and going 30
feet to a lamp/outlet would be more efficient.

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matthiasl
According to wikipedia, the average loss on the power lines is 7%. Source:

[https://en.wikipedia.org/wiki/Electric_power_transmission#Lo...](https://en.wikipedia.org/wiki/Electric_power_transmission#Losses)

That's not what I'd call "huge".

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jerfelix
Looks like a cool project.

One note to entrepreneurs using Kickstarter, or creating any slide
presentation for potential investors: Take the time to spell check your
slides.

Tim Sefton (creator of this project), if you happen to be reading this, here
are some notes that may help you make your presentation more professional...

"One thing.. The Sterling engine is about 10% more efficent then the gasoline
engine, but strugles with changes in suden acceleration - like what is needed
for cars."

If you are the author of the presentation, you may want to correct the four
errors: efficient, than, struggles, and sudden. Also misspelled is
"temperature" (on the previous slide),

Not a big deal to me, but some potential investors will absolutely be turned
off by that.

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colanderman
Not to mention it's "Stirling", and not "Sterling".

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GigabyteCoin
This. Maybe it's just because I am a web designer and lover of the English
language, but when a company's blog URL looks like this: <http://volodesigns-
sterlingproject.blogspot.com/>

a) free site b) a dash? c) mispelled stirling?

I get just a tad anxious.

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MichaelApproved
_"Well the average US household uses about 8,900KWH of electricity per year -
that comes down to 24 KWH per day and so our goal is to have a minimum engine
output of 1KW so that it can produce close to the average home use of
electrical power per day (24 hours of 1 KW output give you 24KWH)."_

This math isn't taking into account that the power use isn't consistent,
batteries will be needed to handle the variances in consumption. You'll never
get 100% efficiency from power storage so the amount needed per day is much
higher.

I also didn't see anything about the temperature required to make this run.
Does this go on a roof or do they expect me to keep this in the fireplace the
whole time.

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jws
_You'll never get 100% efficiency from power storage so the amount needed per
day is much higher._

Lead acid batteries are 85-95% efficient for getting power in and back out. It
doesn't change your sizing much.

That said, until a significant percentage of the utility's customers are using
these devices, it makes no sense to use batteries. Just sell surpluses to the
grid and buy back to handle peaks.

If you have no grid, then about $1000 of batteries will cover you, and need
replacing every 5-10 years. Either way, your inverter is probably around
$2000.

I'd have already clicked to buy in, except there is a missing chunk of the
efficiency. Assuming I don't have a small lava flow next to a stream in my
basement, what is the total projected efficiency of these units from fuel to
electrical energy? They don't seem to be addressing burner efficiency. How
will it compare to a small gasoline powered generator? (You can't buy a diesel
genset this small.)

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SwellJoe
_If you have no grid, then about $1000 of batteries will cover you, and need
replacing every 5-10 years._

This is wishful thinking, both on lifespan and cost of a household battery
bank sufficient to run average household appliances like air conditioning and
electric water heater and such. Even deep cycle batteries in this sort of
working environment will need replacing every 3-5 years (and past 3 years,
you'll probably be working with maybe half the capacity of what you started
with). The workload of a household running off of batteries during periods
when power usage far outstrips power generation is really hard on batteries.
There are very expensive batteries that are rated for 5 years or more of use,
but they cost two or three times what regular deep cycle lead acid batteries
cost, making the total cost much higher. You'll also need more than $1000
worth of batteries for an average American household that uses air
conditioning and electric heating devices.

I live in a motorhome with a $300 battery bank (a motorhome has far fewer
energy users than a standard home, and I don't run AC, microwave, or electric
heaters off of the batteries; I have to crank the generator to use those), and
solar on the roof. I'm very familiar with the limitations of batteries, and
lead acid battery technology is extremely unforgiving of discharging beyond
50% (even beyond 75% leads to degradation, but most people in RVs accept that
because the weight of carrying more batteries to be able to run at 75+% charge
at all times is more costly than replacing batteries more frequently).

But, I agree with you that selling back to the grid is the way to deal with
this problem in a home on the grid. It's more cost-effective and more
environmentally responsible.

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jgrahamc
It's possible to buy something like this.

A WhisperGen which generates electricity (1kW) and makes hot water using a
four-piston Stirling Engine:
<http://www.ehe.eu/ehe/dm/whispergen.asp?nombre=2401>

They do both because they get cooling by transfering the heat to the domestic
hot water supply getting hot water and electricity at the same time. They are
powered by natural gas. The gas company E.ON in the UK did a study on them
(they also provide them I believe):
<http://www.microchap.info/Carbon%20Trust%20field%20trial.pdf>

To quote that report: "For typical family homes, carbon savings of up to 20%
are realistically attainable with economic payback of around 3 years."

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colanderman
WhisperGen is also only available in Europe and costs two orders of magnitude
more than this device would last time I checked.

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JoeAltmaier
But this device is vaporware, and its price is a pipe dream.

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Volodesign
Lets hope not - we did complete a working prototype, proving out the
mechanics, linkages, and feasibility. We are pretty close to budget on the
full sized model - bearings may take us slightly over the $100 mark.

~~~
jgrahamc
What would be useful is an apples-to-apples comparison. The WhisperGen is
about £3,000 in the UK but that's a complete installable unit in the home that
burns natural gas and hooks up to the electricity and water supply.

It sounds like your $100 is for just the motion part of the engine (perhaps
I'm wrong about that). Do you have a sense for what it would cost me to go
from having nothing to a working system in my home generating electricity?

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ctdonath
Variant idea: a small portable version for camping. Stick one end in a fire,
USB plug for power connector at the other. 2.5W shouldn't be hard to get under
conditions where "unreliable" is normal.

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meow
It will be kind of heavy though. For simple charging of appliances, other
projects are very interesting:

[http://www.kickstarter.com/projects/ryochijiiwa/bootstrapsol...](http://www.kickstarter.com/projects/ryochijiiwa/bootstrapsolar-
portable-power-pack-kit?ref=live)

[http://www.kickstarter.com/projects/davefoster/lilypad-
using...](http://www.kickstarter.com/projects/davefoster/lilypad-using-light-
to-power-all-our-mobile-device?ref=live)

~~~
ctdonath
I have a solar charger/battery. Surprising how often you can't get enough sun
to matter, as you need many hours of continuous direct bright light to collect
anywhere close to enough.

I'm imagining a sort of pencil-sized Sterling; stick one end in the fire and
the other in a cup of cold water. Not reliant on ambient/weather conditions
for power.

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damoncali
I've got a miniature Stirling on my shelf. It's a two cylinder setup that runs
off of two small alcohol lamps (about the equivalent of two candles), and is
air cooled. It weighs about a pound (but could probably be lighter). I don't
know exactly how much power it puts out, but it's not much - you can stop the
flywheel with light finger pressure.

More heat would produce more power, but I think pencil sized may be a bit
optimistic. I like the idea though.

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colinsidoti
Although the goals are clearly different, Dean Kamen (inventor of Segway) has
been working on optimizing Stirling engines for years with seemingly great
results:

[http://www.nextenergynews.com/news1/next-energy-
news4.24.08d...](http://www.nextenergynews.com/news1/next-energy-
news4.24.08d.html)

~~~
meow
One particular design that I'm very interested in is a quasiturbine based
stirling engine. It seem to have a lot better power/volume ratio than other
stirling designs. Unfortunately, I haven't seen even a single running model
yet :(

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rcfox
What sort of performance could you expect by just sticking this in the wall of
your house? In the winter, you've got cold air outside and you're already
heating the inside. In summer, you've got hot air outside and you're cooling
the inside. Does it matter which side is hot/cold?

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grecy
I like that idea - can anyone commment further? Up here in the Yukon it's
regularly -30C and below for long stretches and we all have our wood stoves
burning 24x7 for 4+ months.... It would not be hard to have one end touching
the wood stove (200-400C) and the other end outside (-30C - -40C). Will this
work?

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meow
It depends on what your power requirement is. For a 200C difference, you
should be able to get around 500W to 600W with a properly built stirling
engine.

~~~
grecy
Sounds nice for all the people running off-grid up here who get so little
precious sunshine in the winter. Can you provide more information on where I
might be able to buy such a Sterling engine? Are there any companies actively
making them?

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Volodesign
Thats what we saw and why we started the project - just not enough solutions
for real world requirements. The engine itself is somewhat simple, its the
thermodynamics that are tricky - There are only a few moving parts, no spark
plugs, no oil, no valves and works off of any kind of heat.

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damoncali
An interesting side note: You can build one of these that will run off a
candle and fit in the palm of your hand. I've got one in my office. It's a
pretty neat technology.

~~~
grecy
Can you give us more details please - did you build it? buy it?

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damoncali
It was a kit like one of these:
[http://www.ministeam.com/acatalog/Bohm_Stirling_Engines_and_...](http://www.ministeam.com/acatalog/Bohm_Stirling_Engines_and_Kits.html)

I also tried to build one from scratch once, but only got a few parts in
before I sold my lathe and mill. The kit was much easier...

Also look up flame eater or vacuum engines. Pretty neat.

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eogas
>The second difference is the Stirling engine is more efficient then the
gasoline driven engine.

Gotta proofread this stuff.

Anyway, I was thinking recently about how a stirling engine could be powered
by solar energy, and discovered that this is actually done. From wikipedia:

>Placed at the focus of a parabolic mirror, a Stirling engine can convert
solar energy to electricity with an efficiency better than non-concentrated
photovoltaic cells, and comparable to Concentrated Photo Voltaics.

That's cool, and I'm startled that it isn't mentioned at all on this
kickstarter page, especially considering the first paragraph of the pitch.

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colanderman
Problem is, CPV only works with clear sun. i.e. it's best for deserts. My
hunch is this is targeted at off-grid homesteaders, who tend to live where
there's vegetation (and thus clouds).

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MrEnigma
Seems like a huge long shot. Even if you wanted to get one now, it's $250.

I guess I've never seen this yet, but what happens when they can't' deliver
you the working product? Do you get your money back?

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MrEnigma
Also, there has to be some sort of mechanism for heat, and then something to
actually generate it. All this is going to be is the engine to turn it I
believe...

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TylerE
Sterlings are normally run on solar heat.

~~~
colanderman
I don't know why you're being downvoted. One of the primary uses of Stirling
engines, especially for off-grid homesteaders (at whom I'm sure this is aimed)
is concentrated solar. All you need are a giant Fresnel lens (~$100), some
black metal to act as a collector, and heat transfer compound to attach that
to your Stirling engine and you're off to the races.

~~~
damoncali
Not a downvoter, but maybe it was the "normally". The cool part of a Stirling
is that it is indifferent to fuel.

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TylerE
That's true, but in the real world it's fairly uncommon to see actual burners
in use, outside of machine shop projects and the like.

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retube
Hmm. I see a few practical issues with this. I need to keep a fire burning the
whole time? Not practical for many (most) homes and also will result in a lot
of wasted heat.

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Volodesign
We've given some thought to this - one idea we are kicking around is embedding
a heat capacitor in the engine, kind of like a battery for heat so that we can
even out the heat input to the engine - The heat capacitor coule be a type of
insulated molten salt bath.

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tord_f
Great, if I had enough space I would build one.

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JabavuAdams
Robotics.

