small engine for small electric generator

[stewcraine]

Hi all,

Sorry for this nutty sounding message , but I was looking for some advice, and this seemed a good place for it. I flew model aeroplanes with my Dad as a kid, so am familiar with small fast diesel and glowplug engines, but recent years have found me helping villages get electricity. The smallest off-the-shelf diesel generator is a 2.2 kW Yanmar diesel, but I was thinking if a model train or plane engine or similar exist that might be even smaller, to which I could hook up a little AC or DC generator.

I've helped millions of people access solar, and am very familiar with that, but there's a spot also for a product of relatively low initial cost ($50-200) and less than 1 litre per hour of operating cost for fuel (which is what a Yanmar takes - am hoping to get down to 0.1 L/hour). Listers were also popular, and because they're slow, they could take vegetable oil pretty well too. Todays' equivalent is probably a Changfa from China, but again, about 2-3 kW and taking about 1 L/hour.

Stirling engine, scaled diesel, anything, I don't really care. Just trying to get a few tens of watts generated (my solar kits are 1-10W per household, so for a 50 household village, need 50-500W, basically).

Any thoughts? Thanks in advance...

Regards,
Stewart Craine
www.villageinfrastructure.org

 

[MCRIPPPer]

i have thought of making a model generator just for fun. you seem to have found a good use for one. but i think it would be more efficient and reliable to have one larger generator run the whole village.

 

[Wizard69]

Hi all,

Sorry for this nutty sounding message ,

How does one nut stand out in a jar full of nuts?

but I was looking for some advice, and this seemed a good place for it. I flew model aeroplanes with my Dad as a kid, so am familiar with small fast diesel and glowplug engines, but recent years have found me helping villages get electricity. The smallest off-the-shelf diesel generator is a 2.2 kW Yanmar diesel, but I was thinking if a model train or plane engine or similar exist that might be even smaller, to which I could hook up a little AC or DC generator.

A DC generator would be easy, just retask a brushed permeant magnet motor. Since DC motors come in endless sizes, you could easily build a handheld power source. Go slightly bigger and drive a small auto alternator.

I've helped millions of people access solar, and am very familiar with that, but there's a spot also for a product of relatively low initial cost ($50-200) and less than 1 litre per hour of operating cost for fuel (which is what a Yanmar takes - am hoping to get down to 0.1 L/hour). Listers were also popular, and because they're slow, they could take vegetable oil pretty well too. Todays' equivalent is probably a Changfa from China, but again, about 2-3 kW and taking about 1 L/hour.

Low operating costs means low power. At some point it just isn't worth it.

Stirling engine, scaled diesel, anything, I don't really care. Just trying to get a few tens of watts generated (my solar kits are 1-10W per household, so for a 50 household village, need 50-500W, basically).

10 watts per house? Is that really helping people? I don't want to dismissing your efforts but these projects sound more like an attempt to make you feel good about yourself.

Any thoughts? Thanks in advance...

Regards,
Stewart Craine
www.villageinfrastructure.org

Seriously anything less that 500 watts seems like a complete waste. That is unless your goals are extreme portability. Even 500 watts is very limiting, you really want enough power to run power tools. Ultimately tools are what liberates people.

 

[lohring]

Ohlsson and Rice once made a small generator. See http://gasengine.farmcollector.com/gas-engine/searching-for-ohlsson-and-rice-engines.aspx Lohring Miller

 

[MCRIPPPer]

im hard pressed to think of anything that uses less than 10w!

 

[Wizard69]

If you look towards the hunting/fishing/outdoors suppliers you can find small generators that go as low as 500 watts of output power in portable designs. For the usage intended I can't see where a DIY project makes sense, you really need a mass produced solution. The other end of the spectrum is that the US Army was looking into very small generators to be carried by solders to power/recharge all of their little devices, but I'm not too certain much came of that.

On a slightly larger scall these guys have an interesting approach: http://www.bladonjets.com/. Here is something on the very small end for a turbine generator: http://www.powermems.be/gasturbine.html. Here is a solution that looks like it is ready to ship: http://www.mtt-eu.com/. Here is an interesting paper on the subject: http://www.bioturbine.org/Publications/PDF/microturbine-01-HILTECH.pdf

You may be wondering why I focused on turbine micro generators above. There are a couple of reasons. For one the units are extremely small for a given output. Another reason is few parts to deal with. Some of these machines have one moving part with even the common ball bearing replaced with air bearings, this means long trouble free run times. As long as you have fuel one of these units could run for three years straight. In that time a diesel generator would have gone through at least four rebuilds along with multiple servicings.

To put it plainly most internal combustion engine power sources wouldn't be worth the trouble unless the area you are putting them in has the support infra structure in place. If the area has the infrastructure in place then there is no point to your project. As much as I hate solar panels, they are likely a better solution for areas well away from modern infrastructure.

 

[oldtruck]

visit your local junk yard, and old construction equipment Look for an generator. There are 6 to 24vdc and you will need a voltage regulator.
Alternators will work GM a had a 25 amp self excitation with built in reg. Stull available at most auto parts it will take about 5 hp to run at 1100 rpms.

 

[Entropy455]

A liter of gasoline contains approximately 31,700 BTU of energy. If this liter of fuel is spread out evenly over one hour, the engine fuel consumption would be equal to 8.81 BTU per second (actual heat input into the engine.) Assuming a thermodynamic engine efficiency of 30%, the mechanical crankshaft output would be 2.64 BTU per second (rotational power).

Assuming a typical generator efficiency of 70%, the actual electrical power generation would be about 1.85 BTU per second. Converting into Watts(where 1055 Joules is equal to one BTU, and one Joule per second is equal to one Watt) – a typical gasoline powered electric generator will produce about 1950 Watts of electrical power, while consuming 1 liter of gasoline per hour.

This is just enough power to run a single 15 ampere 120 volt circuit. It would be great for camping – assuming you only have one small load to run at a time. . . . .

 

[aonemarine]

Think Steam!!

 

[Lakc]

Entropy seems to know the numbers involved. Diesel being the most efficient in the internal combustion range, (excepting turbine?) and steam being the least efficient. Stirling supposedly outdoes them all.
Slow running generally means more mass rotating, which is the opposite of what you get downsizing motors.
I would not discount the usefulness of even the small amounts of electricity, dependably generated, and what it could mean to some remote village that has net even heard of the grid. LED lighting, charge a battery, run a radio, all could mean life or death in some situations.

 

[mu38&Bg#]

Small engines are expensive due to low volume and limited market. I've built generators based on RC hobby engines. You need to come up with control, regulation, etc. The Chinese 50 or 80cc two stroke gensets is about as cheap as you can get but you have to burn gasoline. A 10W generator would need to be developed from scratch and the cost would be prohibitive.

A genset running at less than full load would burn less than max rated fuel rate, but may or may not be as efficient. A few solar panels seem to make more sense but I understand that they are targeted for theft.

Greg

 

[stewcraine]

Thanks, Entropy455 and others. Yes, 2kW for 1 L/hour is spot on what is available in the market today. I'm aiming for 0.1-0.2L / hour. Even at similar capital cost. I don't mind the DIY aspect, Wizard69, because if you guys can make one, I can take it to China for mass production. I lived there for 4 years building up www.barefootpower.com and we shipped 200,000 units and more of products I slapped together from rough prototypes compiled from off-the-shelf product. I'm looking to you guys to see if such a small engine can be produced - sourcing the DC or AC generator is of zero concern, I just need something to turn it around. A Stirling engine is likely a good chance of being successful. Microturbines of 25kW are way too big for me, am aiming at 50-500W. The powerMEMs link is interesting and good - I've seen the Japanese have made something similar for robots, but it costs a bomb, and the Japanese rightly point out that something rotating at 500,000 rpm is not trivial. A slower stirling engine sounds better to me....

Cheers,
Stewart

 

[aonemarine]

http://www.cyclonepower.com/whe.html

 

[stewcraine]

Thanks for the waste heat engine link. 8kW is about 20 times larger than I'm hoping for. But interesting!

Stewart

 

[mu38&Bg#]

Large low RPM engines have some inherent traits that will be lost when going to a small high RPM engine. What type of fuel are readily available? Oils? And what about service components for your custom engine?

Greg

 

[MachineTom]

Stewart, In looking at what you want a small IC engine is very inefficient compared to a Listen diesel engine. Oil based fuel is generally expensive in most places in the world. What about steam type engines that can burn local solid fuels, It would seem better for a village to gather and burn local fuel, than to generate cash somehow to purchase oil based fuels.

 

[Tin Falcon]

Maybe one should look upon history.


this any fuel quite unit put out just under 50 watts.

http://www.royalsignals.org.uk/photos/steam.htm

Tin

 

[aonemarine]

Nice find Tin! Thats the beauty of steam, easy to source fuels.
Side note, what about wind power?

 

[stewcraine]

Hi again all,

Dieselpilot - kerosene lamps are in every house, so kero/paraffin is pretty widely available. Everyone cooks indoors with wood or charcoal, so this is available. Diesel and gasoline are pretty well available too, for motorbike transport, small boats and farm equipment. I've built an after-sales support network of over 500 retail points serving 400,000 households in my last company, so am confident we have the networks to keep support going.

MachineTom - Yes, am thinking something that burns on the same stuff that ride-on trains burn on, using a similar engine of not terribly high rpm (like a plane engine) is the way to go

Tin - Brilliant! Simply brilliant! This, and the Tiny Tiger posted earlier, and both winners for me. Note that it uses a "model steam engine" - that's exactly why I'm on this site - you guys know how to make those, or even guide me towards where I could buy one. Now I need to try and track down whoever took these photos or made this unit (Stuart Turner, or other). Even if the upfront cost of this was as much as a 3kW diesel, the running costs would be a heck of a lot lower. If it can run on wood, awesome - wood costs $20-50 per 1000kg in villages, and it would take ages for this little puppy to chew through a tonne...

Thanks again! Now for the detective work. But if any of you think an off-the-shelf model steam engine has potential, please let me know. Doesn't have to look like a train or be beautiful or anything...

Cheers,
Stewart

 

[stewcraine]

Just found a YouTube of the Tiny Tiger too.....they're out there...!
[ame]http://www.youtube.com/watch?v=fLsXPfZl9E0[/ame]