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Forum Index : Other Stuff : F & P Wood Gas Project
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Madness Guru  Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
I want to build a battery charging generator as a wind/solar backup unit. My plan is to use a 4 stroke OHV lawn mower engine. I have a few of these which are chinese copies of a Honda engine. They appear regularly at the local tip shop usually with just the pull start needing some attention. They are used on Victa V40 mower and others such as Sanli. I have one set up on a piston pump which only needs 1/2 Hp to drive it and this has been very reliable. I am looking at using the information from here woodgas microgasifiers to build the gasiifer. Fuel source would be chipped wood which I can get lots of for free. The Engine I plan to use is rated at 2.8 KW but running on woodgas I can only expect around 60 % or 1.68 KW. I have seen some information on the net about people running F&P motors at 1500 RPM and getting over 1 KW. Has anyone had any experience with this? To do this I would have to use a 2 to 1 belt drive. Any input would be appreciated, another alternative would be a direct coupled generator like an F&P but smaller diameter and designed to run at over 3000 RPM. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
If you are going for 3000 rpm then why not use a car altenator, a lot easier to run a belt around. Sometimes it just works |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Fitting pulleys and a belt is easy, I don't want to use a car alternator due to the inefficiencies. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
inefficiencies  is that true? I dunno!
the average power gennie is just under 2HP per Kw where is a car alternator compared to that? I have never really thought about it. I've seen a 100 amp alternator direct coupled to a GX160, I assumed it had heaps up its sleeve and that it was chosen cos it is the cheapest Honda motor, they make million$ of them. I'm confused, no wait... maybe I'm not... |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Car alternators are made to be small, light weight, cheap to manufacture and provide high output. They have very little copper and iron in them for the power they produce. When bolted to a 100+ horsepower car engine, nobody cares about how many horsepower it consumes to turn it. All people care about is how much it costs and how many amps it can charge the battery. They are a very poor choice for any type of energy efficient project. Try this yourself. Get a reasonable sized electric motor, couple it via a pulley to a car alternator and make yourself a very low cost high current battery charger. You might be surprised how little dc load current it takes to overload and slow the drive motor. The conversion efficiency for watts into the motor, and watts out of the alternator will be very disappointing. Lawn mower engine idea sounds good. With an extra heavy flywheel it could possibly be run at much less than full normal speed. An F&P should work well, or how about a large stepper motor used as a three phase alternator ? Cheers, Tony. |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
OK Madness, I have given this long enough for me to think about. I must have read that micro-gasifier website twenty times. The more I look at it the more I think it is very much like learning to juggle......with razor sharp knives! There is just too much that needs to be perfect for the thing to run properly, the learning curve needed to diagnose and fix problems would be way to steep for me. I would have to built a larger gasifier and run it for at least 6 months, as a heater or something, to get my eye in before I attempted a project like this. Hope you will post some photos of your project along the way as a bit of inspiration for me. I have a 1940's chev truck I want to fit a gasifier on but at the moment its just not happening. Lack of motivation. I'm confused, no wait... maybe I'm not... |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
As a different option you might like to have a look at this http://geetinternational.com/GEET%20-%20Small%20Engine%20Con version%20Plans%5B1%5D.pdf I dont know if its fact or fiction, but looks real in the video tests and works on almost any waste product. Sometimes it just works |
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| yahoo2 Guru Joined: 05/04/2011 Location: AustraliaPosts: 1166 |
I have had my interest sparked by this little beauty. It's a david brown tractor running on producer gas. About now you are probably thinking the same as I did, ...you know..like..ummm..wot eva!  It was a originally a diesel 
I didn't realise a diesel conversion was possible Built by Johan Linell there is some details on his interesting website "Around Sweden with wood in the tank" listed under Wood gas tractor 
Pretty sure the white stuff is icing sugar. I'm confused, no wait... maybe I'm not... |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Wood gas is only really viable if you have a huge volume of woodchips or sawdust available, maybe from a timber mill. Likewise methane from animal crap, if you just happen to have mountains of the stuff sitting around, then go for it. What is practical, and what works, depends mainly on what you have to start off with. If you already have an abundant heat source, a thermoelectric generator has no moving parts and would be very reliable. Making a really big one yourself would be a bit of work, but you would only need to do it once, and it would work off any high temperature heat source. Cheers, Tony. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
I have a virtually unlimited source of wood chips available, I just need to load it up and bring it home. My trailer will hold 5 cubic metres which should last a few months. What do you mean by a thermoelectric generator? Do you mean those thermo couple things? There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
Yes I am aware that small scale gasifiers are tricky, having the hearth continually agitated by a rotating cone doing 1 or 2 rpm may be the answer to what seems to be the biggest issue of the wood chips bridging. As for car alternators the disadvantages have been pointed out, apart from that I have stacks of Fisher Paykel motors as I repair the washing machines. Also the 3.75 HP honda clone lawn mower engines are readily available from the tip for $10 each most times the pull start needs some attention. So I plan to build so that the engine can easily be replaced when it wears out. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Yes thermocouple junctions, hundreds of them. No moving parts, nothing to wear out or go wrong. Just needs hot flue gas, and a cold outside temperature, and it works all by itself. Cheers, Tony. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
You must have very deep pockets at $20 plus a piece, unless you know a cheap source. There are the cooler ones that are a few dollars each but those that can be used to generate power are a different matter. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| MOBI Guru Joined: 02/12/2012 Location: AustraliaPosts: 819 |
Remembering back to high school days - I seem to think that we did low voltage (galvanometer range)experiments using thermocouples. I think they were made of junctions of a metal called German Silver and copper. Also from memory, any two dissimilar metals joined together and the junction then heated will produce a voltage across the ends. You might be able to make your own. I've often been tempted to have a go. Edit: german Silver, aka nickel silver (nickel, zinc and copper I think) David M. |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
No not those thermoelectric coolers !!! I am talking about completely homemade low cost thermoelectric junctions by joining two dissimilar metals. The "Seebeck effect". These thermoelectric generators have been around for over a hundred years, and just involve using two different kinds of bare wire with alternate hot and cold junctions. http://www.douglas-self.com/MUSEUM/POWER/thermoelectric/ther moelectric.htm Cheers, Tony. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
According to your link NASA achieved 6% efficiency. Unless you have information about a backyard build that is better I will stick to my original plans. "Right now the most important RTG in the solar system is the RTG that powers the Curiosity Mars rover. Solar cells do not work well on Mars, as they cannot function in either the Martian night or the Martian winter. Curiosity is therefore kept rolling by an RTG that contains some 5 kg (10 pounds) of plutonium-238. (not the plutonium-235 used in atom bombs) It is designed to power Curiosity for at least 14 years. The elecrical output is 125W at the start of mission; that will slowly fall to about 100W after 14 years. The initial thermal output is 2 kW. so the efficiency is still only 6% for what is presumably one of the most advanced RTGs in existence." There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
What was really after is information about running a F&P motor at 1500 RPM and what results I might get. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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| Downwind Guru Joined: 09/09/2009 Location: AustraliaPosts: 2333 |
By memory anything above about 700 rpm the power factor falls off greatly to RPM with the F&P, so at 1500 RPM the return will be not much greater than around 700 RPM. Sometimes it just works |
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| Warpspeed Guru Joined: 09/08/2007 Location: AustraliaPosts: 4406 |
Efficiency is only an issue when you are paying for the fuel. If waste heat is used, for example from the flue of a wood stove, anything you can recover is still something for nothing. Cheers, Tony. |
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| Madness Guru Joined: 08/10/2011 Location: AustraliaPosts: 2498 |
I have decided to go a different way with this project. I have built a Gasifier using the All Power Labs GEK design. You can download cad drawings and have all the parts cut on a CNC Plasma cutter as I have done. Although I had to make some modifications due to not being able to get the flexible gas lines they use for preheating the air. I am connecting the gasifier to a 5 KW petrol marine generator that I picked up on Ebay for $105, it would not turn over. The generator has a 1240 CC Nissan engine that runs at 1500 RPM, the same engine is used on a 7.5 KW version of the same generator set, so I have extra capacity in the engine to allow for the power drop due to running on woodgas. Turned out water had got into the cylinders. a hone, new rings and head gasket fixed it. 
All going well I will have the Generator running off the woodgas in the next few days. It should run for around 8 hours at full power off the 200 Litre drum full of chips. There are only 10 types of people in the world: those who understand binary, and those who don't. |
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