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DIY Gas Turbine Generator - Wood Powered

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gadget

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Discussion starter · #1 ·
I am 100% off-grid. I have plenty of solar when there is sunshine. I have been thinking about how to make power from the resources I have around me vs bringing in outside fuel. Also, and this is important, It needs to be simple mechanically. The problem with piston engine generators is they wear our really fast and they have lots of parts to fail.

Most of the time off-grid when you are low on solar you also need heat so CHP is a must.

Best thing I could come up with is a gas turbine. The only real downside I can figure is the low efficiency. But, if I'm looking at 5%, thats around 500w for a 30,000 BTU heater worst case scenario. Thats plenty of power to keep batts topped off on those cloudy days.

I know allot of you are going to come in and say I should just run wood gas to a gen or sterling motor etc...please don't unless you have actually ran one for a season.
.
Advantage of a gas turbine;
  • can get the turbine for $100 USD on ebay ( auto turbo )
  • cheap RC motor generator - ebay
  • only one moving part on turbine (not including oil pump or bearings on generator)
  • very reliable / high hours running between rebuilds
  • easy cheap and fast to rebuild
  • can be compact

Cons;
  • low efficiency
  • noisy
  • DIY controls

IHI made a 2.5kw compact unit a few years back with basically an auto turbo charger. I wish they where more common but they only made a few of them.

I think I might start a build thread this spring but I am not sure yet what forum would be best. How many here are interested?
 
#2 ·
My design is to to use a steam engine. Liquid "lead" pumped threw the flash boiler by electromagnetic field (MHD) is the first part. Inverted aluminum block 4 cylinder engine, no rust . High temperature O-rings for piston seals. Grease zirks on all the bearings. Low rpm like 360 needs a 10-1 gear increase for the generator. Make or weld up the cam to be a two stroke. Electric valves to admit high pressure steam in the spark plug holes. Distributor redesign to be the flyball governor.

Being inverted less chance of being water locked, stainless valves are rust resistant.
 
#3 ·
Interesting concept. DC system might be easier to regulate output. Regulating a 120 vac system looks daunting. Using a 5 to 50 v dc source to charge a battery, using a dc to dc converter is very doable. 80% efficiency or better is typical. The battery could drive an inverter.
I'm both an engineer and electrician and should have more time after the first of the year.
 
#4 ·
I think they made more than a few turbochargers. All diesel pickups use them, tons of cars use them, they are actually pretty common.
Now, not sure why you think piston engines wear out really fast, are you running them without oil or something?

It seems like you are trying to reinvent the wheel when proven systems already exist, but if you like a challenge and to build things (like I do) go for it...
 
#5 ·
gungatim said:
I think they made more than a few turbochargers. All diesel pickups use them, tons of cars use them, they are actually pretty common.
Now, not sure why you think piston engines wear out really fast, are you running them without oil or something?

It seems like you are trying to reinvent the wheel when proven systems already exist, but if you like a challenge and to build things (like I do) go for it...
Click to expand...
Turbine is going to require some heat exchanges- and a boiler isn’t the simplest think to build safely. Without heat exchanges every bit of heat required to raise the water to 220 degrees or so plus the heat of vaporization is wasted- only the heat used to raise the steam from a few psi to your operating pressure can be recovered. The waste heat could heat your house, but some of that heat should be recovered to preheat the “charge”
water. And you will need a injection pump or Venturi injectors. How do you intend to to govern the turbine? You can’t let water condense on a turbine.


And yes I think wood gas feeding a IC engine is far more practical-and some friends did it, so I’m aware of the maintainance issues.
 
#6 ·
I like all the ideas and postulations, I really do. Now for some photos and specs of operating systems that can run for a length of time. I don't care if they are cheaper or whatever just something usable that can be maintained for the net 20 or so years without parts from china.
Right now I have enough ICE powered generators and wood around me for the next 20 years.
 
Discussion starter · #7 ·
charliemeyer007 said:
My design is to to use a steam engine. Liquid "lead" pumped threw the flash boiler by electromagnetic field (MHD) is the first part. Inverted aluminum block 4 cylinder engine, no rust . High temperature O-rings for piston seals. Grease zirks on all the bearings. Low rpm like 360 needs a 10-1 gear increase for the generator. Make or weld up the cam to be a two stroke. Electric valves to admit high pressure steam in the spark plug holes. Distributor redesign to be the flyball governor.

Being inverted less chance of being water locked, stainless valves are rust resistant.
Click to expand...
I have always liked the 3 cylinder compounding steam motor. One of the goals is to avoid many moving parts.

Practical said:
Interesting concept. DC system might be easier to regulate output. Regulating a 120 vac system looks daunting. Using a 5 to 50 v dc source to charge a battery, using a dc to dc converter is very doable. 80% efficiency or better is typical. The battery could drive an inverter.
I'm both an engineer and electrician and should have more time after the first of the year.
Click to expand...
I'm wondering if a solar MPPT charge controller would work. Someone mentioned the diodes in the rectifier would need to be able to handle full short current for when the MPPT tracks.

gungatim said:
I think they made more than a few turbochargers. All diesel pickups use them, tons of cars use them, they are actually pretty common.
Now, not sure why you think piston engines wear out really fast, are you running them without oil or something?

It seems like you are trying to reinvent the wheel when proven systems already exist, but if you like a challenge and to build things (like I do) go for it...
Click to expand...
I have a lister clone 8/1 CS, its a slow speed hand crank diesel. Its about as good as you can get for running hours/life. Still, run it 8 hours a day and you better keep some rings and bearings on hand. Its simple but it has metal parts that move back and forth. The turbo just has the 1 shaft that rotates on a film of oil in brass bushings. A T3/T4 can be had on ebay for pretty cheap.

country_boy said:
Turbine is going to require some heat exchanges- and a boiler isn’t the simplest think to build safely. Without heat exchanges every bit of heat required to raise the water to 220 degrees or so plus the heat of vaporization is wasted- only the heat used to raise the steam from a few psi to your operating pressure can be recovered. The waste heat could heat your house, but some of that heat should be recovered to preheat the “charge”
water. And you will need a injection pump or Venturi injectors. How do you intend to to govern the turbine? You can’t let water condense on a turbine.

And yes I think wood gas feeding a IC engine is far more practical-and some friends did it, so I’m aware of the maintainance issues.
Click to expand...
This would be a gas turbine and not a steam turbine. I still have not found anyone successfully running a wood gas generator for months on end. Plenty of talk but I have not seen any hour meters ticking away.

montana Bill said:
I like all the ideas and postulations, I really do. Now for some photos and specs of operating systems that can run for a length of time. I don't care if they are cheaper or whatever just something usable that can be maintained for the net 20 or so years without parts from china.
Right now I have enough ICE powered generators and wood around me for the next 20 years.
Click to expand...
Thats thinking ahead. I believe we will see more supply chain issues going forward.
 
#10 ·
gadget said:
This would be a gas turbine and not a steam turbine. I still have not found anyone successfully running a wood gas generator for months on end. Plenty of talk but I have not seen any hour meters ticking away.
Click to expand...
that would be for a STEAM turbine, not a gas turbine. Gas Turbines dont use steam except as a possible second stage in a combined cycle plant.

Months on end- no, I think it’s inherently a batch operation. But running it for 6-8 hrs a day for 6 months- yes they did it. Drove it from eastern US to CA. Wood gas generator is still going, no longer connected to a vehicle.
 
#15 ·
irv818 said:
Wonder if that is enough to produce useful output from a turbine.
Click to expand...
Probably. CO doesn’t burn fast- not sure what velocity would be in a small turbine, and if that would be a problem.

I‘m thinking the chances of success for a homemade combustion turbine are slim. But I’m no expert on combustion turbines. Helped a Solar guy work on one out on on oil rig that I was stuck on for a week.
 
#16 ·
gadget said:
I am 100% off-grid. I have plenty of solar when there is sunshine. I have been thinking about how to make power from the resources I have around me vs bringing in outside fuel. Also, and this is important, It needs to be simple mechanically. The problem with piston engine generators is they wear our really fast and they have lots of parts to fail.

Most of the time off-grid when you are low on solar you also need heat so CHP is a must.

Best thing I could come up with is a gas turbine. The only real downside I can figure is the low efficiency. But, if I'm looking at 5%, thats around 500w for a 30,000 BTU heater worst case scenario. Thats plenty of power to keep batts topped off on those cloudy days.

I know allot of you are going to come in and say I should just run wood gas to a gen or sterling motor etc...please don't unless you have actually ran one for a season.
.
Advantage of a gas turbine;
  • can get the turbine for $100 USD on ebay ( auto turbo )
  • cheap RC motor generator - ebay
  • only one moving part on turbine (not including oil pump or bearings on generator)
  • very reliable / high hours running between rebuilds
  • easy cheap and fast to rebuild
  • can be compact

Cons;
  • low efficiency
  • noisy
  • DIY controls

IHI made a 2.5kw compact unit a few years back with basically an auto turbo charger. I wish they where more common but they only made a few of them.

I think I might start a build thread this spring but I am not sure yet what forum would be best. How many here are interested?
Click to expand...
I'm still trying to wrap my head around what you are trying to do.


A micro gas turbine with generator and heat recovery? Built from parts from Ebay? and fueled with wood?
 
Discussion starter · #17 ·
PA_Robert said:
I'm still trying to wrap my head around what you are trying to do.


A micro gas turbine with generator and heat recovery? Built from parts from Ebay? and fueled with wood?
Click to expand...
Yes.

Do any of you remember my thread about the DIY freeze dryer?

DIY Freeze dryer - I think it is possible

Many thought it couldn't be done and I did it under $100. I refined it over the years and it works very well with less power then a harvest wrong.
 
#18 ·
gadget said:
Yes.

Do any of you remember my thread about the DIY freeze dryer?

DIY Freeze dryer - I think it is possible

Many thought it couldn't be done and I did it under $100. I refined it over the years and it works very well with less power then a harvest wrong.
Click to expand...
Very good. Let me do a little research about wood gas, automobile turbos and read through the freeze dryer thread.

I have an extra turbo assembly for my F350 6.0 powerstroke. I'll dig it out and see how the shaft could be modified for an addition of a small generator and independent lube oil system. Since speed control (AC frequency -i.e 60hz) will be a challenge, as Practical suggested, a DC generator with a voltage regulator will probably be best.

I am a mechanical engineer and have been working with gas turbines since 1997. I've done mostly installations and commissioning & start up and I recently got back into the maintenance side of power generation.

Some initial problems to overcome...compressing the wood gas to inject into a compressed air stream for combustion, starting the turbine will need compressed air or electric start motor and an ignitor, and getting the turbine to a high enough speed for self sustaining continuous combustion.
 
#20 ·
gadget said:
Yes.

Do any of you remember my thread about the DIY freeze dryer?

DIY Freeze dryer - I think it is possible

Many thought it couldn't be done and I did it under $100. I refined it over the years and it works very well with less power then a harvest wrong.
Click to expand...
A do it yourself freeze dryer is fundamentally easy. Your only piece of technology is a vacuum pump that you need to not destroy with the moisture removed. Some not challenging structural issues to create a vacuum chamber, and a heat source for the heat of vaporization. Getting it to work well is just a matter of managing the vacuum pump.

But a gas turbine- you are talking about designing high speed components from scratch, and creating fan blades that stand up to the heat of combustion- and in the of case of wood gas, tar buildup. Automotive turbochargers arent designed with an output shaft, and they are designed to interact with exhaust gases after they have released their energy via the Otto cycle. In a gas turbine, that energy release is at the turbine. Plus you’ve got to design the combustion chamber between the compressor and turbine to ensure maximum energy release before exiting the turbine. and you need a pump on your wood gas to inject it at enough pressure to mix, while overcoming compressor pressure.

I though you wanted a steam turbine which is easier, and was some what common before electric power transmission.

if this was easy or practical you would see turbines on small generators like sign boards and light
plants that have long service life, as well as APUs on semis.
 
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