Diesel CHP Charcoal system

Firstly, thanks to all. This is a great site with lots of information for the beginner :slight_smile:
@Matt, your older videos have been a great inspiration.

I have settled on a Charcoal system for my generator CHP project.
The engine/generator is built and gas fuel system is now in the design stage.
@Matt, I watched some of your CHP videos from 7 years ago. WOW ! you built some amazing stuff man.

My question is this:
Is there an optimal temperature to maintain in the coal bed, and what is it?
I could then use a thermo-couple sensor and micro-controller to throttle the engine exhaust cooling gasses to the bed using a servo butterfly valve to regulate burn temperature.


Bump :slight_smile:
Target temperature range to maintain?

1 Like

It depends on the engine, the temps are typically spot on as long as you’ve sized the gasifier correctly to the engine.

We would need more specific details to be able to be more helpful.

1 Like

Thanks Cody.
So perhaps the question I should be asking is “whats the rule for sizing an updraft charcoal burn chamber in relation to a 1.3 liter engine”?
I understand the relationship between wood gasifier burn tube sizing vs engine size, but how are charcoal gasifiers sized vs engine size?
Thanks kindly

1 Like

Charcoal gasifiers also rely on a range of reactor body sizes, you don’t want to go too small depending on the engine. The main dimension is the nozzle, because a charcoal gasifier is really making Air Gas. The hot charcoal is robbing any oxygen molecules it can find and leaves you with CO, Nitrogen, and Hydrogen from moisture in the air and from any water drip you add to the nozzle.

With a charcoal gasifier you gain a bit of self insulation from the fuel, carbon makes a very good insulation. That’s the main reason why you don’t want to use too small of a reactor body.

Eddy Ramos has made a very nice guide to building an updraft charcoal gasifier, it includes a formula to configure your ideal nozzle size.
Here’s a direct link to download the PDF in English:


Bear in mind with updraft, you want your charcoal to be in the 1/8" to 3/4" cross section size range and to be very dry. It also must be entirely converted to charcoal, brands(halfway between wood and charcoal) should be tossed into the next batch for charcoal.

With an updraft, any tar made will go upwards with the gas.

A cloth bag filter works very well to catch any tar, and it will instead clog the filter to save the engine.

Also in an updraft, the exiting gas is almost ambient until you begin to be low on fuel, the unreacted charcoal above the active zone slows down the exiting gas and allows it to cool down.

What diameter of reactor body were you thinking of using? For that engine size I’d go with no less than 14" in diameter, with my 2 Liter Mazda pickup I used a standard 55 gallon drum of 22" diameter.

If I may add, a 1.3 Liter engine is plenty big enough to run a raw wood gasifier efficiently.


Thanks for that guidance.
Regarding your question about what size reactor body I was thinking about… I have no idea. :slight_smile:

My knowledge in fuels for power generation is in Biodiesel, waste veg oils, and reconditioned waste oils. Gasifiers are a new chapter for me. That .pdf looks very useful, thanks for the link.
I’m sure I will have many more questions, until then I’ll be studying and lurking :slight_smile:

This is the engine…
Single cylinder running at 400 to 650 rpm. (8 HP). Yes, it’s 1.3 liter.
I suspect it draws about the same amount of gas as an 8HP 3600 rpm engine.
My concern is the negative inlet pulse that it creates with every other stroke.
I may need some kind of inlet pulse buffer. I will attack that problem when I get there.



1300cc single cylinder would be an awfully violent pulse coming out of the engine’s fresh air intake. People already combat it with 400cc and under engine sizes.

Lengthening the intake runner can always help a bit, but that will slow down the engine’s response to stoichiometry changes.

1 Like

Yes, I suspect a small displacement multi-cylinder engine would be a much better candidate.
I will be on the lookout for a better suited engine.

1 Like

I don’t know where you’re located, but it could be easy to find a Kubota engine online. Water cooled 3 cylinder diesel usually in the 700+cc range. I think as is they’re roughly 20 Horsepower, maybe more. You could maintain your homemade diesel fuel as a backup/pilot. Would also be easier to get replacement parts for spontaneous repairs. My family has owned a Kubota diesel tractor for decades and the only repairs we’ve had to do are related to the drivetrain and hydraulics, and the occasional water in the fuel issues.


That is one great feature of diesel - the fuel is content to stay stored until needed. Gasoline is always trying to turn itself into varnish.


Its seems that powering large bore single cylinder engines is do-able with wood/charcoal gas.
Here is the project where All Power Labs converted a 1.3 liter Lister Engine to run on gas from a wood gasifier.

The unit produced 2.75 KW of power from the generator…


Never said it couldn’t be done, just that the pulse is something you will fight with and throws off any automated air mixers.


glister Veggie,
I may be Mr. Obvious here, that Lister 1.3L in the APL video has been spark ignition converted. Screen shots that second video: Sparkplug outlined yellow, Coil=green, MSD ignition box=blue.
There is a flywheel pickup also. :cowboy_hat_face:
Very good engine. Rare as can be in the USA. :star_struck:


@Mike Reynolds
Hi Mike, Yes Ken converted that engine to spark ignition using an Arduino module tied to the flywheel pickup sensor. My main reason for posting that vid was to show that the large intake suction pulses created by bigger single cylinder engines can still work with gasifiers.

Here’s another example of Charcoal gas with diesel fuel pilot ignition (no spark plug).
Koen Van Looken running a large displacement single cylinder diesel.

If inlet pulses become an issue, I think I could fabricate a pulse bottle in the piping to help smooth out the flow. Should be interesting.