How much CO2 can spark ignition gas engine accept?

May I know the maximum amount of CO2 in syngas composition that can flow into the spark ignition gas engine ? Also what is the maximum pressure of syngas that can be accepted by the engine carburetor?

as long as the Oxygen ratio to the combustible is correct for good total combustion, you can replace all other with Co2…

So, technically, you can use 20% O2 with 80% Co2 to replace the normal air…


so if the syngas entering engine has 80% CO2, I just have to add 20% later on for combustion?

i think you need to rephrase your original question…
What is your native language ?

Malay Indonesia… i am in your neighborhood :grin: Thailand

The less Co2 you have in your syngas, the better your gasifier is.

But, there is almost no restriction if you have enough CO and/or H2 available for the combustion

Malay Malaysian…:smile: So, there are 13% of CO2 in my syngas thats going to the engine. I will be using high pressure water scrubbing to remove CO2. But I am afraid that the output pressure will be too high for the engine…so I am reducing the pressure for scrubbing but this will reduce the CO2 removal efficiency to (>80%) which is still high. So is it ok for the engine to receive some CO2, around 190m3/h ? I also need to know the max pressure of gas than can enter the engine carburetor

There is no problem with 13% Co2 going to your engine, what is the other parts of the gas ? %CO, %H2, %CH4 ?


CO - 61.7 %
H2 - 1.72%
CH4 - 2.62 %

Do u know about the max pressure of gas than can enter the engine carburetor?

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Thats good quality gas, what engine and what is the compression ratio of that engine ?

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I am using a spark ignition gas engine and the compression ratio is 14:1. The ratio depends on volume and clearance volume of cylinder. However, atm the engine only produces 170kW. I am still looking for an engine tht can produce larger amount of electricity( >1MW) . Any suggestions?

Azlina, you can’t actually pressurize a carburettor. It has vents in it that will leak. The bowl gasket might blow out. The higher the compression, the more power you need to fire the spark plug. There is a DIY solution for a hotter spark;
As far as a bigger engine, there aren’t many choices. There was an old GMC V-12 that had spark plugs. The big Hall-Scot engines were used in buses. The Allison and Rolls Royce were used in planes. With enough machining work, there are a lot of diesel engines that can be retro-fitted with spark plugs. You don’t need to fit a distributor. It all depends on what you can find.


So i need to use a pressure regulator after my scrubber to bring down the pressure of gas before it enters the engine. Wht type of pressure regulator shall i use? I need to reduce the pressure from around 7 bars to 3 bars.Clearly this has to be a non-relieving regulator to prevent gas loss.

1 mega watt? from an ICE? Good luck with that, you will need a min of 1400 horsepower at your running RPM!! 1400 HP at 1500 rpms = one big engine!!!

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What might be a better option is to team a bunch of systems together. Once they are synced together the engines become locked to one another. electrically. This will make the whole system much more stable than a single engine as if one of the systems has a hiccup the others will carry it along. It would also be more practical to feed a team systems vs building a HUGE hopper system. You could build a centralized system to feed teams of systems. Also this would be more beneficial for servicing as you could take one machine down at a time to perform this with out losing power. You could run at 3000 rpms to reduce the required machines, I think if you went with the 8 ltr engines running at 3000 rpms you could achieve around 80 kW output pr unit.


I see…will look into that matt…thnks a lot! :construction_worker:

I don’t even begin to understand your gas production at those pressures, but I think what you may want is a propane carburetor. They receive propane from a pressure tank and feed it into the engine as demanded.


Mitsubishi Industrial makes IC engines to fuel off of fossil coal “coke” made off-gasses on the coke CO as a motor fuel.
This off-gas can have up to 30% CO2 from the coke making possess.
They use the IC engine to burn-up/clean-up this off-gas and make electrical power for the plants electrical power needs.
Net look this up.
Steve Unruh


Hi Azlina,
Sorry for keeping you waiting…
Most manufacturers have their equipment delivered with a suitable gas pressure reducer, they require your gas flow with a pressure about 300mmwc.
I have a supplier that works with Cummins, they build special for the gas we use.
Another option is CAT

Both manufacturers are able to meet your criteria and are most helpful with any inquiry…