Woodgas Storage

[renewablejohn]

If you're planning to run 'petrol engines' (ie spark-ignition), then feeding into air intake is as good as it gets (the modern generation of CNG kits uses injectors, but these only inject into the manifold like most petrol injection systems - in fact, if you look at car engines under full load, the injectors are open nearly 100% of the time - so they are no different from a carb in that they are constantly feeding fuel into the manifold regardless of open/close status of valves).

If you are running a diesel engine, then you need to use an ignition conversion kit if you want to run 100% gas. Ken recently posted a really clever arduino(?) based ignition kit for a Lister CS. Ignition mapping can be quite complicated for a car engine, but for a stationary engine, which is run under constant load, it would be pretty easy.

Incidentally, petrol and diesel engines have similar efficiencies at full load - so if you operate a petrol generator with throttle wide open (or not there!), then it will be almost as good as a diesel engine.

If you want gas for vehicles, why not look into anaerobic digestion? It's slower than woodgas production, but it's more efficient in conversion (can't find figures for either - anyone know?). Methane is far easier to store under pressure than woodgas as it doesn't have hydrogen to leak through the metal. And methane is 6kWh/m3 - much higher than woodgas (and I can get you a cheap compresor for methane     )

AD is not an option as it is a by product of the gasifier we we want to utilise. For normal power generation we do not have a problem as we are using a gas turbine to generate electricity which produces power dependent on the quality of the gas which we can input hence the need to get rid of the Nitrogen and CO. All the engines we convert will be diesels so looking for direct injection and spark ignition.  Would the methane compressor be suitable for woodgas if the Nitrogen and CO could be extracted. If we do extract Nitrogen what could we do with it. I know it is used as fertilizer but the process looks complicated.

[Ivan]

There's nothing much you could do with the nitrogen. The atmosphere is 70% nitrogen so there's no shortage of the stuff, and it would be a lot 'cleaner' than nitrogen extracted from woodgas. I guess it could be useful where you want to remove oxygen from something to stop it burning or decomposing, but can't think what.

The compressor would work ok on the gas, as long as you get rid of any tar (I think that can be a problem with woodgas, so you need to make sure this is filtered out (cyclone?) and cooled to condense anything that didn't get removed by the filter) and any sulphur/phosphorus impurities (if present) - as this would make it acidic and corrode the compressor.

I only know of two commercial direct injection systems. First is manufactured by a company called Vialle in Holland (for liquid LPG, NOT CNG). It was used on production LPG Ford Transits, but was complicated and suffered many problems, and I believe it was eventually withdrawn. Think they are promoting a new improved version of the system, these days. it required a specifically designed inlet manifold, so was only sold to car manufacturers (rather than retro-fit). The other system was a dual fuel double-injector system for heavy diesel earthmoving equipment that fired some diesel and some CNG into the cylinder. It was manufactured (and patented, I think) by Catepillar(?). The dual-fuelling got around the problems and reduction in efficiency caused by converting to spark ignition. If you want a really down-to-earth DIY approach, have a look at L.John Fry's 1950's books on biogas - he ran diesels on natural gas 24/7 for all his power in S.Africa - definitely a man before his time.