Big motor question.

[SimonH2]

I think there may be a a bit of confusion. The methane engine litterally only produces electricity through a generator, the majority of which is exported. This motor I was asking about is to chop the silage to feed into the digester plant. The methane from this plant is piped directly into the methane engine.

You tee into the methane line and pipe some of it to the engine that drives the chopper. Pretty well any petrol engine should be able to run on methane - and older carb engine is often the easiest to do.

As long as you have a decent battery and starter, you should be able to start on gas (ie you won't need to use petrol at all).

As you already have an engine running off gas, you should be able to see how that's set up.