Looks cool, but I assume it lags a ton? That's the thing that keeps me away from anything else than wind+nuclear.
I have been toying with the idea of a tree farm based upon a logger and filler combo for my 7x7 tree farm. This just convinced me.
Possible suggestion, I thing scaffolds burn for the same length as wooden planks, but are cheaper in terms of amount of logs required for a stack. That would make your farm more effcient. Also, in terms of space, why not make that line of biogas engines vertical?
Of cause, I burn scaffolds, there is a scheme for crafting them at http://www.youtube.com/watch?f…page&v=pgB-4sVAcoo#t=462s 
Vertical engines stack is possible, but it makes maintenance and redstone signal layout a little more complex.
engines are always on so you can use BC gates on the pipes that feed biomass set to emit redstone always
also golden conductive pipes lose some energy over distance so use less of those and place transformers closer to engines and use more cable...more efficient.
you can also use the wood in coke owens to get charcoal and use the creosote in biomass engines for 60000 mj per bucket at 4 mj/t
those can be underground so it's on the same chunks and all you need is a bit of clay.
When RP2 is updated you could try using the RP2 tubes with the regulator, it puts things into stacks of a specified size so they don't create as much lag (I believe stacked items are just a single entity).
Think of the amount of BC energy you get from this... God.
