Making fuel for a gasifier in North America is a somewhat particular operation because of the commercially available equipment.  The goal is to make a large chip or chunk which flows gas readily to blow ash through the fuel stack.  Here is how I do it:

I generally use a tractor and a 3 point chipper in November when the leaves are off the trees.  Smaller homeowner size chippers make a chip that is too small for use in gasifiers.

A person on YouTube asked me how long the pile of chips in the video will run my gasifier so let’s do some math.

If I assume that the pile in the video is half a sphere, then the volume of chips created was:

Volume =(1/2)*(4/3)*PI*(R^3)

Volume = .5*1.333*3.14*(3^3) = 56.5 ft^3

From previous experiments I know that the density of my dry chips(9% moisture) is 8.94 lbs/ft^3 so the weight of dry chips created was:

Weight = (8.94 lbs/ft^3)*(56.5 ft^3) = 505lbs

I generally discard one third of my chips as fines so the dry fuel created in the video was:

Dry usable fuel = (2/3)* (505lbs) = 337lbs

The Gas Station feeding a 6kW, 389cc generator with no load at 3600rpm will consume 8.9lbs/hr so the run time for the pile in the video will be less than:

Time = (337lbs)/(8.9lbs/hr) = 37.8 hours

as load is applied.