[Gasification] biogas vehicle

[Harmon Seaver]

Roger Samson wrote:
> Kevin 
> 
> We have a paper coming out soon on the energy balances of the main
> alternatives.  
> 
> Roughly you can get about 6500 m3 (150 GJ) of biogas from 1 ha of corn
> silage. With corn ethanol you get about 3500 l/ha (about 72 GJ). Roughly you
> capture twice as much energy from farmland by using biogas as the energy
> carrier. 

   There is a very, very serious and major error in this calculation.
When you make the feedstock into ethanol, you have just as much food
left, and, in fact, much higher quality, much more digestible food left
over, in the form of the spent mash. So you are producing both food and
fuel.
   When you use the same feedstock to make methane, you might get more
fuel, but you get no food at all. And the fuel you get is highly
inferior to ethanol as a vehicle fuel simple because it requires much
greater modification of the vehicle and it is impossible to carry enough
methane to go very far.
   Plus, of course, the fact that corn is a horrible feedstock for
ethanol or methane, you can find a great many feedstocks that will give
you two, three, even four times as much ethanol as corn, and that can be
grown in sustainable, permaculture fashion -- plant once, never again,
no fertilizer or herbicides needed.
   Building smaller neighborhood or farm-scale ethanol plants as the
basis for permaculture operations is the way of the future. Digesters
making methane can and should be a part of that operation, especially
for the manure from the livestock you feed the spent mash to, and also
feed with the light stillage drained from the mash after distillation.


-- 
Harmon Seaver