Video: The Pros and Cons of Biomass
Here’s another part of our series for newcomers to the subject of renewable energy — this one on biomass. I provide a few thoughts on how it offers the potential to provide carbon-neutral renewable energy and biofuels.
[youtube http://www.youtube.com/watch?v=_ZdDZuAe6Qc]
Biomass conversion to energy based on intensive harvesting of feedstock from a given parcel of land is basically a mining operation. There is an ultimate depletion of the resource. This is obvious in the case of tires in a pile but fortunately more tires can be brought from elsewhere to keep the process going. The limitation is the energy required to transport the tires to repentish the supply that feeds the bioreactor.
The depletion is less obvious in the case of corn stover, switch grass, waste wood from logging and other intensive gathering processes from a land parcel. Micronutrients are depleted in the soil and soil physical characteristics are altered as humus levels decrease. This can be partially ameliorated by returning ashes from combustion to the land but this reaches a point of diminishing returns when hauling distances become prohibitive.
German experiences in the Black Forest for half of a millenium have borne out the depletion effect but they have learned to manage it with proper fertilization.
I do believe that there is sustainable long term viability for biomass conversion to energy but the process must be approached with eyes wide open and a careful analysis of past attempts. Larry Lemmert/ Wautoma, WI