Ramble On

Monday, February 8, 2010

Clarification #2: Some Points on Biomass Energy Sources

This is a second clarifying post from Fibrowatt's Terry Walmsley, adding to the discussion from some of the posts last week. Pretty informative - thanks again for posting, Terry.


You mention the comparison with woody biomass. Often, poultry litter is drier than the woody biomass that is used for large-scale energy generation (as opposed to firewood or sawdust & shavings). Wood chips for use in power plants often come from green wood from forestry operations. So actually, based on moisture alone, less litter would be needed. On the other hand, poultry litter has a lot of dirt/nutrient content from the feed ration and the barn floor. As a result, a Fibrowatt plant may require more litter fuel than wood fuel based on the inert content as opposed to moisture content.

It should be understood that we also use woody biomass as a supplemental fuel as it covers periods when litter deliveries are lower and makes it easier to manage the litter when these are mixed together for storage and conveying to the boiler.

With regard to the transportation, we try to maximize the litter payload and this material is far more dense than wood. We try to reach a maximum payload when transporting litter, well above 14 - 20 ton loads you mention. Furthermore, the transportation side of our business is a point of emphasis as we must meet important poultry industry requirements for our transportation. As a result, we are very involved in the requirements of truck type and enclosed payloads. If you look at our operation in Minnesota, we have tightly covered loads as a basic requirement and these truck tarps are inspected when they arrive at the plant. Tight trucks mean no loss of fuel and no odor problems.

With regard to poultry litter storage. You are right that poultry litter smells, that is why all litter is stored inside a fully enclosed fuel hall. To control odor, we establish what is defined as "negative pressure" to ensure that air flows into the fuel hall, but not out. This is done by drawing our combustion air from within the fuel hall, and thereby destroying these odors in the combustion process. All trucks are unloaded within the fuel hall. Stand outside of a truck delivery door and you can feel the air flowing into the building. Best evidence of the success of negative pressure is that after 2.5 years of operation we have not had an odor complaint. The size of the storage area is far less than you mention because we stack the litter in large piles within the enclosed fuel hall using cranes to move it from delivery, storage, and processing prior to conveying to the boiler building in a fully enclosed conveying system.

Terry Walmsley
Fibrowatt LLC

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