Biomass Research
The Forest Operations Unit of the Southern Research Station (SRS) has been involved in biomass-related research since the late 1970's. Biomass is a source for biofuels as an alternative to gasoline and other oil-based products. High energy demands have created a need to further develop economically viable ways to harvest this renewable resource. Therefore, our studies in this area continue.
Our Research Unit has nine primary research topic areas related to biomass: biomass harvesting systems; economic analysis; bundling; individual machines; proto-type machines; energywood chipping systems; environmental considerations; short rotation woody crop production; and drying, storing, transporting & roll splitting.
For more information on mechanical fuel reduction treatments visit our mastication webpage.
Current Studies
- Equipment Reviews
- Production and Cost Studies
Recent Outputs
 Forest Residues Bundling Project CD
During the summer of 2003, the USDA Forest Service conducted an evaluation of biomass bundling for forest residue extraction. This CD provides a report of the project results, a video documentary project record, and a collection of images from the project. To obtain a copy of the CD just complete and submit the order form below and one will promptly be mailed to you. Additional information is available at: http://www.fs.fed.us/forestmanagement/WoodyBiomassUtilization/
Bundler Project CD Order Form
Biomass Publications from the Forest Operations Research Unit: A Synthesis
Our unit has been studying biomass-related topics since 1977. This CD aids the reader by organizing these publications in one easy-to-use CD. Included on the CD are an executive summary, two bibliographies, individual publications (in PDF format), and a keyword listing. The types of publications on the CD consist of presentation reports, published reports, portions of books, and master's theses.
The CD can be accessed by visiting: http://www.srs.fs.usda.gov/pubs/biomass_cd
To obtain a copy of the CD simply complete and submit the order form below and one will promptly be mailed to you, or contact Dana Mitchell, Research Engineer, at 334-826-8700 or danamitchell@fs.fed.us.
Biomass Publications CD Order Form
Forest Residue Trucking Simulator (version 5)
The Forest Residues Transportation Model (FoRTS) is a spreadsheet calculator designed to help you compare alternative methods of moving biomass from the forest to a wood-using facility. It will let you:
1) estimate loading and hauling costs for different combinations of equipment
2) evaluate the best mix (numbers and types) of equipment
3) compare different hauling routes
4) examine reloading, or two-stage hauling opportunities
You can use default values for basic comparisons or input your own numbers to examine specific projects.
The model will NOT give actual costs for these operations because it does not include factors such as profit and overhead. It is intended to represent a relative comparison among options.
To learn more about the program or to obtain a copy of the spreadsheet, simply download the following files.
FoRTS Overview (1.5 Mb pdf file)
FoRTS v5 (1.7 Mb Excel file)
Biomass Moisture Content
The moisture content of biomass affects the gross weight of the material that is being handled. Green material will have a higher density than drier material because of the extra water weight in the cells of the wood. In biomass markets, it is important for all parties to have a common understanding of the dry mass of material that is being sold or processed. Generally biomass loads are sampled for moisture content and then converted to a dry-basis measure such as "bone dry tons" or "bone dry units."
A bone dry ton (bdt) is an amount of material that weighs 2000 lbs when it is dry. A bone dry unit (bdu) is an amount of material that weighs 2400 lbs when it is dry. Bone dry tons are used in some biomass markets, particularly where logs are being processed. Bone dry units are found in other markets, particularly where the predominant form is chips or hog fuel. Another term used in some residue transactions is the "unit" or "gravity packed unit (GPU)." A GPU is the amount of material in a volume of 200 cubic feet. This volume measure should not be confused with the "cunit" or a measure that is 100 cubic feet of solid wood. For a full description of wood measurements and conversions, see Forest Products Measurements and Conversion Factors by David Briggs (www.ruraltech.org/projects/).
Moisture content measurement can be done in several ways. Electronic moisture meters can measure moisture content indirectly. More exact measurement requires actually drying a sample of material and determining the dry weight and the weight of water that was originally in the sample. The calculation of moisture content can be done in one of two ways:
%MCod = wt. of water / wt. of wood * 100 (This is MC oven-dry basis)
or
%MCwb = wt. of water / (wt. of wood + wt. of water)*100 (This is MC wet basis)
You can convert %MCod to %MCwb using the formula:
%MCwb = %MCod*100 / (100 + %MCod).
To go the other way us the formula:
%MCod = %MCwb*100 / (100 - %MCwb)
To have this calculation done for you and see this illustrated graphically, you can download the Moisture Content Converter (Excel file).
Biomass and Heat Value
A very useful parameter to know when dealing with biomass is the heat value, or heat of combustion, which is defined as the total amount of heat obtainable from ovendry material when burned in an enclosure of constant volume, allowing no deductions for heat losses (Koch, P. 1985. Utilization of hardwoods growing on southern pine sites. U.S. Dep. Agric. For. Serv., Agric. Handb. 605 3710 p. 3 vol.). Since biomass is mainly used as a fuel source, it is helpful to know the fuel potential of the material being used. A number of variables affect heat value, the most important being moisture content, species, and the portion of the tree being used (stemwood, branchwood, bark). Heat value is normally expressed in Btu's/ovendry pound. A Btu is defined as the heat required to raise the temperature of 1 lb of water from 63 deg F to 64 deg F (Serway, R.A., 1983. Physics for scientists and engineers with modern physics, 2nd edition, p. 427. Saunders College Publishing). Heat values for some common hardwoods are listed in Table 1.
Table 1. Heat of combustion (Btu/ovendry pound) of stems and branches of 6-inch trees of 22 hardwood species growing on southern pine sites (Data from Manwiller).
| Species |
Stem-wood
|
Stem-bark |
Branch-wood |
Branch-bark
|
| Ash, green |
7,695 |
7,472 |
7,727 |
7,606 |
| Ash, white |
8,033 |
7,695 |
8,013 |
7,816 |
| Elm, American |
7,770 |
6,840 |
7,857 |
6,904 |
| Elm, winged |
7,917 |
7,019 |
7,869 |
6,889 |
| Hackberry |
7,882 |
7,147 |
7,867 |
7,141 |
| Hickory, sp |
8,183 |
7,586 |
7,931 |
7,259 |
| Maple, red |
7,846 |
7,595 |
7,829 |
7,384 |
| Oak, black |
7,680 |
7,642 |
7,692 |
7,847 |
| Oak, blackjack |
7,739 |
7,766 |
7,739 |
7,907 |
| Oak, cherrybark |
7,848 |
7,582 |
7,737 |
7,655 |
| Oak, laurel |
7,828 |
7,897 |
7,653 |
7,806 |
| Oak, northern red |
7,791 |
7,879 |
7,776 |
7,926 |
| Oak, post |
7,889 |
7,191 |
7,845 |
7,728 |
| Oak, scarlet |
7,798 |
8,041 |
7,673 |
7,894 |
| Oak, Shumard |
7,789 |
7,970 |
7,745 |
7,913 |
| Oak, southern red |
7,919 |
7,983 |
7,839 |
7,798 |
| Oak, water |
7,876 |
7,930 |
7,833 |
7,918 |
| Oak, white |
7,676 |
7,328 |
7,507 |
7,574 |
| Sweetbay |
7,736 |
7,822 |
7,802 |
7,886 |
| Sweetgum |
7,667 |
7,200 |
7,690 |
7,214 |
| Tupelo, black |
7,867 |
7,788 |
7,814 |
8,176 |
| Yellow-poplar |
7,774 |
7,696 |
7,811 |
7,666 |
Average |
7,827 |
7,593 |
7,784 |
7,632 |
Heat values for some materials derived from southern pine trees are shown in Table 2.
Table 2. Heat of combustion (Btu/ovendry pound) of various materials from southern pine trees (data from Howard).
| Material |
Average |
Range |
| Resin |
|
14,625 to 16,250 |
| Charcoal |
12,335 |
11,225 to 12,740 |
| Needles |
9,030 |
8,935 to 9,105 |
| Loblolly pine stemwood |
8,600 |
8,310 to 9,352 |
| Earlywood |
8,610 |
8,470 to 8,760 |
| Latewood |
8,585 |
8,385 to 8,755 |
| Rootwood |
8,605 |
8,560 to 8,680 |
| Tops (bark & wood at 1" top) |
8,395 |
8,015 to 8,745 |
| Old cones |
8,130 |
8,085 to 8,190 |
| Kraft black liquor |
5,965 |
5,820 to 6,130 |
Options for Transporting Biomass
Options for Transporting Biomass (3.7Mb pdf file)
Presentations (.pdf format only)
Links
Southern Alliance for the Utilization of Biomass Resources
US Department of Energy, Energy Efficiency and Renewable Energy
Fuels for Schools
National Renewable Energy Laboratory
USDA Forest Service, Forest Management Service Center
Louisiana Forestry Association
American Bioenergy Association
US Department of Energy, Energy Information Agency
Short Rotation Woody Crops Operations Working Group
Southeastern Regional Biomass Energy Program
Woody Biomass Utilization - About Us
Woody Biomass Utilization - Markets Publications & Other Information
Memorandum of Understanding (MOU)
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