Course: BFM 101 Biofuels Fundamentals

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Bioenergy Crop Production: a Crop-by-Crop Analysis
Conclusions

Crop Handling & Logistics
Crop Handling & Logistics

Harvest

Generally, biofuels can be grown and harvested with traditional farm and logging equipment. However, new developments in biofuel production may call for alternative or modified production or harvesting techniques. Examples of recent equipment innovations include in-field cob collectors that follow behind the combine and stalk-cutting attachments mounted on combine heads. Regardless, harvesting equipment will be unique to the crop type and production enterprise. Producers considering purchasing this equipment will need to evaluate the cost of new equipment versus the expected return from the investment. An alternative to this would be to hire a custom harvester, which would save the farmer the capital investment and maintenance costs.

Densification

One of the main barriers to building a successful biomass energy industry is that most raw biomass is not immediately useful as an energy source. Corn stover cannot be poured directly into a fuel tank, and switchgrass cannot be easily fed into a woodstove. Typically, biofuel crops must be compacted or densified, making them easier to handle and transport. Pelletizing, briquetting, and chipping are the most common densification methods used. Densification increases the weight per cubic foot, which reduces transportation and handling costs.

Storage

Many variables affect the storage of bioenergy crops. Things like the type and condition of feedstock and how it was harvested are important factors in how it should be stored. For example, grains should be kept at the proper moisture content and in an approved storage bin. Cellulosic feedstock crops such as native grasses and forbs are usually baled (round or large square) and stored in a stack in the field or near the farm site. Stacked bales should be covered or put in a covered storage area; they can also be individually wrapped with a waterproof cover. Woody bioenergy crops like poplar and willow are usually cut to length (8 to 10 feet, depending on facility specifications,) and hauled and piled near the field. They can then be stored as logs or chipped and hauled to the processing plant. Willow harvesters cut and bale or chip on-site. Woody bales and chip piles can maintain quality even if they are exposed to the weather. They can be stored in the field or in a covered storage area.

Storage policy and practices should be discussed with the biomass processer before contracts are finalized. Improperly stored feedstock can lose quality, which will decrease the price per ton the farmer receives for the crop.

Transportation

Biomass-based ethanol has less energy per unit (11,500 lbs/BTU) than gasoline (18,902 lbs/BTU). Therefore, transportation costs are higher for ethanol than for gasoline. Hauling low bulk-density, unconsolidated material is not economical. Densified biomass increases the weight per cubic foot and allows it to be transported more cost-effectively. Engineers are working to develop equipment that can harvest and densify biomass all in one pass. It will be some time before this technology will be available to farmers. Equipment will also be needed for transporting the densified biomass. Most farms are equipped to handle free flowing grain. This equipment is not designed to handle bales, chips or chopped material.

For more information, please consult the following references:

- Bioenergy Conversion Factors, Bioenergy Feedstock Development Program, Oak Ridge National Laboratory, http://bioenergy.ornl.gov/papers/misc/energy_conv.html. Accessed November 16, 2010.
- Fuel from Farms: A Guide to Small Scale Ethanol Production, US Department of Energy, Feb. 1980.

Resources provided by the eXtension Farm Energy Community of Practice at http://www.extension.org/ag+energy

Bioenergy Crop Production: a Crop-by-Crop Analysis
Conclusions