A New Technology to Turn Biomass
Waste Materials into an Upgraded Fuelp
Biomass waste materials, such as agriculture residues, wood processing
residues, waste paper and yard waste, are valuable green power resources. While
carbon dioxide is emitted during biomass combustion, an equal amount of carbon
dioxide is absorbed from the atmosphere during the biomass growth phase.
Therefore, use of biomass does not cause global warming. Besides, biomass
contains virtually no sulfur, so it emits no sulfur dioxide which is a
precursor of acid rain. The use of biomass as energy resource is highly
encouraged by the U.S. government.
Biomass waste materials are usually loose and unsuitable for direct use as
fuel. It must first be densified. The densified biomass is easy to handle,
store, transport, and burn in stove or power plants. However, the high cost of
conventional means of densification – pelletizing – prohibits the widespread
use of biomass as fuel. The current market price for biomass pellets, which are
mainly made of wood residues and used as fuel in domestic pellet stoves, is
about $150 per ton!
During the period 1998-2001, Dr. Henry Liu and his colleagues at University of
Missouri- Columbia received grants from the U.S. Department of Energy (DOE),
and Missouri Department of Natural Resources (MDNR), to study compaction of
biomass materials. They succeeded in developing a high-pressure compaction
technology to turn waste materials into dense compacts of cylindrical shapes
called “logs.” Various types of biomass materials, including wood processing
residues, yard waste, switchgrass, waste paper, and many others, were tested
and found able to be compacted into high-quality fuel logs with a density of
1.1 g/cm3 approximately. These densified biomass logs are ideal fuels for
household stoves, for co-firing with coal at power plant, and for gasification
plants. An economic analysis conducted under DOE sponsorship indicates that the
cost for mass production of 5.4-inch-diameter biomass logs is in the range of
$5 to $8 per ton. Smaller logs of 1.9-inch diameter cost in the range of $8 to
$14 per ton. These cost figures include not only costs and taxes, but also a
15% above-inflation return on investment. They don’t include the cost of
planting biomass (if not using waste materials such as yard waste), collection
and transportation. Production of biomass logs also uses less energy than
producing biomass pellets. The biomass log is a superior solid fuel and less
costly than biomass pellets. Photos below show biomass logs made of cut grass
and waste paper.
