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Understanding Biomass
Last Updated:
11/30/2010 11:12:25 AM |
| Biomass as an energy source
is is material derived from recently living organisms - i.e. plants and to
a lesser extent animal materials. This non-fossil energy can be used to
supply heat, electricity and transportation fuels. It is a renewable
alternative to coal, oil and natural gas. |
| Biomass includes all land and
water-based vegetation such as dedicated energy crops and trees, agricultural
food and feed crops, agricultural crop wastes and residues, wood wastes and
residues, aquatic plants, animal wastes, municipal wastes, and other waste
materials. |
| Biomass is the product, either
directly or indirectly, of photosynthesis — the process by which plants use
solar energy and atmospheric carbon dioxide to make carbohydrates including
sugars, starches and cellulose. |
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Energy crops are
fast-growing plants, trees or other herbaceous biomass which are harvested
specifically for energy production use. These crops can be grown, cut and
replaced quickly.
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Herbaceous Energy Crops --
These include grasses such as switchgrass, miscanthus (Elephant grass),
bamboo, sweet sorghum, tall fescue, kochia, wheatgrass, and others. These
crops are generally grown for fuel production. These energy crops
are perennials. Perennials generally take two to three years to
reach full productivity.
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Biomass is grown from
several plants, including
miscanthus,
switchgrass, hemp, corn, and
trees.
Industrial Crops --
Industrial crops are being developed and grown to produce specific
industrial chemicals or materials. Examples include kenaf and straws for
fiber, and castor for ricinoleic acid.
Agricultural Crops -- These
feedstocks include the currently available commodity products such as
cornstarch and corn oil; soybean oil and meal; wheat starch, other
vegetable oils, and any newly developed component of future commodity
crops.
Aquatic Crops -- A wide
variety of aquatic biomass resources exist such as
algae, giant kelp, other seaweed, and marine microflora.
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Biomass Processing Residues.
All processing of biomass yields byproducts and waste streams collectively
called residues, which have significant energy potential. Not all residues can
be used for electricity generation, some must be used to replenish the source
with nutrients or elements. Still, residues are simple to use because they
have already been collected.
• Pulp and paper operation residues. These
residues are the byproducts of logging and processing operations such as
sawdust, bark, branches and leaves/needles. In general, paper mills
use their pulp residue to create energy for the paper mill.
• Forest residues. Forest residues
include wood from forest thinning operations, materials not harvested or
removed from logging sites in commercial hardwood and softwood stands and
dead/dying trees.
• Agricultural or Crop Residues. These
residues are the leftovers of crop harvesting. Agriculture crop residues
include corn stalks and leaves, wheat straw, rice straw and nut hulls, to
name a few.
- Animal waste, such as cattle, chicken
and pig manure, can be converted to gas or burned directly for heat and
power generation. These wastes can be used to make many products and
generate electricity through methane recovery methods and
anaerobic digestion
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Urban wood waste. Urban wood
waste generally consists of lawn and tree trimmings, whole tree trunks,
wood pallets and any other construction and demolition wastes made from
lumber. This rejected material can easily be collected after a
construction or demolition project and turned into mulch, or compost.
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Municipal Solid Waste. Waste
paper, cardboard, wood waste and yard wastes are examples of biomass
resources in municipal wastes.
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Landfill gas. The natural
byproduct of bacterial digestion of organic garbage contains vast amounts
of methane which can be captured, converted and used to create energy.
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Consider the benefits of
biomass energy:
- A biomass fuel based
power plant converts an existing waste stream to useful electrical energy.
- A biomass fuel based
power plant uses a completely renewable fuel. Craven's energy output
displaces generation from non-renewable fossil fuels that have limited
reserves and are being rapidly depleted.
- A biomass fuel based
power plant provides a completely domestic energy supply, reducing our
dependence on foreign oil. Craven's annual production of 350,000 MWH
is the equivalent of approximately one half million barrels of foreign oil.
- A biomass fuel based
power plant utilizes a local fuel source, resulting in a boost to the local
economy. Fossil fuels are not indigenous to North Carolina and result
in a drain on the state's economy.
- A biomass fuel based
power plant is completely dispatchable, i.e. output can be varied and
matched with customer demand. Unlike other sources of renewable energy
that are instantaneously dependent on natural forces.
- A biomass fuel based
power plant diverts material from landfills, prolonging the life of these
landfills. North Carolina is rapidly running out of landfill capacity,
and much of the material being land filled is wood waste.
- A biomass fuel based
power plant has extremely low air emissions.
- Sulfur dioxide emissions are
insignificant since there is virtually no sulfur in wood. Due to the
moisture content, biomass combust at a cooler temperature than fossil
fuels, resulting in inherently lower nitrous oxide emissions.
Although all combustion processes release carbon dioxide, biomass
combustion has a neutral "carbon balance," since trees convert carbon
dioxide to oxygen. In addition, decomposing wood emits carbon
dioxide, as well as methane – a greenhouse gas 22 times worse than carbon
dioxide.
- A biomass fuel based
power plant can recycle the fly ash produced. At CCWE, it is recycled
as an agricultural liming agent, providing a benefit to local farmers.
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