Biomass
Biomass can be understood as regenerative (renewable) organic material that can be used to produce energy. These sources include aquatic or terrestrial vegetation, residues from forestry or agriculture, animal waste and municipal waste. If developed properly, biomass can and should supply increasing amounts of biopower.
Biomass is grown from several plants, including switch grass, hemp, corn, poplar, willow and sugarcane. The particular plant used is usually not very important to the end products, but it does affect the processing of the raw material. Though biomass is a renewable fuel, its use can still contribute to global warming. This happens when the natural carbon equilibrium is disturbed; for example by deforestation or urbanization of green sites.
Biomass is part of the carbon cycle. Carbon from the atmosphere is converted into biological matter by photosynthesis. On decay or combustion the carbon goes back into the atmosphere. This happens over a relatively short timescale and plant matter used as a fuel can be constantly replaced by planting for new growth. Therefore a reasonably stable level of atmospheric carbon results from its use as a fuel.
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[edit] Biomass and fossil fuel
Fossil fuels such as coal, oil and gas are also derived from biological material, however material that absorbed CO2 from the atmosphere many millions of years ago.
As fuels they offer high energy density, but making use of that energy involves burning the fuel, with the oxidation of the carbon to carbon dioxide and the hydrogen to water (vapour). Unless they are captured and stored, these combustion products are usually released to the atmosphere, returning carbon sequestered millions of years ago and thus contributing to increased atmospheric concentrations.
The vital difference between biomass and fossil fuels is one of time scale.
Biomass takes carbon out of the atmosphere while it is growing, and returns it as it is burned. If it is managed on a sustainable basis, biomass is harvested as part of a constantly replenished crop. This is either during woodland or arboricultural management or coppicing or as part of a continuous programme of replanting with the new growth taking up CO2 from the atmosphere at the same time as it is released by combustion of the previous harvest.
This maintains a closed carbon cycle with no net increase in atmospheric CO2 levels.
[edit] Biomass materials
- 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.
- 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
- 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.
- Municipal Solid Waste - Waste Paper, cardboard, wood waste and yard wastes are examples of biomass resources in municipal wastes.
- 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.
[edit] 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 fuel 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 fuel 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 Urban 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.
- Building materials
- Biodegradable plastics and paper (using cellulose fibres)
- Plastic from biomass, like some recently developed to dissolve in seawater, are made the same way as petroleum-based plastics, are actually cheaper to manufacture and meet or exceed most performance standards. But they lack the same Water resistance as conventional Plastics.
