BIOMASS ABDULAZEEZ MUHAMMAD 118559 ITEC211
CONTENT • BIOMASS • WHERE DOES IT COME FROM ? • TYPES OF BENEFICIAL BIOMASS • METHODS OF CONVERSION • ADVANTAGES AND DISADVANTAGES
BIOMASS Biomass is plant material and animal wastes used to produce energy. It is the oldest form of renewable energy known to humans.
WHERE DOES IT COME FROM? Through the process of photosynthesis, plants combine carbon dioxide from the air and water from the ground to produce carbohydrates (sugars) and oxygen. Energy is released when the plant is burned. oxygen from the atmosphere combines with the carbon in plants to produce carbon dioxide and water. The process is cyclic.
TYPES OF BENEFICIAL BIOMASS • Energy crops • Crop residues • Manure • Urban wastes
TYPES OF BENEFICIAL BIOMASS • Energy CropsEnergy crops can be grown on farms in potentially large quantities and in ways that don’t displace or otherwise reduce food production, such as by growing them on marginal lands or pastures or as double crops that fit into rotations with food crops. Trees and grasses that are native to a region often require fewer synthetic inputs and pose less risk of disruption to agro-ecosystems
CROP RESIDUES • Depending on soils and slope, a certain fraction of crop residues should be left in the field to maintain cover against erosion and to recycle nutrients, but in most cases some fraction of crop residues can be collected for renewable energy in a sustainable manner. Food processing also produces many usable residues.
MANURE • Manure from livestock and poultry contains valuable nutrients and, with appropriate management, should be an integral part of soil fertility management.
Urban wastes • People generate biomass wastes in many forms, including "urban wood waste" (such as tree trimmings, shipping pallets and clean, untreated leftover construction wood), the clean, biodegradable portion of garbage (paper that wouldn’t be recycled, food, yard waste, etc.). In addition, methane can be captured from landfills or produced in the operation of sewage treatment plants and used for heat and power, reducing air pollution and emissions of global warming gases.
GASIFICATION • Gasification is a process that converts organic or fossil based carbonaceous materials into carbon monoxide, hydrogen and carbon dioxide. This is achieved by reacting the material at high temperatures (>700 °C), without combustion, with a controlled amount of oxygen and/or steam
PROCESSES OF GASIFICATION • Drying • Pyrolysis • Combustion • Reduction
PROCESSES OF GASIFICATION • DRYING. The biomass is exposed to heat in the gasifier and the water will boil out, leaving behind dry biomass. • PYROLYSIS. When heat is applied to biomass, the volatile compounds escape and are broken down to simple compounds due to the heat. This steps leaves behind charcoal, which is due to the very strong carbon-carbon bonds and the complex structure of the lignin molecule (lignin being the main protein that gives wood its strength • COMBUSTION. The complex tars and charcoal are then burned in the presence of oxygen and turn into water vapors and carbon dioxide. • REDUCTION. This step occurs almost simultaneously to cracking and combines carbon and oxygen atom to produce carbon monoxide (CO) and carbon dioxide. The same goes for hydrogen, which is converted back into water.
METHODS OF CONVERSION • THERMAL CONVERSION • BIOCHEMICAL CONVERSION • CHEMICAL CONVERSION
THERMAL CONVERSION • Thermal conversion processes use heat as the dominant mechanism to convert biomass into another chemical form.
CHEMICAL CONVERSION • A range of chemical processes may be used to convert biomass into other forms, such as to produce a fuel that is more conveniently used, transported or stored, or to exploit some property of the process itself.
BIOCHEMICAL • Biochemical conversion makes use of the enzymes of bacteria and other microorganisms to break down biomass. In most cases, microorganisms are used to perform the conversion process: anaerobic digestion, fermentation, and composting.
advantages • Utilizing biomass reduces • Dependence on expensive imported oil • Net greenhouse gas emissions • Toxic air emissions • Air pollution • Agricultural economy is also supported when biomass is utilized.
Advantages Biomass energy can reduce air pollution, provide important wildlife habitat, reduce soil erosion, and improve soil quality. Rural economies can become energy self-sufficient by using locally grown crops to generate electricity for their homes and fuels for their cars.
disadvantages • Biomass is expensive (in terms of producing and converting it to alcohols). • There is also difficulty in collecting and storaging large amounts of biomass for power generation. • If directly burned particulate matter pollution is a major concern • Possible toxic pollution from combustion of herbicides and pesticides on crop
disadvantages • Combustion of biomass products require some land where they can easily be burnt. • Consumes more fuel
references • http://www.ucsusa.org/clean_energy/our-energy-choices/renewable-energy/how-biomass-energy-works.html#Types_of_Biomass. • http://www.nrel.gov/biomass/ • http://www.conserve-energy-future.com/Advantages_Disadvantages_BiomassEnergy.php