Mubashshir Arif04 PKB 057BIOMASS
Biomass is matter usually thought of as garbage.
If garbage can be converted to useful energy?
How biomass works is very simple.
Recycling biomass for fuel and otheruses cuts down on the need for "landfills" hold garbage.
Biomass is biological material derived from living, or recently living organisms. In the context of biomass for energy this is often used to mean plant based material, but biomass can equally apply to both animal and vegetable derived material.What is the Biomass ?Chemical compositionBiomass comes in a million physical formsHowever, it is composed typically of Cellulose - 50%Hemi cellulose - 25%Lignin - 25%
Most biomass can be represented by
Plant materialThe carbon used to construct biomass is absorbed from the atmosphere as carbon dioxide (CO2) by plant life, using energy from the sun.These processes have happened for as long as there have been plants on Earth and is part of what is known as the carbon cycle.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 (vapor). 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.Fossil fuels
The difference between the biomass and fossil fuelThe 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 programmer 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.
HOW WAS BIOMASS USED IN THE PAST?
Biomass was the first fuel mankind learned to use for energy. Burning wood for warmth and cooking and keeping wild animals away Some of the earliest power plants in America were fueled by wood material It was an abundant fuel in many parts of the country where logging took place It burned much cleaner than coal and it was available before abundant oil and natural gas was discovered
Many cultures used animal dung to burn, and some are still doing this today
There are five basic categories of BIOMASS material:Virgin wood, from forestry, arboricultural activities or from wood processing Energy crops: high yield crops grown specifically for energy applications Agricultural residues: residues from agriculture harvesting or processing Food waste, from food and drink manufacture, preparation and processing, and post-consumer waste Industrial waste and co-products from manufacturing and industrial processes.
CONVERSION OF BIOMASS WASTE INTO USEABLE FUEL
Gasification Exposing a solid fuel to high temperatures and limited oxygen produces biogas. Pyrolysis Heating the biomass can produce pyrolysis oil and phenol oil leaving charcoal. Digestion Bacteria, in an oxygen-starved environment can produce methane. Fermentation
Bio-material that is used to manufacture Ethanol and Biodiesel by an anaerobic biological process in which sugars are converted to alcohol by the action of micro-organisms, usually yeast. Solid Fuel Combustion Direct combustion of solid matter.
Biomass to Biogas
Biogas is produced by exposing biomass to high temperatures and limited oxygen.
Biogas energy can serve as a feedstock for electricity generation or a building block for chemicals.
PYROLYSIS Heat is used to chemically convert biomass to bio-oil. Pyrolysis Oil, is easier to store and transport than solid biomass material and can be burned like petroleum to generate electricity.
Phenol Oil, a chemical used to make wood adhesives, molded plastics and foam insulation. Wood adhesives are used to glue together plywood and other composite wood products.
DIGESTION Decomposition of organic matter by anaerobic bacteria in an oxygen-starved environment.
Heating Plant, Lior International
Dranco plant for anaerobic digestion of biowaste Ghent( Belgium )
Anaerobic digesters compost (or "digest") organic waste in a machine that limits access to oxygen encouraging the generation of methane and carbon dioxide by microbes in the waste. This digester gas is then burned as fuel to make electricity.
Lemvig centralised biogas plant, Denmark, producing about 4 million m3/year of gas
SOLID FUEL COMBUSTION
Direct combustion of solid matter where the biomass is fed into a furnace where it is burned. The heat is used to boil water and the energy in the steam is used to turn turbines and generators.
Eagar Biomass Plant, Springerville, Arizona
Peat is an accumulation of partially decayed vegetable matter. Peat forms in wetlands, bogs, moors, mires and fens
PURE PYROLYSISPure pyrolysis can be represented as...CH1.4O0.6 0.4 C (charcoal) + C.6H1.4O.6 (pyrolysis oil and gas)This requires an external heat source like the Bunsen flameTheres a better way to make gas...
THE SIMPLE MATCH: Flaming CombustionPyrolysis, gasification and combustion are all visible in the simple match. Please look CLOSELY
PROCESSES IN THE MATCH
FLAMING COMBUSTIONIf you have lots of air passing over a small amount of wood, it will burn completely to CO2 and H2O in flaming combustion, as in the match CH1.4O0.6 + 1.05 (O2 + 3.76N2)CO2 + .7H2O
If you have insufficient air passing through a mass of burning wood, you have flaming pyrolysis producing CO and H2, the basis of biomass gasification
THE KEYS TO BIOMASS THEMAL CONVERSIONPGC PYROLYSISGASIFICATIONCOMBUSTION
GASIFICATION FUEL RATIOIt is necessary to have the correct air (or O2)/fuel ratio to achieve complete gasification
With lower values of this ratio you have an excess of charcoal and tar
With higher values you deplete charcoal and burn product gas
We call the optimum ratio the Sweet Spot of gasification
Controlling the Sweet SpotThe correct air/fuel ratio depends on many things:Moisture contentType of biomassAir throughput rateSweet Spot control is the key to simple, clean gasification
LIMITATIONSGreenhouse gases produced by burning Extra costs of installing technology to process and recycle wastes Expensive to collect, harvest and store raw materials Large scale crop production will use vast areas of land and water, representing major problems
Biomass is very abundant. It can be found on every square meter of the earth as seaweed, trees or dung.
It is easy to convert to a high energy portable fuel such as alcohol or gas.
It is very low in sulphur reducing the production of acid rain.
Preservation of agricultural land that otherwise would be sold for residential development or industrial use = wide open spaces!!.
ADVANTAGES CONTDBiomass production can often mean the restoration of waste land (e.g. deforested areas).
It may also use areas of unused agricultural land and provide jobs in rural communities.
Sustainable agricultural techniques for these crops can restore and ensure soil stability and health along with minimizing chemical residues and habitat destruction
ContdToday 10,000 megawatts (MW) in total biopower capacity installed nationwide.Use of waste from agricultural and timber industries. An estimated 350 million tons of waste that goes to landfills could be used for energy production.Methane is 20 times more potent than CO2. Capturing methane from producers such as cows or rice fields and applying it for fuel will significantly reduce this greenhouse gas.
If it is produced on a renewable basis using biomass energy does not result in a net carbon dioxide increase as plants absorb it when they grow.
Biomass (Future) Advantages? Biomass can be used to produce solid, liquid, gaseous fuels as well as electricity directly Fuel production technology is (largely) mature Combustion/conversion technology is immature Plants store energy at the rate of ~ 3000 EJ/yr, 2/3 on land Humans already manage around 1/2 of the usable land area for food and fibre, and managed forests store ~ 600 EJ/yr.
Exa - 1018; Peta - 1015; Tera - 1012; Giga - 109; Mega - 1061 TW = 31.54 EJ/year
ConclusionsToday there are opportunities to convert biomass resources into liquid fuels, gaseous fuels and electricity to cater to developmental needs of rural areas Bioenergy produced locally can substitute fossil fuels and reduce import burden and create employment in rural area
it requires coordinated efforts of scientists, and engineers to overcome these limitations in order to translate this high potential technology to high performing technology