lecture10,11

7/28/2019 lecture10,11

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BIOMASS TO

ENERGY

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What is meant by Biomass

• Materials produced by metabolic activities of biologicalsystems (plants and animals) and/or products of their

decomposition or conversion

• The materials are based on carbon compounds

• The chemical and energetic value of those materials isbased on the carbon-carbon and carbon-hydrogen bond

• Biomass suitable for utilization must have a net heating

value

• Biomass is infact collected and stored solar energy

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Sources of Biomass

• agriculture

• residues from forestry, specific industries (e.g. furniture

production, saw dust), food processing

• solid municipal and industrial wastes

• used wood e.g. from old furniture, used timber

• marine systems: the oceans of our world contain much

more biomass than existing on the continents (but they are

not regarded as a source of biomass for energetic

utilization)

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• Bio Mass from cattle manure, agricultural waste,

forest residue and municipal waste.

• Anaerobic digestion of livestock wastes to give bio

gas• Fertilizers as by product.

• Average electricity generation of 5.5kWh per cow

per day!!

Sources of Biomass

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Carbon Neutral

• Energy is produced from biomass by basically burningorganic matter to release its stored chemical energy that it

has accumulated through the process of photosynthesis.

Using biomass contributes very little to the build-up of

greenhouse gases. Although plants will release their storedcarbon dioxide (CO2) when burned, that CO2 is recaptured

and used by other plants as they grow. Therefore,

theoretically there is no net gain of carbon dioxide because

of a cycle of usage

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Bio Mass: contribution in Energy

• Biomass already supplies 14 % of the world’sprimary energy consumption. On average, biomassproduces 38 % of the primary energy in developingcountries.

• USA: 4% of total energy from bio mass, around9000 MW

• INDIA is short of 15,000 MW of energy and it costsabout 25,000 crores annually for the government toimport oil.

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Biomass Utilization & Conversion

• Densification

• Microbial treatment• Thermal treatment

• Chemical treatment

• Mechanical processes

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DensificationBIOMASS DENSIFICATION is the process of compacting low a

bulk density material into a product of high density Densification

has stimulate a great deal of interest worldwide in recent years asa technique of beneficiation of residues for utilization as energy

source. Densified biomass is mostly in the form of briquettes in

developing counties and in the form of pellets in developed

countries.• BriquettesBriquetting is the process of densification of biomass to produce

homogeneous, uniformly sized solid pieces of high bulk density

which can be conveniently used as a fuel.

• PelletsPelletizing is closely related to briquetting except that it uses

smaller dies (approximately 30 mm) so that the smaller products

are called pellets.

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Briquettes• Piston Press

In the die and punch technology, which is also known as ram anddie technology, biomass is punched into a die by a reciprocating

ram with a very high pressure thereby compressing the mass to

obtain a compacted product. The standard size of the briquette

produced using this machine is 60 mm, diameter. The power required by a machine of capacity 700 kg/hr is 25 kW. The ram

moves approximately 270 times per minute in this process.

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Piston Press

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BriquettesScrew Press

In this process, the biomass is extruded continuously by oneor more screws through a taper die which is heated externally

to reduce the friction. Here also, due to the application of high

pressures, the temperature rises fluidizing the lignin present

in the biomass which acts as a binder. The outer surface of the briquettes obtained through this process is carbonized

and has a hole in the centre which promotes better

combustion. Standard size of the briquette is 60 mm

diameter.

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Screw Press

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Pellets

• Flat/disk Type• The flat die type features a circular perforated disk on which

two or more rollers rotate. The ring die press features a

rotating perforated ring on which rollers press onto the inner

perimeter. Large capacity pelletizers are available in therange of 200 kg/h to 30 ton/h thus pellets press capacity is

not restricted by density of the raw material as in the case

of piston or screw presses. Power consumption falls within

the range of 15 – 40 kWh/ton.

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Flat/disk Type

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Microbial Treatment

• Long traditions in many cultures in the field of foodprocessing e.g. beer brewing, alcoholicfermentation, preservation technologies as lacticacid fermentation

• Waste treatment in agriculture and food industry byaerobic treatment (composting) and anaerobicfermentation

• Treatment of municipal and industrial waste water

• (Pre)Treatment of solid waste containing organicmaterials

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Aerobic Processes

Agricutural wastes:

Traditional method:composting

Treatment of solid

urban waste:Technology withgood prospects

Pretreatment of hazardous waste

Treatment of gaseous phases forde-odorizing

(e.g. compostfilters in fishindustry)

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Biomass contributions to energy supply :

electrical energy

• Wood, other biomass (Combustion, Pyrolysis)• Biogas

• Waste, sewage sludge (incineration, Fermentation)

• Chemical Processes: hydrogenation,transesterification

• BTL (Biomass to liquid)

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Wood Incineration units

• Normally chopped wood or chopped woody

residues are used as feeding materials for large

cogeneration plants

• For the heating of households pelletisedmaterials are available. By using them the

incineration process can be operated

automatically. The cost for the pelletized wood in

relation to mineral oil come to about 2/3

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19.5 MW – Plant for gerating heat and

electricity in Germany

• Input „fresh“ and old wood chops, 5.33 t/h max

• Steam production: 25.5 t/h

• Operation 8000 hours per year

• Energy output electrical from 3.8 to 5.1 MWdepending on heat delivery for the households

• Energy output thermal: maximum 10 MW

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Wood – a big potential of the forests

• In Germany there are growing about 60 millions

of m3 wood per year, that can be harvested

• Thats is an energtic equivalent of about 1.5TWh/a

• Compared to the actual energy consumtion of

Germany this is a potential of 50%

• Actual energetic utilization of wood comes to

0.09 TWh/a

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Wood burning in stoves

• Domestic heating with wood is still by farthe largest market for bio-energy

• Dramatic improvements of technology in

domestic heating equipment• Improved tiled stoves, advanced logwood

boilers, woodchip boilers, pellet boilers and

pellet stoves.• Pourable wood-based fuel is also available

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Tiled stoves

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Pellet Boilers and Stoves

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Logwood boiler

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Woodchip boilers

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Energy content of wood based substrates

average data

water content calorific value oil equivalent

(%) (kWh/kg ) L oil/m3

Pieces 20 4 165

Pellets 10 5 325

Chops 20 4 100Saw dust 40 2.6 70

-----------------------------------------------------------------------------------------------

Wheat 15 4 400 L/1000 kg

Pyrolysis

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Pyrolysis

Heating in the absence of air.

Pyrolysis of biomass generates three different energyproducts in different quantities: coke, gas and oils.

Conversion of solid fuels into combustible gas mixture

(CO + H2 + CH4)

TYPES

• Fluidized-bed fast pyrolysis

• Microwave-assisted pyrolysis

• Slow pyrolysis

• Intermediate pyrolysis

P l i Ad t

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Pyrolysis: AdvantagesIt can achieve significantly higher electrical efficiencies (22 % to37 %) compared to biomass combustion technologies with steamgeneration and standard turbine technology (15 % to 18 %).

The improved electrical efficiency of the energy conversion viapyrolysis naturally means that the potential reduction in CO2 isgreater than with combustion. The formation of NOx compoundscan also be greatly reduced and the removal of pollutants isgenerally in most cases.

For power plants with integrated biomass gasification in the range3 to 20 MW electricity, fluidized bed gasification of biomass under atmospheric pressure, coupled with gas turbines using the Chengcycle or gas and steam turbines appear to be the most promisingtechnology at present in technical and economic terms. For combined heat and power stations with capacities up to about 2MW electricity, gas use in gas-fired engines is, at the moment,more attractive than gas turbines.

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What is a Biogas Plant• Basically Methane & CO2 Gas Producer.

• Methane – Odorless, Colorless, Good Calorific

Value, Green House Gas

• Sources : Animal Manures, excreta, kitchenwaste, Industrial Chemical Processes, Sea

Water Bed, etc.

• Animal Manure & Excreta contributes around 16% of the total global methane emission.

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Schematic of a typical Biogas

Plant

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Anaerobic Digestion: Biogas Production process

MAIN STEPS• Collection and (pre)treatment

• Producing a slurry with balanced composition (e.g. water-content, total organic solids. C/N ratio)

• Feeding of reactor with constant rate

• Keeping fermenter at nearly constant temperature of about33o Centigrade

• Mixing of substrate during fermentation

• Gas collection, purification, utilization (heat and electricity)

• Collection and utilization of fermented slurry e.g as highvalue organic fertilizerer

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Applications

Power Generation Thermal Applications

o Irrigation Pumping

o Village Electrification

o Captive Power (Industries)

o Grid-fed Power from EnergyPlantations on Wastelands

o Simultaneous Charcoal and

Power Production

o Hot Air Generators

o Dryers

o Boilers

o Thermic Fluid Heaters

o Ovens

o Furnaces & Kilns

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Biogas Plants

Fermentaion

Gas and slurryutilization

Collection

andpretreatment

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Anaerobic Digestion of Sewage Sludge

Sewage sludge is fermented and used to

cover the energy demand of the waste water

treatment plants. By doing this those plantsneed no external energy. The biogas is used

for cogeneration of heat for the digesters an

electricity for the aerobic waste water

purification process (energy for pumping and

aeration of the waste water).

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Waste Incinration: Composting

Composting is a traditional technology in agricultureand gardening. Today there are processes of treatment of municipal waste which make use of theheat of composting for drying the solid waste before

separation under investigation. There is nosignificant contribution to the enegy supply of Germany by composting of biomass.Composting of mixtures of municipal and organicwaste of food industry is implemented in many cities

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Technology

• Biomass technology today serves many marketsthat were developed with fossil fuels and modestlyreduces their use

• Uses - Industrial process heat and steam, Electricalpower generation, Transportation fuels (ethanoland biodiesel) and other products.

• Primary focus of the Biomass Program – development of advanced technologies.

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Bio-refinery

• A facility that integrates biomass conversionprocesses and equipment to produce fuels,power, and chemicals from biomass.

• Analogous to today's petroleum refineries

• It is based on the “Sugar Platform“ and the“Thermochemical Platform“

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Modified Waste Vegetable Fat

• Designed for general use in most compressionignition engines .

• The production of MWVF can be achieved in acontinuous flow additive process.

• It can be modified in various ways to make a'greener' form of fuel

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Environmental Concerns

• Air Pollution

• Soil Deterioration

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Air Concerns

• Biomass processing technologies have the potential to

increase emissions of ozone precursors

o Increase in Nox emissions

•Emission of relatively large sized particulate matter

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Soil Concerns

• Burning biomass deprives local eco-systems of nutrients

•

Production of dedicated energy crops renders land fallow

• Reduced land availability for cattle grazing

•Increased use of pesticides and fertilizers to produce energy

crops contaminate ground and surface water

o Affects fish and wildlife

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Environmental Benefits

•Reduction of waste

•

Extremely low emission of greenhouse gases compared tofossil fuels

•Carbon neutral and forms a part of the carbon cycle

• Growing variety of crops increases bio-diversity

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Future

The future development will be based onincreasing production of energy crops, optimized

utilization of organic residues and on thermal-

chemical treatment of organic matter to produce

gaseous and liquid fuels.

There are lot of estimations for future contributions

of biomass to energy supply, they will come to at

least 20 or 30 percent until 2020.

lecture10,11

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